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MICROCOPY RESOLUTION TEST CHART MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF STANOAROS-1963-A NATIONAL BUREAU Of STANDAROS-1963-A
t)~ t-~ bull ~ Itmiddot
A Revision of the Genus Sennius of North and Central America
(ColeoF~ra Bruchidae)
Technic(l Bulletin No 1462
Agricultural Research Service UNITED STATES DEPARlMENT OF AGRICULTURE
in cooperation with Northern Arizona University
j
A Revision of the Genus Sennius of North and Central America
(Coleoptera Bruchidae)
Technical Bulletin No 1462
Agricultural Research Service UNITED STATES DEPARTMENT OF AGRICULTURE
in cooperation with Northern Arizona University
Washington DC Issued ]darch 1973
For sale by the Superintendent of Documents US Government Printing Office Washington DC - Price $175 domestic postpaid or $150 GPO Bookstore
Stock Number 6166-62656
~
ACKNOWLEDGMENTS
We thank the following persons for the generous loan of specishymens for this study R H Arnett Purdue University W F Barr University of Idaho D E Bright Canadian National Collection of Insects Ottawa H R Burke Texas A amp 11 University G W Byers University of Kansas O L Cartwright Smithsoniari Inshystitution Washington DC J B Chapin Louisiana State Univershysity J A Chemsak University of California Berkeley P J Clausen University of Minnesota H Dybas Field Museum of Natural History Chicago M Emsley Academy of Natural Scishyences Philadelphia S Frommer University of California Rivershyside F F Hasbrouck Arizona State University K L Hays Auburn University M T James Washington State University J D Lattin Oregon State University R J Lavigne University of Wyoming J F Lawrence Museum of Comparative Zoology Harvard University H B Leech California Academy of Sciences G H Nelson Kansas City College of Osteopathy and Surgery L L Pechuman Cornell University P C Peterson University of Nebraska E P Rouse University of Arkansas R R Snelling Los Angeles County Museum R T Thompson British Museum (Natural History) P H Timberlake University of California Riverside C A Triplehorn Ohio State University J D Unzicker Illinois State Natural History Survey G E Wallace Carnegie Museum Pittsburgh R L Wenzel Field Museum of Natural History Chicago F G Werner University of Arizona and D A Young North Carolina State University
For identifying the many plants collected during this study we thank R H Hevly and J M Rominger Northern Arizona Unishyversity and W H Lewis Missouri Botanical Garden
The figures were draWll by Miss Deborah Learned and Rosser Garrisoll Northern Arizona University and the junior author
Rodolpho Hernandez Corzo Director General Direccion General de la Fauna Silvestre Mexico DF was especially cooperative in procuring permits for collecting in Mexico His help is gratefully acknowledged
Financial assistance was provided by the Entomology Research Division US Department of Agriculture under Grant 12-14-100shy9187 (33)
CONTENTS Ganus Sennius Bridwell ___________________________________________ Phylogenetic goups within Sennius _______________________________ _
Characters _________ ________________________________________ Host plants distribution and evohtion ________________________ Relationships of groups _______________________________________
Species introduced into the United States _________________________ _ Key to Sennius speciet ___________________________________________ _ Systematics of Sennius __________________________________________ _
S abbreviatus (Say) ________________________________________ S altmiddoticola (Sharp) new combination _________ ________________ S atripectus new species _____________________________________ S auricomus new species ____________________________________ _ S breveapicalis (Pic) new combination _______________________ _ S celatus (Sharp) ___________________________ _______________ S chalcodermus new species _________________________________ _ S cruentatus (Horn) ________________________________________ S discolor (Horn) ___________________________________________ S durangensis new species __________________________________ _ S ensiculus new species _____________________________________ _ S fallax (Boheman) new combination _________________________ S guttifer (Sharp) new combination __________________________ S inanis (Sharp) new combination ____________________________ S incultellus new species ____________________________________ _ S infractus new species ______________________________________ S instabilis (Sharp) new combination ________________________ _ S laminifer (Sharp) new combination _______________________ _ S leucostauros new species ___________________________________ S medialis (Sharp) new combination __________________________ S militaris (Sharp) new lombination ________________________ _ S morosus (Sharp) 1 new combination __________________________ Sobesulus (Sharp) new combination __________________________ S russeolus new species _____________________________________ _ S sintulans (Schaeffer) ______________________________________ S trinotaticollis (Pic) 1 new combination _______________________ _ S whitei new species _______________________________________ _
Literature cited _________________________________________________ _ Appendix ______________________________________________________ _
Synonymicallist of Senni1S species ____________________________ Phylogenetic groups of Sennius species ________________________ _ Sennius species and their host plants __________________________ Plants attacked by Sennius species _____________________________
Page
1 6 6 6 7
12 12 17 17 22 24 26 29 31 36 38 43 47 50 54 58 61 64 67 68 72 75 78 81 84 88 91 93 96 99
102 104 104 105 106 108
1lt ~ ~
-tf ) L 0 7
The Leaf Mesophylls of Twenty Crops Their Light Spectra
and Opti cal and Geomet~ical Parameters
~ ~ ~ 0 amp-I p-I
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Technical Bulletin No 1465
~ ~ - I
Agricultural Research Service
UNITED STATES DEPARTMENT OF AGRICULTURE
In Cooperation With Texas Agricultural Experiment Station
Contents
Page Summary 1
Spectrophotometric measurements for seven
Spectrophotometric measurements at the
Correlations among spectrophotometric measurements and leaf-water content
Introduction 4 Materials and methods 8 Results and discussion 14 L~af water and thickness 14
selected wavelengths 20 Leaf spectra of four selected crops 22 Spectrophotometric measurements at the 550shy
nm wavelength 23
1OOO-nm wavelength 26
and thickness 27 Optical and geometrical leaf parameters 32
Literature cited 43 Appendix 46
Tables 46 Glossarv of terms 58
Issued March 1973
For sale by the Superintendent of Documents US Government Printing Office Washington DC 20402 - Price 50 cents domestic postpaid or
30 cents GPO Bookstore Stock Number 0100-02678
The Leaf Mesophylls of Twenty Crops Their Light Spectra and
Optical and Geometrical Parameters1
H W GAUSMAN pl1nt physiologist W A ALLEN research physicist C L WIEGAND soil scientist D E ESCOBAR biological laboratory techshyncian R R RODRIGUEZ phy~ical science technician and A J RICHARDSON physicist Southern Region AgriC1tltural Research Service United States Department 0 Agricultlre
Summary Leaf mesophylls among 20 agricultural crops are compared
with (1) Spectrophotometrically measured percent reflectances and transmittances and calculated absorptances of the leaves over the 500- to 2500-nanometer (nm) wavelength interval (2) percent leaf-water contents (3) leaf thickness measureshyments and (4) opthal and geometrical leaf parameters Data are given as averages of 10 leaves (replications) for each crop The crops are Avocado bean cantaloup corn cotton lettuce okra onion orange peach pepper pigweed pumpkin sorghum soybean sugarcane sunflower tomato watermelon and wheat
Thick succulent lettuce leaves had the highest water content (970 percent) and dorsiventral avocado orange and peach and compact sugarcane leaves had the lowest water contents (range 606 to 724 percent)
Soybean peach pumpkin and pigweed leaves were thinnest (range 0140 to 0170 mm) and sunflower cantaloup lettuce and onion leaves were thickest (range 0407 to 0978 mm)
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1350 nm) spectral regions Data for lettuce were omitted because the leaves sampled middotere immature
1 The work was supported in part by the National Aeronautics and Space Administration und~r NASA Contract No R-09-038-002 Current Code No 160-75-01-07-10
2 The authors acknowledge the histological and technical assistance of Guadalupe Cardona Marcia Schupp and Ron Bowen Thaks are extended to the Amul Company Development Center Weslaco Tex for 3upplying the bean and soybean plants
1
2 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
The mean reflectance of the crop leaves at the 550-nm waveshylength was 13 3 plusmn 28 percent (one standard deviation) The majority of crops fell within the 133 pound 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane leaves (162 to 186 percent)
At the 550-nm wavelength transmittances of orange tomato and avocado (19 to 55 percent) and okra soybean onion (148 to 188 percent) fell outside the 98 plusmn 42 percent range
The mean absorptance for the crops at 550-nm wavelength was 769 plusmn 58 percent Thirteen crops fell within the 769 plusmn 58 percent range Sugarcane onion bean and peppel leaves with low absorptance (692 to 706 percent) and peach tomato avoshycado and orange leaves with high absorptance (829 to 879 pershycent) fell outside the 769 plusmn 58 percent range The leaves with high absorptance had well-differentiated dorsiventral mesophylls with many chloroplasts in their palisade cells Leaves with low absorptance had poorly differentiated mesophylls-less distincshytion between palisade and spongy parenchyma cells
The 1OOO-nm wavelength was llsed to evaluate the influence of leaf-mesophyll arrangement on near-infrared (750 to 1350 nm) light reflectance The mean reflectance of the crop leaves at the IOOO-nm wavelength was 480 plusmn 39 percent The reflectance of onion (38) percent) and orange and bean (556 and 562 pershycent respectively) fell outside this range However only oneshyhalf of the tubular onion leaf (split longitudinally) was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn sugarcane and soybean leaves had the lowest reflectances (451 to 460 percent) and dOlsiventral bean orange and pepper leaves with very porous mesophyll had the highest reflectances (510 to 562 percent)
At the IOOO-nm wavelength the mean transmittance of all crop leaves was 479 plusmn 37 percent All crops fell within this rang-e except orange (389 percent) and bean (420 percent) and soybean pigweed and onion (522 to 540 percent)
The mean absorptance of all crop leaves at the 1000-nm waveshylength was 40 plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 pershycent) fell outside the 40 plusmn 17 percent range
Correlation coefficients equal to or larger than plusmn 0775 are conshysidered that accounted for at least 60 percent of the variation (0775 z x 100) between comparisons Negative coefficients exshyceeding - 0775 were obtained for correlations between light reshy
LEAF MESOPHYLLS OF TWENTY CROPS 3
flectance and percent leaf-water content for sugarcane at 1450- 1650- and 2200-nm for corn at 550- and 1450-nm for pigweed at 1450-nm and for tomato at 1450- and 2200-nm wavelengths Soybean had positive coefficients exceeding 0775 for the correlashytion between reflectance and leaf thickness at the 550- 800- and 1OOO-nm wavelengths and a negative coefficient that exshyceeded -077f5 for the correlation between transmittance and leaf thickness at the 1000-nm wavelength Soybean leaves also had large negative coefficients for the correlation between reshyflectance and leaf thickness at the 1450- 1950- and 2200-nm wavelengths and for the correlation between transmittance and leaf thickness at the 1450- 1650- 1950- and 2200-nm waveshylengths Peach pigweed tomato bean and onion crops also had high negative coefficients for t~e correlation between transmitshytance and leaf thickness at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths High positive coefficients were obtained for the correlation between leaf thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
The grams of water per cubic centimeter of leaf tissue were calculated for each crop leaf used except wheat There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue For transmittance coefficients exceeded -0775 only for okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and brams of water per cubic centimeter of leaf tissue gave high posishytive coefficients for okra leaves at 1450 1650 and 2200 nm
Experimental values of leaf reflectance and transmittance for the 20 crops have been transformed into effective optical conshystants Such optical constants are useful in the prediction of reshyflectance phenomena associated with leaves either stacked in a spectrophotometer or arranged naturally in a plant canopy The index of refraction n is plotted against wavelength to obtain disshypersion curves The values for the absorption coefficient k that are tabulated for the various crops are equivalent to values detershymined previously for leaves from agricultural crops
The dispersion curves of most of the crop leaves were reshymarkably similar in shape and in relatively close confidence bands Onion pigweed and lettuce were exceptions but only one-half of the tubular onion leaves (split longitudinally) was used lettuce leaves were immature and veins of pigweed leaves are surrounded by large cubical parenchymatous cells
4 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Sixteen of the 20 crops were analyzed to determine the thickshyness of water necessary to produce the observed leaf absorption and the number of identical compact layers into which the equivshyalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance Sugarcane corn sorghum and wheat leaves were not included because laborashytory determinations of thickness and water content were not made on entire leaves There was no statistically significant difshyference between observed and computed values for leaf water for 10 of the crops Pumpkin avocado okra tomato cantaloup and lettuce showed differences but they were not highly significant
The limiting value of reflectance from leaves piled sufficiently deep is termed infinite reflectance This parameter is a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed Infinite reflectance has been tabulated at 165 p for the 20 crops
Introduction To interpret remote-sensing data from aircraft and spacecraft
thE reflectance produced by features on the ~arths surface must be understood (33)3 The specific problem in agriculture is interpretation of reflectance produced by vegetation usuaIIy supershyimposed on a soil background Plant leaves yield most of the signal measured by remote sensors in aircraft a1 rl spacecraft Therefore they are of prime interest in characterizing vegetashytion and their interaction with electromagnetic radiation must be understood
The purpose of research reported here was to relate the leaf mesophyll structure of 20 important agricultural plant genera to their light spectra and to optical and geometrical parameters This report is a sequel to a technical monograph by Gausman and others (15) which presented research results on the spectralshyenergy relations of leaves for 11 plant genera characterized by marked differences in leaf-mesophyll arrangements The research was based on the hypothesis that leaf-mesophyll arrangements influence spectral-energy relations of leaves and plant canopies Previous research had considered only the relation of light reflecshytance to leaf surface morphologies (28) and to isobilateral leaves (18)
Plants studied were corn (Zea mays L) banana (Musa acuminata Colla (M cavendishii Lamb) I begonia (Begonia C1tshy
bull Italic numbers in partnthfSfR refer to Literature Cited p 43
LEAF MESOPHYLLS OF TWENTY CROPS 5
cullata Willd (E sernperlo1ens Link amp Otto) eucalyptus (Eucalllptus camaldulensis Dehnh (E rostrata Schlecht) rose (Rosa val unknown) l hyacinth (Eichhornia crassipes (Mart) Solms sedum (Sedum spectabile Boreau) ficus (Ficus elastica
~ Roxb ex Hornem) oleander (Nerium oleander L Ligustrum (Lig1lstrnm l1lcidum Ait) and crinum (Crinum fimbriat1llum Baker)
Differences in leaf mesophylls among the 11 plant genera (Hi) were compared with (1) Spectrophotometrically measured reshyflectance and transmittance and calculated absorptance values of the leaves over the 500- to 2500-nanometer (nm) 4 wavelength interval (2) percent leaf-water contents (oven-dry weight basis) (3) leaf-thickness measurements and (4) optical and geometrical leaf parameters
Percent leaf-water contents of the 11 plant genera ranged from nO percent for isolateral ~ (palisade layers on both sides) eucalypshytus to 95 percent for succulent sedum and begonia leaves with storage cells on each side of a central chlorenchyma
Dorsiventral rose and compact corn leaves (no palisade cells) were thinnest (about 015 mm) and succulent sedum leaves were thickest (about 082 mm)
Spectral data for upper (adaxial) and lower (abaxial) leaf surfaces of all genera for 550- 800- 1000- 1450- 1650- 1950- ann 2200-nm wavelengths were appended Spectra of upper leaf surfaces of oleander corn hyacinth and eucalyptus were charted At the 1000-nm wavelength diffuse reflectance was highest for dorsiventral oleander and lowest for compact corn leaves transmittance was lowest for oleander and highest for corn leaves and absorptance for corn and oleander leaves was approximately 3 and 9 percent respectively rhe compact corn leaf with low light reflectance and high transmittance has fewer intercellular air spaces than the dorsi ventral oleander leaf
Because the interaction of plant genera with wavelength was small mean spectral measurements of 550- 800- 1000- 1450- 1650- 1950- and 2200-nm wavelengths were compared Lower leaf surfaces of dorsi ventral leaves had higher reflectance values than upper leaf surfaces indicating that the spongy parenchyma contribute more to light scattering than the palisade parenchyma
bull Both nanometer (nm) and micron (p) are used here to denote spectral wavelengths A nanometer is one thousandth of a micron and a micron is one thousandth of a millimeter
bull Botanical terms are definpd in the Glossary of Terms p 58
6 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of the leaf mesophyll This was substantiated by equal reflectance values of upper and lower surfaces of compact corn leaves
Thick leaves of oleander crinum fi~us sedum and Iigustrum had the lowest percent transmittarce Mean spectrophotometrishycally measured transmittance values for the above wavelengths were lower when light was passed from the top through the leaves than when light was passed through from the bottom The difference jn transmittance was caused by greater light diffusion by upper leaf surfaces since the spectrophotometer used irradishyates the specimen with direct light
Diffuse reflectance data were made absolute by correcting for decay of the magnesium-oxide standard on the spectrophotomshyeter and absorptance was calculated as 100 - [percent reshyflectance + percent transmittance] When data for wavelengths were averaged highest absorptance values of 606 582 591 and 583 percent were obtained for the thick dorsiventral ficus crinum ligustrum and oleander leaves respectively and lowest values of 404 and 390 percent were obtained for the thin comshypact corn and thin dorsiventral rose leaves respectively
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1450 nm) regions respectively At the 550-nm wavelengths reflectance was greater from the lower surface than from the upper surface of dorsiventral leaves indicating that the chloroplasts in the palisade cells absorbed light Lower and upper surface reflectances were the same for the compact corn leaves Considering upper leaf surfaces only thick succulent sedum and thick ficus leaves had the highest and lowest reflecshytance values of 20 and 8 percent respectively
Percent transmittance was lowest for ficus and highest for succulent begonia leaves Compact leaves of corn and succulent leaves of sedum and begonia with essentially a continuous mesoshyphyll arrangement had the loyrest light absorptance of approxishymately 70 percent Thick dorsiventral leaves of ficus oleander and ligustrum with multiseriide epidermal layers or multishypalisade layers had the highest light absorptance of 80 to 90 percent
At the 1000-nm wavelength reflectance values from upper and lower leaf surface measurements were essentially alike Comshypact corn leaves had the lowest reflectance (43 percent) and succulent sedum and dorsi ventral ficus oleander ligustrum and crinum leaves had the highest reflectance (53 percent) The 350
7 LEAF MESOPHYLLS OF TWENTY CROPS
percent transmithnce of oleander leaves was lowest and 545 percent for corn was highest The thin corn and rose leaves had the lowest absorptance values (2 to 3 percent) and the thick leaves of ligustrum ficus crinum sed urn and oleander had the highest values (8 to 11 percent)
Correlation coefficients were considered that accounted for at least 60 percent of the variation (r2 x 100) between leaf thickness and reflectance leaf thickness and absorptance leaf-water conshytent and refiectance and leaf-water content and absorptance Oleander eucalyptus and hyacinth leaves gave the highest coshyefficients among the plant genera studied In general co~ efficients were negative between water content and reflectance and between thickness and reflectance measurements and middotvith the main exception of eucalyptus coefficients were positive beshytween leaf-water content and absorptance and between thickness and absorptance calculations at 1450- 1650- 1950- and 2200shynm wavelengths
Experimental values of leaf reflectance and transmittance for the 11 genera were transformed into effective optical constants Such optical constants are useful in the prediction of reflectance phenomena associated with leaves either stacked in a spectroshyphotometer or arranged naturally in a plant canopy The index of refraction n was plotted against wavelength to obtain disshypersion curves The absorption coefficient k was shown to be equivalent to values determined previously for leaves from agrishycultural crops
Each of the 11 genera has been analyzed to obtain geometrical parameters that specify the amount of water and air in the leaf The water parameter is the thickness of liquid water necessary to produce the observed leaf absorption Observed and computed valuesmiddot of leaf-water thickness were obtained Agreement was good except for ligustrum crinum and sedum The air paramshyeter is the number of identical compact layers into which the equivalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance
A third parameter infinite reflectance is observed when leaves are piled sufficiently deep Infinite reflectance was tabulated at L65 p for all 11 genera Infinite reflectance was shown to be a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed
The literatUre dealing with the interaction of light with plant leaves and leaf mesophyl1 structure is reviewed in the technical
8 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
monograph by Gausman and others (15) and is not repeated here Attention is directed however to the research of Aboukhaled 6 who related the optical properties of leaves to their energy-balance photosynthesis and water-use efficiency
Materials and Methods Twenty plant genera were selected that are presently economshy
ically important or have the potential of becoming valuable in the Texas Lower Rio Grande Valley Pigweed was considered here as a crop rather than a weed because it is used by some farmers as a plow-under or green-manure crop The leaves of A
the selected genera varied in mesophyll arrangement thickness water content and other structural differences such as palisadeshylayer arrangement Leaf characteristics of the 20 crops and the families they represent are indicated in table 1 and typical photomicrographs of leaf transections are depicted in figure 1
All plants were field grown in the summer of 1970 except that lettuce and onions were purchased fresh at a local market soybeans and beans were grown in a greenhouse and wheat was grown during the 1969 season
Ten mature and healthy-appearing leaves were sampled from each of the 20 plant genera Immediately after excision leaves were wrapped in Saran or Glad-Wrap to minimize dehydration Leaves were wiped with a slightly dampened cloth to remove surface contaminants before spectrophotometric measurements The tubular onion leaf was split longitudinally and only oneshyhalf was measured
A Beckman Model DK-2A spectrophotometer equipped with a reflectance attachment was used to measure spectral diffuse
bull Aboukhaled A Optical properties of leaves in relation to their energyshybalance photosynthesis and water use efficiency (PhD thesis) University of Calif Library Davis 139 pp 1966
7 Trade names are used in this pUblication solely for the purpose of providing specific information Mention of a trade name does not constitute a guarantee or warranty of the product by the US Department of Agriculture or an endorsement by the Department over other products not mentioned
FIGURE I-Photomicrographs of leaf transections of 20 plant genera differing in leaf thickness mesophyll arrangement and other gross structural characteristics A avocado S bean C cantaloup D corniE cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
9 LEAF MESOPHYLLS OF TWENTY CROPS
FIGURE I-Continued
10 TECHNICAL BULLETIN 1middot165 US DEPT OF AGRICULTURE
FIGURE I-Continued
LEAF MESOPHYLLS OF TWENTY CROPS 11
reflectance and transmittance on adaxial (uppel) surfaces of single leaves over the 500- to 2500-nm wavelength interval Data have 1ieen corrected for decay of the magnesium-oxide standard (27) to give absolute radiometric data Absorptance was calculated from the absolute values as Percent absorptance = 100 - (percent reflectance + percent transmittance)
Measurements of leaf thickness and diffuse reflectance and transmittance and fixation of tissue were completed within 6 hours after leaves were harvested or obtained for each genus
Leaf thickness was measured with a linear-displacement transshyducer and digital voltmeter (17) Leaf area was determined with a planimeter except that area per leaf of corn sorghum and sugarcane was calculated by the method of Slickter Wearden and Pauli (29) and area per leaf of cotton was calculated by Tohnsons method (20) Percent leaf-water content was detershymined on an oven-dry weight basis by drying at 68deg C for 72 hours and cooling in a desiccator before final weighing Leaf thickness and water-content determinations were not made on wheat leaves
Tissue pieces taken near the center of leaves approximately one-half inch on either side of the midrib were fixed in formalinshyacetic acid-alcohol dehydrated with a tertiary butanol series embedded in paraffin stained with either the safranin-fast green or the safranin-fast green-orange G combinations (19) and transversally microtomed at 12- or 14- thickness The relatively thick transverse sections were used to accentuate intercellular spaces and thus enhance differences in mesophyll arrangeshyments among the crops Photomicrographs were obtained with a Zeiss Standard Universal Photomicroscope
Spectrophotometrically measured reflectance and transmittance and calculated absorptance of seven wavelengths (550 800 1000 14)0 1650 1950 and 2200 nm) were analyzed for variance (W) Duncans Multiple Range Test (7) was used to test differshyences among means of the seven wavelengths at the 5-percent probability level Standard deviation was calculated to compare the leaf reflectance transmittance and absorptance of the crops at the 550- and 1000-nm wavelengths Coefficients were calcushylated to evaluate the correlation of leaf thickness with leaf-water content Coefficients were also obtained for correlations of reshyflectance transmittance and absorptance with grams of water per cubic centimeter of leaf tissue leaf-water content on an ovenshydry weight basis and leaf thickness Correlation coefficients of plusmn 0775 were chosen as levels of significance because they acshy
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
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30 170
ot EFlEeTCE~ FoO
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WAVELENGTH )
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FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
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17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
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REFUCTANCE
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18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
t)~ t-~ bull ~ Itmiddot
A Revision of the Genus Sennius of North and Central America
(ColeoF~ra Bruchidae)
Technic(l Bulletin No 1462
Agricultural Research Service UNITED STATES DEPARlMENT OF AGRICULTURE
in cooperation with Northern Arizona University
j
A Revision of the Genus Sennius of North and Central America
(Coleoptera Bruchidae)
Technical Bulletin No 1462
Agricultural Research Service UNITED STATES DEPARTMENT OF AGRICULTURE
in cooperation with Northern Arizona University
Washington DC Issued ]darch 1973
For sale by the Superintendent of Documents US Government Printing Office Washington DC - Price $175 domestic postpaid or $150 GPO Bookstore
Stock Number 6166-62656
~
ACKNOWLEDGMENTS
We thank the following persons for the generous loan of specishymens for this study R H Arnett Purdue University W F Barr University of Idaho D E Bright Canadian National Collection of Insects Ottawa H R Burke Texas A amp 11 University G W Byers University of Kansas O L Cartwright Smithsoniari Inshystitution Washington DC J B Chapin Louisiana State Univershysity J A Chemsak University of California Berkeley P J Clausen University of Minnesota H Dybas Field Museum of Natural History Chicago M Emsley Academy of Natural Scishyences Philadelphia S Frommer University of California Rivershyside F F Hasbrouck Arizona State University K L Hays Auburn University M T James Washington State University J D Lattin Oregon State University R J Lavigne University of Wyoming J F Lawrence Museum of Comparative Zoology Harvard University H B Leech California Academy of Sciences G H Nelson Kansas City College of Osteopathy and Surgery L L Pechuman Cornell University P C Peterson University of Nebraska E P Rouse University of Arkansas R R Snelling Los Angeles County Museum R T Thompson British Museum (Natural History) P H Timberlake University of California Riverside C A Triplehorn Ohio State University J D Unzicker Illinois State Natural History Survey G E Wallace Carnegie Museum Pittsburgh R L Wenzel Field Museum of Natural History Chicago F G Werner University of Arizona and D A Young North Carolina State University
For identifying the many plants collected during this study we thank R H Hevly and J M Rominger Northern Arizona Unishyversity and W H Lewis Missouri Botanical Garden
The figures were draWll by Miss Deborah Learned and Rosser Garrisoll Northern Arizona University and the junior author
Rodolpho Hernandez Corzo Director General Direccion General de la Fauna Silvestre Mexico DF was especially cooperative in procuring permits for collecting in Mexico His help is gratefully acknowledged
Financial assistance was provided by the Entomology Research Division US Department of Agriculture under Grant 12-14-100shy9187 (33)
CONTENTS Ganus Sennius Bridwell ___________________________________________ Phylogenetic goups within Sennius _______________________________ _
Characters _________ ________________________________________ Host plants distribution and evohtion ________________________ Relationships of groups _______________________________________
Species introduced into the United States _________________________ _ Key to Sennius speciet ___________________________________________ _ Systematics of Sennius __________________________________________ _
S abbreviatus (Say) ________________________________________ S altmiddoticola (Sharp) new combination _________ ________________ S atripectus new species _____________________________________ S auricomus new species ____________________________________ _ S breveapicalis (Pic) new combination _______________________ _ S celatus (Sharp) ___________________________ _______________ S chalcodermus new species _________________________________ _ S cruentatus (Horn) ________________________________________ S discolor (Horn) ___________________________________________ S durangensis new species __________________________________ _ S ensiculus new species _____________________________________ _ S fallax (Boheman) new combination _________________________ S guttifer (Sharp) new combination __________________________ S inanis (Sharp) new combination ____________________________ S incultellus new species ____________________________________ _ S infractus new species ______________________________________ S instabilis (Sharp) new combination ________________________ _ S laminifer (Sharp) new combination _______________________ _ S leucostauros new species ___________________________________ S medialis (Sharp) new combination __________________________ S militaris (Sharp) new lombination ________________________ _ S morosus (Sharp) 1 new combination __________________________ Sobesulus (Sharp) new combination __________________________ S russeolus new species _____________________________________ _ S sintulans (Schaeffer) ______________________________________ S trinotaticollis (Pic) 1 new combination _______________________ _ S whitei new species _______________________________________ _
Literature cited _________________________________________________ _ Appendix ______________________________________________________ _
Synonymicallist of Senni1S species ____________________________ Phylogenetic groups of Sennius species ________________________ _ Sennius species and their host plants __________________________ Plants attacked by Sennius species _____________________________
Page
1 6 6 6 7
12 12 17 17 22 24 26 29 31 36 38 43 47 50 54 58 61 64 67 68 72 75 78 81 84 88 91 93 96 99
102 104 104 105 106 108
1lt ~ ~
-tf ) L 0 7
The Leaf Mesophylls of Twenty Crops Their Light Spectra
and Opti cal and Geomet~ical Parameters
~ ~ ~ 0 amp-I p-I
ll1 O
~ ~
~ ~
(lt) r-shyt
r
0gt1
c- CL lt
- ~((7J r ~ 1-4
- ~ ~~ p shy
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Technical Bulletin No 1465
~ ~ - I
Agricultural Research Service
UNITED STATES DEPARTMENT OF AGRICULTURE
In Cooperation With Texas Agricultural Experiment Station
Contents
Page Summary 1
Spectrophotometric measurements for seven
Spectrophotometric measurements at the
Correlations among spectrophotometric measurements and leaf-water content
Introduction 4 Materials and methods 8 Results and discussion 14 L~af water and thickness 14
selected wavelengths 20 Leaf spectra of four selected crops 22 Spectrophotometric measurements at the 550shy
nm wavelength 23
1OOO-nm wavelength 26
and thickness 27 Optical and geometrical leaf parameters 32
Literature cited 43 Appendix 46
Tables 46 Glossarv of terms 58
Issued March 1973
For sale by the Superintendent of Documents US Government Printing Office Washington DC 20402 - Price 50 cents domestic postpaid or
30 cents GPO Bookstore Stock Number 0100-02678
The Leaf Mesophylls of Twenty Crops Their Light Spectra and
Optical and Geometrical Parameters1
H W GAUSMAN pl1nt physiologist W A ALLEN research physicist C L WIEGAND soil scientist D E ESCOBAR biological laboratory techshyncian R R RODRIGUEZ phy~ical science technician and A J RICHARDSON physicist Southern Region AgriC1tltural Research Service United States Department 0 Agricultlre
Summary Leaf mesophylls among 20 agricultural crops are compared
with (1) Spectrophotometrically measured percent reflectances and transmittances and calculated absorptances of the leaves over the 500- to 2500-nanometer (nm) wavelength interval (2) percent leaf-water contents (3) leaf thickness measureshyments and (4) opthal and geometrical leaf parameters Data are given as averages of 10 leaves (replications) for each crop The crops are Avocado bean cantaloup corn cotton lettuce okra onion orange peach pepper pigweed pumpkin sorghum soybean sugarcane sunflower tomato watermelon and wheat
Thick succulent lettuce leaves had the highest water content (970 percent) and dorsiventral avocado orange and peach and compact sugarcane leaves had the lowest water contents (range 606 to 724 percent)
Soybean peach pumpkin and pigweed leaves were thinnest (range 0140 to 0170 mm) and sunflower cantaloup lettuce and onion leaves were thickest (range 0407 to 0978 mm)
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1350 nm) spectral regions Data for lettuce were omitted because the leaves sampled middotere immature
1 The work was supported in part by the National Aeronautics and Space Administration und~r NASA Contract No R-09-038-002 Current Code No 160-75-01-07-10
2 The authors acknowledge the histological and technical assistance of Guadalupe Cardona Marcia Schupp and Ron Bowen Thaks are extended to the Amul Company Development Center Weslaco Tex for 3upplying the bean and soybean plants
1
2 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
The mean reflectance of the crop leaves at the 550-nm waveshylength was 13 3 plusmn 28 percent (one standard deviation) The majority of crops fell within the 133 pound 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane leaves (162 to 186 percent)
At the 550-nm wavelength transmittances of orange tomato and avocado (19 to 55 percent) and okra soybean onion (148 to 188 percent) fell outside the 98 plusmn 42 percent range
The mean absorptance for the crops at 550-nm wavelength was 769 plusmn 58 percent Thirteen crops fell within the 769 plusmn 58 percent range Sugarcane onion bean and peppel leaves with low absorptance (692 to 706 percent) and peach tomato avoshycado and orange leaves with high absorptance (829 to 879 pershycent) fell outside the 769 plusmn 58 percent range The leaves with high absorptance had well-differentiated dorsiventral mesophylls with many chloroplasts in their palisade cells Leaves with low absorptance had poorly differentiated mesophylls-less distincshytion between palisade and spongy parenchyma cells
The 1OOO-nm wavelength was llsed to evaluate the influence of leaf-mesophyll arrangement on near-infrared (750 to 1350 nm) light reflectance The mean reflectance of the crop leaves at the IOOO-nm wavelength was 480 plusmn 39 percent The reflectance of onion (38) percent) and orange and bean (556 and 562 pershycent respectively) fell outside this range However only oneshyhalf of the tubular onion leaf (split longitudinally) was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn sugarcane and soybean leaves had the lowest reflectances (451 to 460 percent) and dOlsiventral bean orange and pepper leaves with very porous mesophyll had the highest reflectances (510 to 562 percent)
At the IOOO-nm wavelength the mean transmittance of all crop leaves was 479 plusmn 37 percent All crops fell within this rang-e except orange (389 percent) and bean (420 percent) and soybean pigweed and onion (522 to 540 percent)
The mean absorptance of all crop leaves at the 1000-nm waveshylength was 40 plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 pershycent) fell outside the 40 plusmn 17 percent range
Correlation coefficients equal to or larger than plusmn 0775 are conshysidered that accounted for at least 60 percent of the variation (0775 z x 100) between comparisons Negative coefficients exshyceeding - 0775 were obtained for correlations between light reshy
LEAF MESOPHYLLS OF TWENTY CROPS 3
flectance and percent leaf-water content for sugarcane at 1450- 1650- and 2200-nm for corn at 550- and 1450-nm for pigweed at 1450-nm and for tomato at 1450- and 2200-nm wavelengths Soybean had positive coefficients exceeding 0775 for the correlashytion between reflectance and leaf thickness at the 550- 800- and 1OOO-nm wavelengths and a negative coefficient that exshyceeded -077f5 for the correlation between transmittance and leaf thickness at the 1000-nm wavelength Soybean leaves also had large negative coefficients for the correlation between reshyflectance and leaf thickness at the 1450- 1950- and 2200-nm wavelengths and for the correlation between transmittance and leaf thickness at the 1450- 1650- 1950- and 2200-nm waveshylengths Peach pigweed tomato bean and onion crops also had high negative coefficients for t~e correlation between transmitshytance and leaf thickness at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths High positive coefficients were obtained for the correlation between leaf thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
The grams of water per cubic centimeter of leaf tissue were calculated for each crop leaf used except wheat There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue For transmittance coefficients exceeded -0775 only for okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and brams of water per cubic centimeter of leaf tissue gave high posishytive coefficients for okra leaves at 1450 1650 and 2200 nm
Experimental values of leaf reflectance and transmittance for the 20 crops have been transformed into effective optical conshystants Such optical constants are useful in the prediction of reshyflectance phenomena associated with leaves either stacked in a spectrophotometer or arranged naturally in a plant canopy The index of refraction n is plotted against wavelength to obtain disshypersion curves The values for the absorption coefficient k that are tabulated for the various crops are equivalent to values detershymined previously for leaves from agricultural crops
The dispersion curves of most of the crop leaves were reshymarkably similar in shape and in relatively close confidence bands Onion pigweed and lettuce were exceptions but only one-half of the tubular onion leaves (split longitudinally) was used lettuce leaves were immature and veins of pigweed leaves are surrounded by large cubical parenchymatous cells
4 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Sixteen of the 20 crops were analyzed to determine the thickshyness of water necessary to produce the observed leaf absorption and the number of identical compact layers into which the equivshyalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance Sugarcane corn sorghum and wheat leaves were not included because laborashytory determinations of thickness and water content were not made on entire leaves There was no statistically significant difshyference between observed and computed values for leaf water for 10 of the crops Pumpkin avocado okra tomato cantaloup and lettuce showed differences but they were not highly significant
The limiting value of reflectance from leaves piled sufficiently deep is termed infinite reflectance This parameter is a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed Infinite reflectance has been tabulated at 165 p for the 20 crops
Introduction To interpret remote-sensing data from aircraft and spacecraft
thE reflectance produced by features on the ~arths surface must be understood (33)3 The specific problem in agriculture is interpretation of reflectance produced by vegetation usuaIIy supershyimposed on a soil background Plant leaves yield most of the signal measured by remote sensors in aircraft a1 rl spacecraft Therefore they are of prime interest in characterizing vegetashytion and their interaction with electromagnetic radiation must be understood
The purpose of research reported here was to relate the leaf mesophyll structure of 20 important agricultural plant genera to their light spectra and to optical and geometrical parameters This report is a sequel to a technical monograph by Gausman and others (15) which presented research results on the spectralshyenergy relations of leaves for 11 plant genera characterized by marked differences in leaf-mesophyll arrangements The research was based on the hypothesis that leaf-mesophyll arrangements influence spectral-energy relations of leaves and plant canopies Previous research had considered only the relation of light reflecshytance to leaf surface morphologies (28) and to isobilateral leaves (18)
Plants studied were corn (Zea mays L) banana (Musa acuminata Colla (M cavendishii Lamb) I begonia (Begonia C1tshy
bull Italic numbers in partnthfSfR refer to Literature Cited p 43
LEAF MESOPHYLLS OF TWENTY CROPS 5
cullata Willd (E sernperlo1ens Link amp Otto) eucalyptus (Eucalllptus camaldulensis Dehnh (E rostrata Schlecht) rose (Rosa val unknown) l hyacinth (Eichhornia crassipes (Mart) Solms sedum (Sedum spectabile Boreau) ficus (Ficus elastica
~ Roxb ex Hornem) oleander (Nerium oleander L Ligustrum (Lig1lstrnm l1lcidum Ait) and crinum (Crinum fimbriat1llum Baker)
Differences in leaf mesophylls among the 11 plant genera (Hi) were compared with (1) Spectrophotometrically measured reshyflectance and transmittance and calculated absorptance values of the leaves over the 500- to 2500-nanometer (nm) 4 wavelength interval (2) percent leaf-water contents (oven-dry weight basis) (3) leaf-thickness measurements and (4) optical and geometrical leaf parameters
Percent leaf-water contents of the 11 plant genera ranged from nO percent for isolateral ~ (palisade layers on both sides) eucalypshytus to 95 percent for succulent sedum and begonia leaves with storage cells on each side of a central chlorenchyma
Dorsiventral rose and compact corn leaves (no palisade cells) were thinnest (about 015 mm) and succulent sedum leaves were thickest (about 082 mm)
Spectral data for upper (adaxial) and lower (abaxial) leaf surfaces of all genera for 550- 800- 1000- 1450- 1650- 1950- ann 2200-nm wavelengths were appended Spectra of upper leaf surfaces of oleander corn hyacinth and eucalyptus were charted At the 1000-nm wavelength diffuse reflectance was highest for dorsiventral oleander and lowest for compact corn leaves transmittance was lowest for oleander and highest for corn leaves and absorptance for corn and oleander leaves was approximately 3 and 9 percent respectively rhe compact corn leaf with low light reflectance and high transmittance has fewer intercellular air spaces than the dorsi ventral oleander leaf
Because the interaction of plant genera with wavelength was small mean spectral measurements of 550- 800- 1000- 1450- 1650- 1950- and 2200-nm wavelengths were compared Lower leaf surfaces of dorsi ventral leaves had higher reflectance values than upper leaf surfaces indicating that the spongy parenchyma contribute more to light scattering than the palisade parenchyma
bull Both nanometer (nm) and micron (p) are used here to denote spectral wavelengths A nanometer is one thousandth of a micron and a micron is one thousandth of a millimeter
bull Botanical terms are definpd in the Glossary of Terms p 58
6 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of the leaf mesophyll This was substantiated by equal reflectance values of upper and lower surfaces of compact corn leaves
Thick leaves of oleander crinum fi~us sedum and Iigustrum had the lowest percent transmittarce Mean spectrophotometrishycally measured transmittance values for the above wavelengths were lower when light was passed from the top through the leaves than when light was passed through from the bottom The difference jn transmittance was caused by greater light diffusion by upper leaf surfaces since the spectrophotometer used irradishyates the specimen with direct light
Diffuse reflectance data were made absolute by correcting for decay of the magnesium-oxide standard on the spectrophotomshyeter and absorptance was calculated as 100 - [percent reshyflectance + percent transmittance] When data for wavelengths were averaged highest absorptance values of 606 582 591 and 583 percent were obtained for the thick dorsiventral ficus crinum ligustrum and oleander leaves respectively and lowest values of 404 and 390 percent were obtained for the thin comshypact corn and thin dorsiventral rose leaves respectively
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1450 nm) regions respectively At the 550-nm wavelengths reflectance was greater from the lower surface than from the upper surface of dorsiventral leaves indicating that the chloroplasts in the palisade cells absorbed light Lower and upper surface reflectances were the same for the compact corn leaves Considering upper leaf surfaces only thick succulent sedum and thick ficus leaves had the highest and lowest reflecshytance values of 20 and 8 percent respectively
Percent transmittance was lowest for ficus and highest for succulent begonia leaves Compact leaves of corn and succulent leaves of sedum and begonia with essentially a continuous mesoshyphyll arrangement had the loyrest light absorptance of approxishymately 70 percent Thick dorsiventral leaves of ficus oleander and ligustrum with multiseriide epidermal layers or multishypalisade layers had the highest light absorptance of 80 to 90 percent
At the 1000-nm wavelength reflectance values from upper and lower leaf surface measurements were essentially alike Comshypact corn leaves had the lowest reflectance (43 percent) and succulent sedum and dorsi ventral ficus oleander ligustrum and crinum leaves had the highest reflectance (53 percent) The 350
7 LEAF MESOPHYLLS OF TWENTY CROPS
percent transmithnce of oleander leaves was lowest and 545 percent for corn was highest The thin corn and rose leaves had the lowest absorptance values (2 to 3 percent) and the thick leaves of ligustrum ficus crinum sed urn and oleander had the highest values (8 to 11 percent)
Correlation coefficients were considered that accounted for at least 60 percent of the variation (r2 x 100) between leaf thickness and reflectance leaf thickness and absorptance leaf-water conshytent and refiectance and leaf-water content and absorptance Oleander eucalyptus and hyacinth leaves gave the highest coshyefficients among the plant genera studied In general co~ efficients were negative between water content and reflectance and between thickness and reflectance measurements and middotvith the main exception of eucalyptus coefficients were positive beshytween leaf-water content and absorptance and between thickness and absorptance calculations at 1450- 1650- 1950- and 2200shynm wavelengths
Experimental values of leaf reflectance and transmittance for the 11 genera were transformed into effective optical constants Such optical constants are useful in the prediction of reflectance phenomena associated with leaves either stacked in a spectroshyphotometer or arranged naturally in a plant canopy The index of refraction n was plotted against wavelength to obtain disshypersion curves The absorption coefficient k was shown to be equivalent to values determined previously for leaves from agrishycultural crops
Each of the 11 genera has been analyzed to obtain geometrical parameters that specify the amount of water and air in the leaf The water parameter is the thickness of liquid water necessary to produce the observed leaf absorption Observed and computed valuesmiddot of leaf-water thickness were obtained Agreement was good except for ligustrum crinum and sedum The air paramshyeter is the number of identical compact layers into which the equivalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance
A third parameter infinite reflectance is observed when leaves are piled sufficiently deep Infinite reflectance was tabulated at L65 p for all 11 genera Infinite reflectance was shown to be a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed
The literatUre dealing with the interaction of light with plant leaves and leaf mesophyl1 structure is reviewed in the technical
8 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
monograph by Gausman and others (15) and is not repeated here Attention is directed however to the research of Aboukhaled 6 who related the optical properties of leaves to their energy-balance photosynthesis and water-use efficiency
Materials and Methods Twenty plant genera were selected that are presently economshy
ically important or have the potential of becoming valuable in the Texas Lower Rio Grande Valley Pigweed was considered here as a crop rather than a weed because it is used by some farmers as a plow-under or green-manure crop The leaves of A
the selected genera varied in mesophyll arrangement thickness water content and other structural differences such as palisadeshylayer arrangement Leaf characteristics of the 20 crops and the families they represent are indicated in table 1 and typical photomicrographs of leaf transections are depicted in figure 1
All plants were field grown in the summer of 1970 except that lettuce and onions were purchased fresh at a local market soybeans and beans were grown in a greenhouse and wheat was grown during the 1969 season
Ten mature and healthy-appearing leaves were sampled from each of the 20 plant genera Immediately after excision leaves were wrapped in Saran or Glad-Wrap to minimize dehydration Leaves were wiped with a slightly dampened cloth to remove surface contaminants before spectrophotometric measurements The tubular onion leaf was split longitudinally and only oneshyhalf was measured
A Beckman Model DK-2A spectrophotometer equipped with a reflectance attachment was used to measure spectral diffuse
bull Aboukhaled A Optical properties of leaves in relation to their energyshybalance photosynthesis and water use efficiency (PhD thesis) University of Calif Library Davis 139 pp 1966
7 Trade names are used in this pUblication solely for the purpose of providing specific information Mention of a trade name does not constitute a guarantee or warranty of the product by the US Department of Agriculture or an endorsement by the Department over other products not mentioned
FIGURE I-Photomicrographs of leaf transections of 20 plant genera differing in leaf thickness mesophyll arrangement and other gross structural characteristics A avocado S bean C cantaloup D corniE cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
9 LEAF MESOPHYLLS OF TWENTY CROPS
FIGURE I-Continued
10 TECHNICAL BULLETIN 1middot165 US DEPT OF AGRICULTURE
FIGURE I-Continued
LEAF MESOPHYLLS OF TWENTY CROPS 11
reflectance and transmittance on adaxial (uppel) surfaces of single leaves over the 500- to 2500-nm wavelength interval Data have 1ieen corrected for decay of the magnesium-oxide standard (27) to give absolute radiometric data Absorptance was calculated from the absolute values as Percent absorptance = 100 - (percent reflectance + percent transmittance)
Measurements of leaf thickness and diffuse reflectance and transmittance and fixation of tissue were completed within 6 hours after leaves were harvested or obtained for each genus
Leaf thickness was measured with a linear-displacement transshyducer and digital voltmeter (17) Leaf area was determined with a planimeter except that area per leaf of corn sorghum and sugarcane was calculated by the method of Slickter Wearden and Pauli (29) and area per leaf of cotton was calculated by Tohnsons method (20) Percent leaf-water content was detershymined on an oven-dry weight basis by drying at 68deg C for 72 hours and cooling in a desiccator before final weighing Leaf thickness and water-content determinations were not made on wheat leaves
Tissue pieces taken near the center of leaves approximately one-half inch on either side of the midrib were fixed in formalinshyacetic acid-alcohol dehydrated with a tertiary butanol series embedded in paraffin stained with either the safranin-fast green or the safranin-fast green-orange G combinations (19) and transversally microtomed at 12- or 14- thickness The relatively thick transverse sections were used to accentuate intercellular spaces and thus enhance differences in mesophyll arrangeshyments among the crops Photomicrographs were obtained with a Zeiss Standard Universal Photomicroscope
Spectrophotometrically measured reflectance and transmittance and calculated absorptance of seven wavelengths (550 800 1000 14)0 1650 1950 and 2200 nm) were analyzed for variance (W) Duncans Multiple Range Test (7) was used to test differshyences among means of the seven wavelengths at the 5-percent probability level Standard deviation was calculated to compare the leaf reflectance transmittance and absorptance of the crops at the 550- and 1000-nm wavelengths Coefficients were calcushylated to evaluate the correlation of leaf thickness with leaf-water content Coefficients were also obtained for correlations of reshyflectance transmittance and absorptance with grams of water per cubic centimeter of leaf tissue leaf-water content on an ovenshydry weight basis and leaf thickness Correlation coefficients of plusmn 0775 were chosen as levels of significance because they acshy
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
~ID~O~O~--~i500~I~__~W~~--~aoo
500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
100 10
TRAHSiMTlAHCE
20
i i
401 ~ 1 ~
O ~
70
SO ~ REFLpoundCT~ 00
o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
N
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
p
500 1000 -~------- ~o
100
140
~50 460 170 -j80
90
0 RJOO
o---middotiir-~LiOo----2000L---2100
R
IDO~ 100
TRANSMfTTANCE
i ~
A8SORPT~CE
~~ 1 80 j
III REFLpoundCTANC( 90
Dshy~
aa
T
o
o~
Q
70 i 60~
I
~ ~u 201shy
bull Ill
o~
s
1000
IOO
wlllVflfJrtGTH fWI)
--oDIGTl1
~o
REFUclANCE
FIGURE 2-Continued
_~
2DOO
(HOO __--J
Z300
2gt00
10
120 1 30
1 ~ ~o ~ 60
10
bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
j
A Revision of the Genus Sennius of North and Central America
(Coleoptera Bruchidae)
Technical Bulletin No 1462
Agricultural Research Service UNITED STATES DEPARTMENT OF AGRICULTURE
in cooperation with Northern Arizona University
Washington DC Issued ]darch 1973
For sale by the Superintendent of Documents US Government Printing Office Washington DC - Price $175 domestic postpaid or $150 GPO Bookstore
Stock Number 6166-62656
~
ACKNOWLEDGMENTS
We thank the following persons for the generous loan of specishymens for this study R H Arnett Purdue University W F Barr University of Idaho D E Bright Canadian National Collection of Insects Ottawa H R Burke Texas A amp 11 University G W Byers University of Kansas O L Cartwright Smithsoniari Inshystitution Washington DC J B Chapin Louisiana State Univershysity J A Chemsak University of California Berkeley P J Clausen University of Minnesota H Dybas Field Museum of Natural History Chicago M Emsley Academy of Natural Scishyences Philadelphia S Frommer University of California Rivershyside F F Hasbrouck Arizona State University K L Hays Auburn University M T James Washington State University J D Lattin Oregon State University R J Lavigne University of Wyoming J F Lawrence Museum of Comparative Zoology Harvard University H B Leech California Academy of Sciences G H Nelson Kansas City College of Osteopathy and Surgery L L Pechuman Cornell University P C Peterson University of Nebraska E P Rouse University of Arkansas R R Snelling Los Angeles County Museum R T Thompson British Museum (Natural History) P H Timberlake University of California Riverside C A Triplehorn Ohio State University J D Unzicker Illinois State Natural History Survey G E Wallace Carnegie Museum Pittsburgh R L Wenzel Field Museum of Natural History Chicago F G Werner University of Arizona and D A Young North Carolina State University
For identifying the many plants collected during this study we thank R H Hevly and J M Rominger Northern Arizona Unishyversity and W H Lewis Missouri Botanical Garden
The figures were draWll by Miss Deborah Learned and Rosser Garrisoll Northern Arizona University and the junior author
Rodolpho Hernandez Corzo Director General Direccion General de la Fauna Silvestre Mexico DF was especially cooperative in procuring permits for collecting in Mexico His help is gratefully acknowledged
Financial assistance was provided by the Entomology Research Division US Department of Agriculture under Grant 12-14-100shy9187 (33)
CONTENTS Ganus Sennius Bridwell ___________________________________________ Phylogenetic goups within Sennius _______________________________ _
Characters _________ ________________________________________ Host plants distribution and evohtion ________________________ Relationships of groups _______________________________________
Species introduced into the United States _________________________ _ Key to Sennius speciet ___________________________________________ _ Systematics of Sennius __________________________________________ _
S abbreviatus (Say) ________________________________________ S altmiddoticola (Sharp) new combination _________ ________________ S atripectus new species _____________________________________ S auricomus new species ____________________________________ _ S breveapicalis (Pic) new combination _______________________ _ S celatus (Sharp) ___________________________ _______________ S chalcodermus new species _________________________________ _ S cruentatus (Horn) ________________________________________ S discolor (Horn) ___________________________________________ S durangensis new species __________________________________ _ S ensiculus new species _____________________________________ _ S fallax (Boheman) new combination _________________________ S guttifer (Sharp) new combination __________________________ S inanis (Sharp) new combination ____________________________ S incultellus new species ____________________________________ _ S infractus new species ______________________________________ S instabilis (Sharp) new combination ________________________ _ S laminifer (Sharp) new combination _______________________ _ S leucostauros new species ___________________________________ S medialis (Sharp) new combination __________________________ S militaris (Sharp) new lombination ________________________ _ S morosus (Sharp) 1 new combination __________________________ Sobesulus (Sharp) new combination __________________________ S russeolus new species _____________________________________ _ S sintulans (Schaeffer) ______________________________________ S trinotaticollis (Pic) 1 new combination _______________________ _ S whitei new species _______________________________________ _
Literature cited _________________________________________________ _ Appendix ______________________________________________________ _
Synonymicallist of Senni1S species ____________________________ Phylogenetic groups of Sennius species ________________________ _ Sennius species and their host plants __________________________ Plants attacked by Sennius species _____________________________
Page
1 6 6 6 7
12 12 17 17 22 24 26 29 31 36 38 43 47 50 54 58 61 64 67 68 72 75 78 81 84 88 91 93 96 99
102 104 104 105 106 108
1lt ~ ~
-tf ) L 0 7
The Leaf Mesophylls of Twenty Crops Their Light Spectra
and Opti cal and Geomet~ical Parameters
~ ~ ~ 0 amp-I p-I
ll1 O
~ ~
~ ~
(lt) r-shyt
r
0gt1
c- CL lt
- ~((7J r ~ 1-4
- ~ ~~ p shy
c (
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( ~
Technical Bulletin No 1465
~ ~ - I
Agricultural Research Service
UNITED STATES DEPARTMENT OF AGRICULTURE
In Cooperation With Texas Agricultural Experiment Station
Contents
Page Summary 1
Spectrophotometric measurements for seven
Spectrophotometric measurements at the
Correlations among spectrophotometric measurements and leaf-water content
Introduction 4 Materials and methods 8 Results and discussion 14 L~af water and thickness 14
selected wavelengths 20 Leaf spectra of four selected crops 22 Spectrophotometric measurements at the 550shy
nm wavelength 23
1OOO-nm wavelength 26
and thickness 27 Optical and geometrical leaf parameters 32
Literature cited 43 Appendix 46
Tables 46 Glossarv of terms 58
Issued March 1973
For sale by the Superintendent of Documents US Government Printing Office Washington DC 20402 - Price 50 cents domestic postpaid or
30 cents GPO Bookstore Stock Number 0100-02678
The Leaf Mesophylls of Twenty Crops Their Light Spectra and
Optical and Geometrical Parameters1
H W GAUSMAN pl1nt physiologist W A ALLEN research physicist C L WIEGAND soil scientist D E ESCOBAR biological laboratory techshyncian R R RODRIGUEZ phy~ical science technician and A J RICHARDSON physicist Southern Region AgriC1tltural Research Service United States Department 0 Agricultlre
Summary Leaf mesophylls among 20 agricultural crops are compared
with (1) Spectrophotometrically measured percent reflectances and transmittances and calculated absorptances of the leaves over the 500- to 2500-nanometer (nm) wavelength interval (2) percent leaf-water contents (3) leaf thickness measureshyments and (4) opthal and geometrical leaf parameters Data are given as averages of 10 leaves (replications) for each crop The crops are Avocado bean cantaloup corn cotton lettuce okra onion orange peach pepper pigweed pumpkin sorghum soybean sugarcane sunflower tomato watermelon and wheat
Thick succulent lettuce leaves had the highest water content (970 percent) and dorsiventral avocado orange and peach and compact sugarcane leaves had the lowest water contents (range 606 to 724 percent)
Soybean peach pumpkin and pigweed leaves were thinnest (range 0140 to 0170 mm) and sunflower cantaloup lettuce and onion leaves were thickest (range 0407 to 0978 mm)
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1350 nm) spectral regions Data for lettuce were omitted because the leaves sampled middotere immature
1 The work was supported in part by the National Aeronautics and Space Administration und~r NASA Contract No R-09-038-002 Current Code No 160-75-01-07-10
2 The authors acknowledge the histological and technical assistance of Guadalupe Cardona Marcia Schupp and Ron Bowen Thaks are extended to the Amul Company Development Center Weslaco Tex for 3upplying the bean and soybean plants
1
2 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
The mean reflectance of the crop leaves at the 550-nm waveshylength was 13 3 plusmn 28 percent (one standard deviation) The majority of crops fell within the 133 pound 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane leaves (162 to 186 percent)
At the 550-nm wavelength transmittances of orange tomato and avocado (19 to 55 percent) and okra soybean onion (148 to 188 percent) fell outside the 98 plusmn 42 percent range
The mean absorptance for the crops at 550-nm wavelength was 769 plusmn 58 percent Thirteen crops fell within the 769 plusmn 58 percent range Sugarcane onion bean and peppel leaves with low absorptance (692 to 706 percent) and peach tomato avoshycado and orange leaves with high absorptance (829 to 879 pershycent) fell outside the 769 plusmn 58 percent range The leaves with high absorptance had well-differentiated dorsiventral mesophylls with many chloroplasts in their palisade cells Leaves with low absorptance had poorly differentiated mesophylls-less distincshytion between palisade and spongy parenchyma cells
The 1OOO-nm wavelength was llsed to evaluate the influence of leaf-mesophyll arrangement on near-infrared (750 to 1350 nm) light reflectance The mean reflectance of the crop leaves at the IOOO-nm wavelength was 480 plusmn 39 percent The reflectance of onion (38) percent) and orange and bean (556 and 562 pershycent respectively) fell outside this range However only oneshyhalf of the tubular onion leaf (split longitudinally) was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn sugarcane and soybean leaves had the lowest reflectances (451 to 460 percent) and dOlsiventral bean orange and pepper leaves with very porous mesophyll had the highest reflectances (510 to 562 percent)
At the IOOO-nm wavelength the mean transmittance of all crop leaves was 479 plusmn 37 percent All crops fell within this rang-e except orange (389 percent) and bean (420 percent) and soybean pigweed and onion (522 to 540 percent)
The mean absorptance of all crop leaves at the 1000-nm waveshylength was 40 plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 pershycent) fell outside the 40 plusmn 17 percent range
Correlation coefficients equal to or larger than plusmn 0775 are conshysidered that accounted for at least 60 percent of the variation (0775 z x 100) between comparisons Negative coefficients exshyceeding - 0775 were obtained for correlations between light reshy
LEAF MESOPHYLLS OF TWENTY CROPS 3
flectance and percent leaf-water content for sugarcane at 1450- 1650- and 2200-nm for corn at 550- and 1450-nm for pigweed at 1450-nm and for tomato at 1450- and 2200-nm wavelengths Soybean had positive coefficients exceeding 0775 for the correlashytion between reflectance and leaf thickness at the 550- 800- and 1OOO-nm wavelengths and a negative coefficient that exshyceeded -077f5 for the correlation between transmittance and leaf thickness at the 1000-nm wavelength Soybean leaves also had large negative coefficients for the correlation between reshyflectance and leaf thickness at the 1450- 1950- and 2200-nm wavelengths and for the correlation between transmittance and leaf thickness at the 1450- 1650- 1950- and 2200-nm waveshylengths Peach pigweed tomato bean and onion crops also had high negative coefficients for t~e correlation between transmitshytance and leaf thickness at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths High positive coefficients were obtained for the correlation between leaf thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
The grams of water per cubic centimeter of leaf tissue were calculated for each crop leaf used except wheat There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue For transmittance coefficients exceeded -0775 only for okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and brams of water per cubic centimeter of leaf tissue gave high posishytive coefficients for okra leaves at 1450 1650 and 2200 nm
Experimental values of leaf reflectance and transmittance for the 20 crops have been transformed into effective optical conshystants Such optical constants are useful in the prediction of reshyflectance phenomena associated with leaves either stacked in a spectrophotometer or arranged naturally in a plant canopy The index of refraction n is plotted against wavelength to obtain disshypersion curves The values for the absorption coefficient k that are tabulated for the various crops are equivalent to values detershymined previously for leaves from agricultural crops
The dispersion curves of most of the crop leaves were reshymarkably similar in shape and in relatively close confidence bands Onion pigweed and lettuce were exceptions but only one-half of the tubular onion leaves (split longitudinally) was used lettuce leaves were immature and veins of pigweed leaves are surrounded by large cubical parenchymatous cells
4 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Sixteen of the 20 crops were analyzed to determine the thickshyness of water necessary to produce the observed leaf absorption and the number of identical compact layers into which the equivshyalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance Sugarcane corn sorghum and wheat leaves were not included because laborashytory determinations of thickness and water content were not made on entire leaves There was no statistically significant difshyference between observed and computed values for leaf water for 10 of the crops Pumpkin avocado okra tomato cantaloup and lettuce showed differences but they were not highly significant
The limiting value of reflectance from leaves piled sufficiently deep is termed infinite reflectance This parameter is a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed Infinite reflectance has been tabulated at 165 p for the 20 crops
Introduction To interpret remote-sensing data from aircraft and spacecraft
thE reflectance produced by features on the ~arths surface must be understood (33)3 The specific problem in agriculture is interpretation of reflectance produced by vegetation usuaIIy supershyimposed on a soil background Plant leaves yield most of the signal measured by remote sensors in aircraft a1 rl spacecraft Therefore they are of prime interest in characterizing vegetashytion and their interaction with electromagnetic radiation must be understood
The purpose of research reported here was to relate the leaf mesophyll structure of 20 important agricultural plant genera to their light spectra and to optical and geometrical parameters This report is a sequel to a technical monograph by Gausman and others (15) which presented research results on the spectralshyenergy relations of leaves for 11 plant genera characterized by marked differences in leaf-mesophyll arrangements The research was based on the hypothesis that leaf-mesophyll arrangements influence spectral-energy relations of leaves and plant canopies Previous research had considered only the relation of light reflecshytance to leaf surface morphologies (28) and to isobilateral leaves (18)
Plants studied were corn (Zea mays L) banana (Musa acuminata Colla (M cavendishii Lamb) I begonia (Begonia C1tshy
bull Italic numbers in partnthfSfR refer to Literature Cited p 43
LEAF MESOPHYLLS OF TWENTY CROPS 5
cullata Willd (E sernperlo1ens Link amp Otto) eucalyptus (Eucalllptus camaldulensis Dehnh (E rostrata Schlecht) rose (Rosa val unknown) l hyacinth (Eichhornia crassipes (Mart) Solms sedum (Sedum spectabile Boreau) ficus (Ficus elastica
~ Roxb ex Hornem) oleander (Nerium oleander L Ligustrum (Lig1lstrnm l1lcidum Ait) and crinum (Crinum fimbriat1llum Baker)
Differences in leaf mesophylls among the 11 plant genera (Hi) were compared with (1) Spectrophotometrically measured reshyflectance and transmittance and calculated absorptance values of the leaves over the 500- to 2500-nanometer (nm) 4 wavelength interval (2) percent leaf-water contents (oven-dry weight basis) (3) leaf-thickness measurements and (4) optical and geometrical leaf parameters
Percent leaf-water contents of the 11 plant genera ranged from nO percent for isolateral ~ (palisade layers on both sides) eucalypshytus to 95 percent for succulent sedum and begonia leaves with storage cells on each side of a central chlorenchyma
Dorsiventral rose and compact corn leaves (no palisade cells) were thinnest (about 015 mm) and succulent sedum leaves were thickest (about 082 mm)
Spectral data for upper (adaxial) and lower (abaxial) leaf surfaces of all genera for 550- 800- 1000- 1450- 1650- 1950- ann 2200-nm wavelengths were appended Spectra of upper leaf surfaces of oleander corn hyacinth and eucalyptus were charted At the 1000-nm wavelength diffuse reflectance was highest for dorsiventral oleander and lowest for compact corn leaves transmittance was lowest for oleander and highest for corn leaves and absorptance for corn and oleander leaves was approximately 3 and 9 percent respectively rhe compact corn leaf with low light reflectance and high transmittance has fewer intercellular air spaces than the dorsi ventral oleander leaf
Because the interaction of plant genera with wavelength was small mean spectral measurements of 550- 800- 1000- 1450- 1650- 1950- and 2200-nm wavelengths were compared Lower leaf surfaces of dorsi ventral leaves had higher reflectance values than upper leaf surfaces indicating that the spongy parenchyma contribute more to light scattering than the palisade parenchyma
bull Both nanometer (nm) and micron (p) are used here to denote spectral wavelengths A nanometer is one thousandth of a micron and a micron is one thousandth of a millimeter
bull Botanical terms are definpd in the Glossary of Terms p 58
6 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of the leaf mesophyll This was substantiated by equal reflectance values of upper and lower surfaces of compact corn leaves
Thick leaves of oleander crinum fi~us sedum and Iigustrum had the lowest percent transmittarce Mean spectrophotometrishycally measured transmittance values for the above wavelengths were lower when light was passed from the top through the leaves than when light was passed through from the bottom The difference jn transmittance was caused by greater light diffusion by upper leaf surfaces since the spectrophotometer used irradishyates the specimen with direct light
Diffuse reflectance data were made absolute by correcting for decay of the magnesium-oxide standard on the spectrophotomshyeter and absorptance was calculated as 100 - [percent reshyflectance + percent transmittance] When data for wavelengths were averaged highest absorptance values of 606 582 591 and 583 percent were obtained for the thick dorsiventral ficus crinum ligustrum and oleander leaves respectively and lowest values of 404 and 390 percent were obtained for the thin comshypact corn and thin dorsiventral rose leaves respectively
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1450 nm) regions respectively At the 550-nm wavelengths reflectance was greater from the lower surface than from the upper surface of dorsiventral leaves indicating that the chloroplasts in the palisade cells absorbed light Lower and upper surface reflectances were the same for the compact corn leaves Considering upper leaf surfaces only thick succulent sedum and thick ficus leaves had the highest and lowest reflecshytance values of 20 and 8 percent respectively
Percent transmittance was lowest for ficus and highest for succulent begonia leaves Compact leaves of corn and succulent leaves of sedum and begonia with essentially a continuous mesoshyphyll arrangement had the loyrest light absorptance of approxishymately 70 percent Thick dorsiventral leaves of ficus oleander and ligustrum with multiseriide epidermal layers or multishypalisade layers had the highest light absorptance of 80 to 90 percent
At the 1000-nm wavelength reflectance values from upper and lower leaf surface measurements were essentially alike Comshypact corn leaves had the lowest reflectance (43 percent) and succulent sedum and dorsi ventral ficus oleander ligustrum and crinum leaves had the highest reflectance (53 percent) The 350
7 LEAF MESOPHYLLS OF TWENTY CROPS
percent transmithnce of oleander leaves was lowest and 545 percent for corn was highest The thin corn and rose leaves had the lowest absorptance values (2 to 3 percent) and the thick leaves of ligustrum ficus crinum sed urn and oleander had the highest values (8 to 11 percent)
Correlation coefficients were considered that accounted for at least 60 percent of the variation (r2 x 100) between leaf thickness and reflectance leaf thickness and absorptance leaf-water conshytent and refiectance and leaf-water content and absorptance Oleander eucalyptus and hyacinth leaves gave the highest coshyefficients among the plant genera studied In general co~ efficients were negative between water content and reflectance and between thickness and reflectance measurements and middotvith the main exception of eucalyptus coefficients were positive beshytween leaf-water content and absorptance and between thickness and absorptance calculations at 1450- 1650- 1950- and 2200shynm wavelengths
Experimental values of leaf reflectance and transmittance for the 11 genera were transformed into effective optical constants Such optical constants are useful in the prediction of reflectance phenomena associated with leaves either stacked in a spectroshyphotometer or arranged naturally in a plant canopy The index of refraction n was plotted against wavelength to obtain disshypersion curves The absorption coefficient k was shown to be equivalent to values determined previously for leaves from agrishycultural crops
Each of the 11 genera has been analyzed to obtain geometrical parameters that specify the amount of water and air in the leaf The water parameter is the thickness of liquid water necessary to produce the observed leaf absorption Observed and computed valuesmiddot of leaf-water thickness were obtained Agreement was good except for ligustrum crinum and sedum The air paramshyeter is the number of identical compact layers into which the equivalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance
A third parameter infinite reflectance is observed when leaves are piled sufficiently deep Infinite reflectance was tabulated at L65 p for all 11 genera Infinite reflectance was shown to be a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed
The literatUre dealing with the interaction of light with plant leaves and leaf mesophyl1 structure is reviewed in the technical
8 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
monograph by Gausman and others (15) and is not repeated here Attention is directed however to the research of Aboukhaled 6 who related the optical properties of leaves to their energy-balance photosynthesis and water-use efficiency
Materials and Methods Twenty plant genera were selected that are presently economshy
ically important or have the potential of becoming valuable in the Texas Lower Rio Grande Valley Pigweed was considered here as a crop rather than a weed because it is used by some farmers as a plow-under or green-manure crop The leaves of A
the selected genera varied in mesophyll arrangement thickness water content and other structural differences such as palisadeshylayer arrangement Leaf characteristics of the 20 crops and the families they represent are indicated in table 1 and typical photomicrographs of leaf transections are depicted in figure 1
All plants were field grown in the summer of 1970 except that lettuce and onions were purchased fresh at a local market soybeans and beans were grown in a greenhouse and wheat was grown during the 1969 season
Ten mature and healthy-appearing leaves were sampled from each of the 20 plant genera Immediately after excision leaves were wrapped in Saran or Glad-Wrap to minimize dehydration Leaves were wiped with a slightly dampened cloth to remove surface contaminants before spectrophotometric measurements The tubular onion leaf was split longitudinally and only oneshyhalf was measured
A Beckman Model DK-2A spectrophotometer equipped with a reflectance attachment was used to measure spectral diffuse
bull Aboukhaled A Optical properties of leaves in relation to their energyshybalance photosynthesis and water use efficiency (PhD thesis) University of Calif Library Davis 139 pp 1966
7 Trade names are used in this pUblication solely for the purpose of providing specific information Mention of a trade name does not constitute a guarantee or warranty of the product by the US Department of Agriculture or an endorsement by the Department over other products not mentioned
FIGURE I-Photomicrographs of leaf transections of 20 plant genera differing in leaf thickness mesophyll arrangement and other gross structural characteristics A avocado S bean C cantaloup D corniE cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
9 LEAF MESOPHYLLS OF TWENTY CROPS
FIGURE I-Continued
10 TECHNICAL BULLETIN 1middot165 US DEPT OF AGRICULTURE
FIGURE I-Continued
LEAF MESOPHYLLS OF TWENTY CROPS 11
reflectance and transmittance on adaxial (uppel) surfaces of single leaves over the 500- to 2500-nm wavelength interval Data have 1ieen corrected for decay of the magnesium-oxide standard (27) to give absolute radiometric data Absorptance was calculated from the absolute values as Percent absorptance = 100 - (percent reflectance + percent transmittance)
Measurements of leaf thickness and diffuse reflectance and transmittance and fixation of tissue were completed within 6 hours after leaves were harvested or obtained for each genus
Leaf thickness was measured with a linear-displacement transshyducer and digital voltmeter (17) Leaf area was determined with a planimeter except that area per leaf of corn sorghum and sugarcane was calculated by the method of Slickter Wearden and Pauli (29) and area per leaf of cotton was calculated by Tohnsons method (20) Percent leaf-water content was detershymined on an oven-dry weight basis by drying at 68deg C for 72 hours and cooling in a desiccator before final weighing Leaf thickness and water-content determinations were not made on wheat leaves
Tissue pieces taken near the center of leaves approximately one-half inch on either side of the midrib were fixed in formalinshyacetic acid-alcohol dehydrated with a tertiary butanol series embedded in paraffin stained with either the safranin-fast green or the safranin-fast green-orange G combinations (19) and transversally microtomed at 12- or 14- thickness The relatively thick transverse sections were used to accentuate intercellular spaces and thus enhance differences in mesophyll arrangeshyments among the crops Photomicrographs were obtained with a Zeiss Standard Universal Photomicroscope
Spectrophotometrically measured reflectance and transmittance and calculated absorptance of seven wavelengths (550 800 1000 14)0 1650 1950 and 2200 nm) were analyzed for variance (W) Duncans Multiple Range Test (7) was used to test differshyences among means of the seven wavelengths at the 5-percent probability level Standard deviation was calculated to compare the leaf reflectance transmittance and absorptance of the crops at the 550- and 1000-nm wavelengths Coefficients were calcushylated to evaluate the correlation of leaf thickness with leaf-water content Coefficients were also obtained for correlations of reshyflectance transmittance and absorptance with grams of water per cubic centimeter of leaf tissue leaf-water content on an ovenshydry weight basis and leaf thickness Correlation coefficients of plusmn 0775 were chosen as levels of significance because they acshy
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
~ID~O~O~--~i500~I~__~W~~--~aoo
500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
100 10
TRAHSiMTlAHCE
20
i i
401 ~ 1 ~
O ~
70
SO ~ REFLpoundCT~ 00
o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
N
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
p
500 1000 -~------- ~o
100
140
~50 460 170 -j80
90
0 RJOO
o---middotiir-~LiOo----2000L---2100
R
IDO~ 100
TRANSMfTTANCE
i ~
A8SORPT~CE
~~ 1 80 j
III REFLpoundCTANC( 90
Dshy~
aa
T
o
o~
Q
70 i 60~
I
~ ~u 201shy
bull Ill
o~
s
1000
IOO
wlllVflfJrtGTH fWI)
--oDIGTl1
~o
REFUclANCE
FIGURE 2-Continued
_~
2DOO
(HOO __--J
Z300
2gt00
10
120 1 30
1 ~ ~o ~ 60
10
bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
~
ACKNOWLEDGMENTS
We thank the following persons for the generous loan of specishymens for this study R H Arnett Purdue University W F Barr University of Idaho D E Bright Canadian National Collection of Insects Ottawa H R Burke Texas A amp 11 University G W Byers University of Kansas O L Cartwright Smithsoniari Inshystitution Washington DC J B Chapin Louisiana State Univershysity J A Chemsak University of California Berkeley P J Clausen University of Minnesota H Dybas Field Museum of Natural History Chicago M Emsley Academy of Natural Scishyences Philadelphia S Frommer University of California Rivershyside F F Hasbrouck Arizona State University K L Hays Auburn University M T James Washington State University J D Lattin Oregon State University R J Lavigne University of Wyoming J F Lawrence Museum of Comparative Zoology Harvard University H B Leech California Academy of Sciences G H Nelson Kansas City College of Osteopathy and Surgery L L Pechuman Cornell University P C Peterson University of Nebraska E P Rouse University of Arkansas R R Snelling Los Angeles County Museum R T Thompson British Museum (Natural History) P H Timberlake University of California Riverside C A Triplehorn Ohio State University J D Unzicker Illinois State Natural History Survey G E Wallace Carnegie Museum Pittsburgh R L Wenzel Field Museum of Natural History Chicago F G Werner University of Arizona and D A Young North Carolina State University
For identifying the many plants collected during this study we thank R H Hevly and J M Rominger Northern Arizona Unishyversity and W H Lewis Missouri Botanical Garden
The figures were draWll by Miss Deborah Learned and Rosser Garrisoll Northern Arizona University and the junior author
Rodolpho Hernandez Corzo Director General Direccion General de la Fauna Silvestre Mexico DF was especially cooperative in procuring permits for collecting in Mexico His help is gratefully acknowledged
Financial assistance was provided by the Entomology Research Division US Department of Agriculture under Grant 12-14-100shy9187 (33)
CONTENTS Ganus Sennius Bridwell ___________________________________________ Phylogenetic goups within Sennius _______________________________ _
Characters _________ ________________________________________ Host plants distribution and evohtion ________________________ Relationships of groups _______________________________________
Species introduced into the United States _________________________ _ Key to Sennius speciet ___________________________________________ _ Systematics of Sennius __________________________________________ _
S abbreviatus (Say) ________________________________________ S altmiddoticola (Sharp) new combination _________ ________________ S atripectus new species _____________________________________ S auricomus new species ____________________________________ _ S breveapicalis (Pic) new combination _______________________ _ S celatus (Sharp) ___________________________ _______________ S chalcodermus new species _________________________________ _ S cruentatus (Horn) ________________________________________ S discolor (Horn) ___________________________________________ S durangensis new species __________________________________ _ S ensiculus new species _____________________________________ _ S fallax (Boheman) new combination _________________________ S guttifer (Sharp) new combination __________________________ S inanis (Sharp) new combination ____________________________ S incultellus new species ____________________________________ _ S infractus new species ______________________________________ S instabilis (Sharp) new combination ________________________ _ S laminifer (Sharp) new combination _______________________ _ S leucostauros new species ___________________________________ S medialis (Sharp) new combination __________________________ S militaris (Sharp) new lombination ________________________ _ S morosus (Sharp) 1 new combination __________________________ Sobesulus (Sharp) new combination __________________________ S russeolus new species _____________________________________ _ S sintulans (Schaeffer) ______________________________________ S trinotaticollis (Pic) 1 new combination _______________________ _ S whitei new species _______________________________________ _
Literature cited _________________________________________________ _ Appendix ______________________________________________________ _
Synonymicallist of Senni1S species ____________________________ Phylogenetic groups of Sennius species ________________________ _ Sennius species and their host plants __________________________ Plants attacked by Sennius species _____________________________
Page
1 6 6 6 7
12 12 17 17 22 24 26 29 31 36 38 43 47 50 54 58 61 64 67 68 72 75 78 81 84 88 91 93 96 99
102 104 104 105 106 108
1lt ~ ~
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The Leaf Mesophylls of Twenty Crops Their Light Spectra
and Opti cal and Geomet~ical Parameters
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Technical Bulletin No 1465
~ ~ - I
Agricultural Research Service
UNITED STATES DEPARTMENT OF AGRICULTURE
In Cooperation With Texas Agricultural Experiment Station
Contents
Page Summary 1
Spectrophotometric measurements for seven
Spectrophotometric measurements at the
Correlations among spectrophotometric measurements and leaf-water content
Introduction 4 Materials and methods 8 Results and discussion 14 L~af water and thickness 14
selected wavelengths 20 Leaf spectra of four selected crops 22 Spectrophotometric measurements at the 550shy
nm wavelength 23
1OOO-nm wavelength 26
and thickness 27 Optical and geometrical leaf parameters 32
Literature cited 43 Appendix 46
Tables 46 Glossarv of terms 58
Issued March 1973
For sale by the Superintendent of Documents US Government Printing Office Washington DC 20402 - Price 50 cents domestic postpaid or
30 cents GPO Bookstore Stock Number 0100-02678
The Leaf Mesophylls of Twenty Crops Their Light Spectra and
Optical and Geometrical Parameters1
H W GAUSMAN pl1nt physiologist W A ALLEN research physicist C L WIEGAND soil scientist D E ESCOBAR biological laboratory techshyncian R R RODRIGUEZ phy~ical science technician and A J RICHARDSON physicist Southern Region AgriC1tltural Research Service United States Department 0 Agricultlre
Summary Leaf mesophylls among 20 agricultural crops are compared
with (1) Spectrophotometrically measured percent reflectances and transmittances and calculated absorptances of the leaves over the 500- to 2500-nanometer (nm) wavelength interval (2) percent leaf-water contents (3) leaf thickness measureshyments and (4) opthal and geometrical leaf parameters Data are given as averages of 10 leaves (replications) for each crop The crops are Avocado bean cantaloup corn cotton lettuce okra onion orange peach pepper pigweed pumpkin sorghum soybean sugarcane sunflower tomato watermelon and wheat
Thick succulent lettuce leaves had the highest water content (970 percent) and dorsiventral avocado orange and peach and compact sugarcane leaves had the lowest water contents (range 606 to 724 percent)
Soybean peach pumpkin and pigweed leaves were thinnest (range 0140 to 0170 mm) and sunflower cantaloup lettuce and onion leaves were thickest (range 0407 to 0978 mm)
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1350 nm) spectral regions Data for lettuce were omitted because the leaves sampled middotere immature
1 The work was supported in part by the National Aeronautics and Space Administration und~r NASA Contract No R-09-038-002 Current Code No 160-75-01-07-10
2 The authors acknowledge the histological and technical assistance of Guadalupe Cardona Marcia Schupp and Ron Bowen Thaks are extended to the Amul Company Development Center Weslaco Tex for 3upplying the bean and soybean plants
1
2 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
The mean reflectance of the crop leaves at the 550-nm waveshylength was 13 3 plusmn 28 percent (one standard deviation) The majority of crops fell within the 133 pound 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane leaves (162 to 186 percent)
At the 550-nm wavelength transmittances of orange tomato and avocado (19 to 55 percent) and okra soybean onion (148 to 188 percent) fell outside the 98 plusmn 42 percent range
The mean absorptance for the crops at 550-nm wavelength was 769 plusmn 58 percent Thirteen crops fell within the 769 plusmn 58 percent range Sugarcane onion bean and peppel leaves with low absorptance (692 to 706 percent) and peach tomato avoshycado and orange leaves with high absorptance (829 to 879 pershycent) fell outside the 769 plusmn 58 percent range The leaves with high absorptance had well-differentiated dorsiventral mesophylls with many chloroplasts in their palisade cells Leaves with low absorptance had poorly differentiated mesophylls-less distincshytion between palisade and spongy parenchyma cells
The 1OOO-nm wavelength was llsed to evaluate the influence of leaf-mesophyll arrangement on near-infrared (750 to 1350 nm) light reflectance The mean reflectance of the crop leaves at the IOOO-nm wavelength was 480 plusmn 39 percent The reflectance of onion (38) percent) and orange and bean (556 and 562 pershycent respectively) fell outside this range However only oneshyhalf of the tubular onion leaf (split longitudinally) was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn sugarcane and soybean leaves had the lowest reflectances (451 to 460 percent) and dOlsiventral bean orange and pepper leaves with very porous mesophyll had the highest reflectances (510 to 562 percent)
At the IOOO-nm wavelength the mean transmittance of all crop leaves was 479 plusmn 37 percent All crops fell within this rang-e except orange (389 percent) and bean (420 percent) and soybean pigweed and onion (522 to 540 percent)
The mean absorptance of all crop leaves at the 1000-nm waveshylength was 40 plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 pershycent) fell outside the 40 plusmn 17 percent range
Correlation coefficients equal to or larger than plusmn 0775 are conshysidered that accounted for at least 60 percent of the variation (0775 z x 100) between comparisons Negative coefficients exshyceeding - 0775 were obtained for correlations between light reshy
LEAF MESOPHYLLS OF TWENTY CROPS 3
flectance and percent leaf-water content for sugarcane at 1450- 1650- and 2200-nm for corn at 550- and 1450-nm for pigweed at 1450-nm and for tomato at 1450- and 2200-nm wavelengths Soybean had positive coefficients exceeding 0775 for the correlashytion between reflectance and leaf thickness at the 550- 800- and 1OOO-nm wavelengths and a negative coefficient that exshyceeded -077f5 for the correlation between transmittance and leaf thickness at the 1000-nm wavelength Soybean leaves also had large negative coefficients for the correlation between reshyflectance and leaf thickness at the 1450- 1950- and 2200-nm wavelengths and for the correlation between transmittance and leaf thickness at the 1450- 1650- 1950- and 2200-nm waveshylengths Peach pigweed tomato bean and onion crops also had high negative coefficients for t~e correlation between transmitshytance and leaf thickness at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths High positive coefficients were obtained for the correlation between leaf thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
The grams of water per cubic centimeter of leaf tissue were calculated for each crop leaf used except wheat There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue For transmittance coefficients exceeded -0775 only for okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and brams of water per cubic centimeter of leaf tissue gave high posishytive coefficients for okra leaves at 1450 1650 and 2200 nm
Experimental values of leaf reflectance and transmittance for the 20 crops have been transformed into effective optical conshystants Such optical constants are useful in the prediction of reshyflectance phenomena associated with leaves either stacked in a spectrophotometer or arranged naturally in a plant canopy The index of refraction n is plotted against wavelength to obtain disshypersion curves The values for the absorption coefficient k that are tabulated for the various crops are equivalent to values detershymined previously for leaves from agricultural crops
The dispersion curves of most of the crop leaves were reshymarkably similar in shape and in relatively close confidence bands Onion pigweed and lettuce were exceptions but only one-half of the tubular onion leaves (split longitudinally) was used lettuce leaves were immature and veins of pigweed leaves are surrounded by large cubical parenchymatous cells
4 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Sixteen of the 20 crops were analyzed to determine the thickshyness of water necessary to produce the observed leaf absorption and the number of identical compact layers into which the equivshyalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance Sugarcane corn sorghum and wheat leaves were not included because laborashytory determinations of thickness and water content were not made on entire leaves There was no statistically significant difshyference between observed and computed values for leaf water for 10 of the crops Pumpkin avocado okra tomato cantaloup and lettuce showed differences but they were not highly significant
The limiting value of reflectance from leaves piled sufficiently deep is termed infinite reflectance This parameter is a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed Infinite reflectance has been tabulated at 165 p for the 20 crops
Introduction To interpret remote-sensing data from aircraft and spacecraft
thE reflectance produced by features on the ~arths surface must be understood (33)3 The specific problem in agriculture is interpretation of reflectance produced by vegetation usuaIIy supershyimposed on a soil background Plant leaves yield most of the signal measured by remote sensors in aircraft a1 rl spacecraft Therefore they are of prime interest in characterizing vegetashytion and their interaction with electromagnetic radiation must be understood
The purpose of research reported here was to relate the leaf mesophyll structure of 20 important agricultural plant genera to their light spectra and to optical and geometrical parameters This report is a sequel to a technical monograph by Gausman and others (15) which presented research results on the spectralshyenergy relations of leaves for 11 plant genera characterized by marked differences in leaf-mesophyll arrangements The research was based on the hypothesis that leaf-mesophyll arrangements influence spectral-energy relations of leaves and plant canopies Previous research had considered only the relation of light reflecshytance to leaf surface morphologies (28) and to isobilateral leaves (18)
Plants studied were corn (Zea mays L) banana (Musa acuminata Colla (M cavendishii Lamb) I begonia (Begonia C1tshy
bull Italic numbers in partnthfSfR refer to Literature Cited p 43
LEAF MESOPHYLLS OF TWENTY CROPS 5
cullata Willd (E sernperlo1ens Link amp Otto) eucalyptus (Eucalllptus camaldulensis Dehnh (E rostrata Schlecht) rose (Rosa val unknown) l hyacinth (Eichhornia crassipes (Mart) Solms sedum (Sedum spectabile Boreau) ficus (Ficus elastica
~ Roxb ex Hornem) oleander (Nerium oleander L Ligustrum (Lig1lstrnm l1lcidum Ait) and crinum (Crinum fimbriat1llum Baker)
Differences in leaf mesophylls among the 11 plant genera (Hi) were compared with (1) Spectrophotometrically measured reshyflectance and transmittance and calculated absorptance values of the leaves over the 500- to 2500-nanometer (nm) 4 wavelength interval (2) percent leaf-water contents (oven-dry weight basis) (3) leaf-thickness measurements and (4) optical and geometrical leaf parameters
Percent leaf-water contents of the 11 plant genera ranged from nO percent for isolateral ~ (palisade layers on both sides) eucalypshytus to 95 percent for succulent sedum and begonia leaves with storage cells on each side of a central chlorenchyma
Dorsiventral rose and compact corn leaves (no palisade cells) were thinnest (about 015 mm) and succulent sedum leaves were thickest (about 082 mm)
Spectral data for upper (adaxial) and lower (abaxial) leaf surfaces of all genera for 550- 800- 1000- 1450- 1650- 1950- ann 2200-nm wavelengths were appended Spectra of upper leaf surfaces of oleander corn hyacinth and eucalyptus were charted At the 1000-nm wavelength diffuse reflectance was highest for dorsiventral oleander and lowest for compact corn leaves transmittance was lowest for oleander and highest for corn leaves and absorptance for corn and oleander leaves was approximately 3 and 9 percent respectively rhe compact corn leaf with low light reflectance and high transmittance has fewer intercellular air spaces than the dorsi ventral oleander leaf
Because the interaction of plant genera with wavelength was small mean spectral measurements of 550- 800- 1000- 1450- 1650- 1950- and 2200-nm wavelengths were compared Lower leaf surfaces of dorsi ventral leaves had higher reflectance values than upper leaf surfaces indicating that the spongy parenchyma contribute more to light scattering than the palisade parenchyma
bull Both nanometer (nm) and micron (p) are used here to denote spectral wavelengths A nanometer is one thousandth of a micron and a micron is one thousandth of a millimeter
bull Botanical terms are definpd in the Glossary of Terms p 58
6 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of the leaf mesophyll This was substantiated by equal reflectance values of upper and lower surfaces of compact corn leaves
Thick leaves of oleander crinum fi~us sedum and Iigustrum had the lowest percent transmittarce Mean spectrophotometrishycally measured transmittance values for the above wavelengths were lower when light was passed from the top through the leaves than when light was passed through from the bottom The difference jn transmittance was caused by greater light diffusion by upper leaf surfaces since the spectrophotometer used irradishyates the specimen with direct light
Diffuse reflectance data were made absolute by correcting for decay of the magnesium-oxide standard on the spectrophotomshyeter and absorptance was calculated as 100 - [percent reshyflectance + percent transmittance] When data for wavelengths were averaged highest absorptance values of 606 582 591 and 583 percent were obtained for the thick dorsiventral ficus crinum ligustrum and oleander leaves respectively and lowest values of 404 and 390 percent were obtained for the thin comshypact corn and thin dorsiventral rose leaves respectively
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1450 nm) regions respectively At the 550-nm wavelengths reflectance was greater from the lower surface than from the upper surface of dorsiventral leaves indicating that the chloroplasts in the palisade cells absorbed light Lower and upper surface reflectances were the same for the compact corn leaves Considering upper leaf surfaces only thick succulent sedum and thick ficus leaves had the highest and lowest reflecshytance values of 20 and 8 percent respectively
Percent transmittance was lowest for ficus and highest for succulent begonia leaves Compact leaves of corn and succulent leaves of sedum and begonia with essentially a continuous mesoshyphyll arrangement had the loyrest light absorptance of approxishymately 70 percent Thick dorsiventral leaves of ficus oleander and ligustrum with multiseriide epidermal layers or multishypalisade layers had the highest light absorptance of 80 to 90 percent
At the 1000-nm wavelength reflectance values from upper and lower leaf surface measurements were essentially alike Comshypact corn leaves had the lowest reflectance (43 percent) and succulent sedum and dorsi ventral ficus oleander ligustrum and crinum leaves had the highest reflectance (53 percent) The 350
7 LEAF MESOPHYLLS OF TWENTY CROPS
percent transmithnce of oleander leaves was lowest and 545 percent for corn was highest The thin corn and rose leaves had the lowest absorptance values (2 to 3 percent) and the thick leaves of ligustrum ficus crinum sed urn and oleander had the highest values (8 to 11 percent)
Correlation coefficients were considered that accounted for at least 60 percent of the variation (r2 x 100) between leaf thickness and reflectance leaf thickness and absorptance leaf-water conshytent and refiectance and leaf-water content and absorptance Oleander eucalyptus and hyacinth leaves gave the highest coshyefficients among the plant genera studied In general co~ efficients were negative between water content and reflectance and between thickness and reflectance measurements and middotvith the main exception of eucalyptus coefficients were positive beshytween leaf-water content and absorptance and between thickness and absorptance calculations at 1450- 1650- 1950- and 2200shynm wavelengths
Experimental values of leaf reflectance and transmittance for the 11 genera were transformed into effective optical constants Such optical constants are useful in the prediction of reflectance phenomena associated with leaves either stacked in a spectroshyphotometer or arranged naturally in a plant canopy The index of refraction n was plotted against wavelength to obtain disshypersion curves The absorption coefficient k was shown to be equivalent to values determined previously for leaves from agrishycultural crops
Each of the 11 genera has been analyzed to obtain geometrical parameters that specify the amount of water and air in the leaf The water parameter is the thickness of liquid water necessary to produce the observed leaf absorption Observed and computed valuesmiddot of leaf-water thickness were obtained Agreement was good except for ligustrum crinum and sedum The air paramshyeter is the number of identical compact layers into which the equivalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance
A third parameter infinite reflectance is observed when leaves are piled sufficiently deep Infinite reflectance was tabulated at L65 p for all 11 genera Infinite reflectance was shown to be a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed
The literatUre dealing with the interaction of light with plant leaves and leaf mesophyl1 structure is reviewed in the technical
8 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
monograph by Gausman and others (15) and is not repeated here Attention is directed however to the research of Aboukhaled 6 who related the optical properties of leaves to their energy-balance photosynthesis and water-use efficiency
Materials and Methods Twenty plant genera were selected that are presently economshy
ically important or have the potential of becoming valuable in the Texas Lower Rio Grande Valley Pigweed was considered here as a crop rather than a weed because it is used by some farmers as a plow-under or green-manure crop The leaves of A
the selected genera varied in mesophyll arrangement thickness water content and other structural differences such as palisadeshylayer arrangement Leaf characteristics of the 20 crops and the families they represent are indicated in table 1 and typical photomicrographs of leaf transections are depicted in figure 1
All plants were field grown in the summer of 1970 except that lettuce and onions were purchased fresh at a local market soybeans and beans were grown in a greenhouse and wheat was grown during the 1969 season
Ten mature and healthy-appearing leaves were sampled from each of the 20 plant genera Immediately after excision leaves were wrapped in Saran or Glad-Wrap to minimize dehydration Leaves were wiped with a slightly dampened cloth to remove surface contaminants before spectrophotometric measurements The tubular onion leaf was split longitudinally and only oneshyhalf was measured
A Beckman Model DK-2A spectrophotometer equipped with a reflectance attachment was used to measure spectral diffuse
bull Aboukhaled A Optical properties of leaves in relation to their energyshybalance photosynthesis and water use efficiency (PhD thesis) University of Calif Library Davis 139 pp 1966
7 Trade names are used in this pUblication solely for the purpose of providing specific information Mention of a trade name does not constitute a guarantee or warranty of the product by the US Department of Agriculture or an endorsement by the Department over other products not mentioned
FIGURE I-Photomicrographs of leaf transections of 20 plant genera differing in leaf thickness mesophyll arrangement and other gross structural characteristics A avocado S bean C cantaloup D corniE cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
9 LEAF MESOPHYLLS OF TWENTY CROPS
FIGURE I-Continued
10 TECHNICAL BULLETIN 1middot165 US DEPT OF AGRICULTURE
FIGURE I-Continued
LEAF MESOPHYLLS OF TWENTY CROPS 11
reflectance and transmittance on adaxial (uppel) surfaces of single leaves over the 500- to 2500-nm wavelength interval Data have 1ieen corrected for decay of the magnesium-oxide standard (27) to give absolute radiometric data Absorptance was calculated from the absolute values as Percent absorptance = 100 - (percent reflectance + percent transmittance)
Measurements of leaf thickness and diffuse reflectance and transmittance and fixation of tissue were completed within 6 hours after leaves were harvested or obtained for each genus
Leaf thickness was measured with a linear-displacement transshyducer and digital voltmeter (17) Leaf area was determined with a planimeter except that area per leaf of corn sorghum and sugarcane was calculated by the method of Slickter Wearden and Pauli (29) and area per leaf of cotton was calculated by Tohnsons method (20) Percent leaf-water content was detershymined on an oven-dry weight basis by drying at 68deg C for 72 hours and cooling in a desiccator before final weighing Leaf thickness and water-content determinations were not made on wheat leaves
Tissue pieces taken near the center of leaves approximately one-half inch on either side of the midrib were fixed in formalinshyacetic acid-alcohol dehydrated with a tertiary butanol series embedded in paraffin stained with either the safranin-fast green or the safranin-fast green-orange G combinations (19) and transversally microtomed at 12- or 14- thickness The relatively thick transverse sections were used to accentuate intercellular spaces and thus enhance differences in mesophyll arrangeshyments among the crops Photomicrographs were obtained with a Zeiss Standard Universal Photomicroscope
Spectrophotometrically measured reflectance and transmittance and calculated absorptance of seven wavelengths (550 800 1000 14)0 1650 1950 and 2200 nm) were analyzed for variance (W) Duncans Multiple Range Test (7) was used to test differshyences among means of the seven wavelengths at the 5-percent probability level Standard deviation was calculated to compare the leaf reflectance transmittance and absorptance of the crops at the 550- and 1000-nm wavelengths Coefficients were calcushylated to evaluate the correlation of leaf thickness with leaf-water content Coefficients were also obtained for correlations of reshyflectance transmittance and absorptance with grams of water per cubic centimeter of leaf tissue leaf-water content on an ovenshydry weight basis and leaf thickness Correlation coefficients of plusmn 0775 were chosen as levels of significance because they acshy
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
~ID~O~O~--~i500~I~__~W~~--~aoo
500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
100 10
TRAHSiMTlAHCE
20
i i
401 ~ 1 ~
O ~
70
SO ~ REFLpoundCT~ 00
o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
N
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
p
500 1000 -~------- ~o
100
140
~50 460 170 -j80
90
0 RJOO
o---middotiir-~LiOo----2000L---2100
R
IDO~ 100
TRANSMfTTANCE
i ~
A8SORPT~CE
~~ 1 80 j
III REFLpoundCTANC( 90
Dshy~
aa
T
o
o~
Q
70 i 60~
I
~ ~u 201shy
bull Ill
o~
s
1000
IOO
wlllVflfJrtGTH fWI)
--oDIGTl1
~o
REFUclANCE
FIGURE 2-Continued
_~
2DOO
(HOO __--J
Z300
2gt00
10
120 1 30
1 ~ ~o ~ 60
10
bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
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bull ~
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44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
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LEAF MESOPHYLLS OF TWENTY CROPS 45
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~
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1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
CONTENTS Ganus Sennius Bridwell ___________________________________________ Phylogenetic goups within Sennius _______________________________ _
Characters _________ ________________________________________ Host plants distribution and evohtion ________________________ Relationships of groups _______________________________________
Species introduced into the United States _________________________ _ Key to Sennius speciet ___________________________________________ _ Systematics of Sennius __________________________________________ _
S abbreviatus (Say) ________________________________________ S altmiddoticola (Sharp) new combination _________ ________________ S atripectus new species _____________________________________ S auricomus new species ____________________________________ _ S breveapicalis (Pic) new combination _______________________ _ S celatus (Sharp) ___________________________ _______________ S chalcodermus new species _________________________________ _ S cruentatus (Horn) ________________________________________ S discolor (Horn) ___________________________________________ S durangensis new species __________________________________ _ S ensiculus new species _____________________________________ _ S fallax (Boheman) new combination _________________________ S guttifer (Sharp) new combination __________________________ S inanis (Sharp) new combination ____________________________ S incultellus new species ____________________________________ _ S infractus new species ______________________________________ S instabilis (Sharp) new combination ________________________ _ S laminifer (Sharp) new combination _______________________ _ S leucostauros new species ___________________________________ S medialis (Sharp) new combination __________________________ S militaris (Sharp) new lombination ________________________ _ S morosus (Sharp) 1 new combination __________________________ Sobesulus (Sharp) new combination __________________________ S russeolus new species _____________________________________ _ S sintulans (Schaeffer) ______________________________________ S trinotaticollis (Pic) 1 new combination _______________________ _ S whitei new species _______________________________________ _
Literature cited _________________________________________________ _ Appendix ______________________________________________________ _
Synonymicallist of Senni1S species ____________________________ Phylogenetic groups of Sennius species ________________________ _ Sennius species and their host plants __________________________ Plants attacked by Sennius species _____________________________
Page
1 6 6 6 7
12 12 17 17 22 24 26 29 31 36 38 43 47 50 54 58 61 64 67 68 72 75 78 81 84 88 91 93 96 99
102 104 104 105 106 108
1lt ~ ~
-tf ) L 0 7
The Leaf Mesophylls of Twenty Crops Their Light Spectra
and Opti cal and Geomet~ical Parameters
~ ~ ~ 0 amp-I p-I
ll1 O
~ ~
~ ~
(lt) r-shyt
r
0gt1
c- CL lt
- ~((7J r ~ 1-4
- ~ ~~ p shy
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( ~
Technical Bulletin No 1465
~ ~ - I
Agricultural Research Service
UNITED STATES DEPARTMENT OF AGRICULTURE
In Cooperation With Texas Agricultural Experiment Station
Contents
Page Summary 1
Spectrophotometric measurements for seven
Spectrophotometric measurements at the
Correlations among spectrophotometric measurements and leaf-water content
Introduction 4 Materials and methods 8 Results and discussion 14 L~af water and thickness 14
selected wavelengths 20 Leaf spectra of four selected crops 22 Spectrophotometric measurements at the 550shy
nm wavelength 23
1OOO-nm wavelength 26
and thickness 27 Optical and geometrical leaf parameters 32
Literature cited 43 Appendix 46
Tables 46 Glossarv of terms 58
Issued March 1973
For sale by the Superintendent of Documents US Government Printing Office Washington DC 20402 - Price 50 cents domestic postpaid or
30 cents GPO Bookstore Stock Number 0100-02678
The Leaf Mesophylls of Twenty Crops Their Light Spectra and
Optical and Geometrical Parameters1
H W GAUSMAN pl1nt physiologist W A ALLEN research physicist C L WIEGAND soil scientist D E ESCOBAR biological laboratory techshyncian R R RODRIGUEZ phy~ical science technician and A J RICHARDSON physicist Southern Region AgriC1tltural Research Service United States Department 0 Agricultlre
Summary Leaf mesophylls among 20 agricultural crops are compared
with (1) Spectrophotometrically measured percent reflectances and transmittances and calculated absorptances of the leaves over the 500- to 2500-nanometer (nm) wavelength interval (2) percent leaf-water contents (3) leaf thickness measureshyments and (4) opthal and geometrical leaf parameters Data are given as averages of 10 leaves (replications) for each crop The crops are Avocado bean cantaloup corn cotton lettuce okra onion orange peach pepper pigweed pumpkin sorghum soybean sugarcane sunflower tomato watermelon and wheat
Thick succulent lettuce leaves had the highest water content (970 percent) and dorsiventral avocado orange and peach and compact sugarcane leaves had the lowest water contents (range 606 to 724 percent)
Soybean peach pumpkin and pigweed leaves were thinnest (range 0140 to 0170 mm) and sunflower cantaloup lettuce and onion leaves were thickest (range 0407 to 0978 mm)
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1350 nm) spectral regions Data for lettuce were omitted because the leaves sampled middotere immature
1 The work was supported in part by the National Aeronautics and Space Administration und~r NASA Contract No R-09-038-002 Current Code No 160-75-01-07-10
2 The authors acknowledge the histological and technical assistance of Guadalupe Cardona Marcia Schupp and Ron Bowen Thaks are extended to the Amul Company Development Center Weslaco Tex for 3upplying the bean and soybean plants
1
2 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
The mean reflectance of the crop leaves at the 550-nm waveshylength was 13 3 plusmn 28 percent (one standard deviation) The majority of crops fell within the 133 pound 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane leaves (162 to 186 percent)
At the 550-nm wavelength transmittances of orange tomato and avocado (19 to 55 percent) and okra soybean onion (148 to 188 percent) fell outside the 98 plusmn 42 percent range
The mean absorptance for the crops at 550-nm wavelength was 769 plusmn 58 percent Thirteen crops fell within the 769 plusmn 58 percent range Sugarcane onion bean and peppel leaves with low absorptance (692 to 706 percent) and peach tomato avoshycado and orange leaves with high absorptance (829 to 879 pershycent) fell outside the 769 plusmn 58 percent range The leaves with high absorptance had well-differentiated dorsiventral mesophylls with many chloroplasts in their palisade cells Leaves with low absorptance had poorly differentiated mesophylls-less distincshytion between palisade and spongy parenchyma cells
The 1OOO-nm wavelength was llsed to evaluate the influence of leaf-mesophyll arrangement on near-infrared (750 to 1350 nm) light reflectance The mean reflectance of the crop leaves at the IOOO-nm wavelength was 480 plusmn 39 percent The reflectance of onion (38) percent) and orange and bean (556 and 562 pershycent respectively) fell outside this range However only oneshyhalf of the tubular onion leaf (split longitudinally) was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn sugarcane and soybean leaves had the lowest reflectances (451 to 460 percent) and dOlsiventral bean orange and pepper leaves with very porous mesophyll had the highest reflectances (510 to 562 percent)
At the IOOO-nm wavelength the mean transmittance of all crop leaves was 479 plusmn 37 percent All crops fell within this rang-e except orange (389 percent) and bean (420 percent) and soybean pigweed and onion (522 to 540 percent)
The mean absorptance of all crop leaves at the 1000-nm waveshylength was 40 plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 pershycent) fell outside the 40 plusmn 17 percent range
Correlation coefficients equal to or larger than plusmn 0775 are conshysidered that accounted for at least 60 percent of the variation (0775 z x 100) between comparisons Negative coefficients exshyceeding - 0775 were obtained for correlations between light reshy
LEAF MESOPHYLLS OF TWENTY CROPS 3
flectance and percent leaf-water content for sugarcane at 1450- 1650- and 2200-nm for corn at 550- and 1450-nm for pigweed at 1450-nm and for tomato at 1450- and 2200-nm wavelengths Soybean had positive coefficients exceeding 0775 for the correlashytion between reflectance and leaf thickness at the 550- 800- and 1OOO-nm wavelengths and a negative coefficient that exshyceeded -077f5 for the correlation between transmittance and leaf thickness at the 1000-nm wavelength Soybean leaves also had large negative coefficients for the correlation between reshyflectance and leaf thickness at the 1450- 1950- and 2200-nm wavelengths and for the correlation between transmittance and leaf thickness at the 1450- 1650- 1950- and 2200-nm waveshylengths Peach pigweed tomato bean and onion crops also had high negative coefficients for t~e correlation between transmitshytance and leaf thickness at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths High positive coefficients were obtained for the correlation between leaf thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
The grams of water per cubic centimeter of leaf tissue were calculated for each crop leaf used except wheat There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue For transmittance coefficients exceeded -0775 only for okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and brams of water per cubic centimeter of leaf tissue gave high posishytive coefficients for okra leaves at 1450 1650 and 2200 nm
Experimental values of leaf reflectance and transmittance for the 20 crops have been transformed into effective optical conshystants Such optical constants are useful in the prediction of reshyflectance phenomena associated with leaves either stacked in a spectrophotometer or arranged naturally in a plant canopy The index of refraction n is plotted against wavelength to obtain disshypersion curves The values for the absorption coefficient k that are tabulated for the various crops are equivalent to values detershymined previously for leaves from agricultural crops
The dispersion curves of most of the crop leaves were reshymarkably similar in shape and in relatively close confidence bands Onion pigweed and lettuce were exceptions but only one-half of the tubular onion leaves (split longitudinally) was used lettuce leaves were immature and veins of pigweed leaves are surrounded by large cubical parenchymatous cells
4 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Sixteen of the 20 crops were analyzed to determine the thickshyness of water necessary to produce the observed leaf absorption and the number of identical compact layers into which the equivshyalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance Sugarcane corn sorghum and wheat leaves were not included because laborashytory determinations of thickness and water content were not made on entire leaves There was no statistically significant difshyference between observed and computed values for leaf water for 10 of the crops Pumpkin avocado okra tomato cantaloup and lettuce showed differences but they were not highly significant
The limiting value of reflectance from leaves piled sufficiently deep is termed infinite reflectance This parameter is a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed Infinite reflectance has been tabulated at 165 p for the 20 crops
Introduction To interpret remote-sensing data from aircraft and spacecraft
thE reflectance produced by features on the ~arths surface must be understood (33)3 The specific problem in agriculture is interpretation of reflectance produced by vegetation usuaIIy supershyimposed on a soil background Plant leaves yield most of the signal measured by remote sensors in aircraft a1 rl spacecraft Therefore they are of prime interest in characterizing vegetashytion and their interaction with electromagnetic radiation must be understood
The purpose of research reported here was to relate the leaf mesophyll structure of 20 important agricultural plant genera to their light spectra and to optical and geometrical parameters This report is a sequel to a technical monograph by Gausman and others (15) which presented research results on the spectralshyenergy relations of leaves for 11 plant genera characterized by marked differences in leaf-mesophyll arrangements The research was based on the hypothesis that leaf-mesophyll arrangements influence spectral-energy relations of leaves and plant canopies Previous research had considered only the relation of light reflecshytance to leaf surface morphologies (28) and to isobilateral leaves (18)
Plants studied were corn (Zea mays L) banana (Musa acuminata Colla (M cavendishii Lamb) I begonia (Begonia C1tshy
bull Italic numbers in partnthfSfR refer to Literature Cited p 43
LEAF MESOPHYLLS OF TWENTY CROPS 5
cullata Willd (E sernperlo1ens Link amp Otto) eucalyptus (Eucalllptus camaldulensis Dehnh (E rostrata Schlecht) rose (Rosa val unknown) l hyacinth (Eichhornia crassipes (Mart) Solms sedum (Sedum spectabile Boreau) ficus (Ficus elastica
~ Roxb ex Hornem) oleander (Nerium oleander L Ligustrum (Lig1lstrnm l1lcidum Ait) and crinum (Crinum fimbriat1llum Baker)
Differences in leaf mesophylls among the 11 plant genera (Hi) were compared with (1) Spectrophotometrically measured reshyflectance and transmittance and calculated absorptance values of the leaves over the 500- to 2500-nanometer (nm) 4 wavelength interval (2) percent leaf-water contents (oven-dry weight basis) (3) leaf-thickness measurements and (4) optical and geometrical leaf parameters
Percent leaf-water contents of the 11 plant genera ranged from nO percent for isolateral ~ (palisade layers on both sides) eucalypshytus to 95 percent for succulent sedum and begonia leaves with storage cells on each side of a central chlorenchyma
Dorsiventral rose and compact corn leaves (no palisade cells) were thinnest (about 015 mm) and succulent sedum leaves were thickest (about 082 mm)
Spectral data for upper (adaxial) and lower (abaxial) leaf surfaces of all genera for 550- 800- 1000- 1450- 1650- 1950- ann 2200-nm wavelengths were appended Spectra of upper leaf surfaces of oleander corn hyacinth and eucalyptus were charted At the 1000-nm wavelength diffuse reflectance was highest for dorsiventral oleander and lowest for compact corn leaves transmittance was lowest for oleander and highest for corn leaves and absorptance for corn and oleander leaves was approximately 3 and 9 percent respectively rhe compact corn leaf with low light reflectance and high transmittance has fewer intercellular air spaces than the dorsi ventral oleander leaf
Because the interaction of plant genera with wavelength was small mean spectral measurements of 550- 800- 1000- 1450- 1650- 1950- and 2200-nm wavelengths were compared Lower leaf surfaces of dorsi ventral leaves had higher reflectance values than upper leaf surfaces indicating that the spongy parenchyma contribute more to light scattering than the palisade parenchyma
bull Both nanometer (nm) and micron (p) are used here to denote spectral wavelengths A nanometer is one thousandth of a micron and a micron is one thousandth of a millimeter
bull Botanical terms are definpd in the Glossary of Terms p 58
6 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of the leaf mesophyll This was substantiated by equal reflectance values of upper and lower surfaces of compact corn leaves
Thick leaves of oleander crinum fi~us sedum and Iigustrum had the lowest percent transmittarce Mean spectrophotometrishycally measured transmittance values for the above wavelengths were lower when light was passed from the top through the leaves than when light was passed through from the bottom The difference jn transmittance was caused by greater light diffusion by upper leaf surfaces since the spectrophotometer used irradishyates the specimen with direct light
Diffuse reflectance data were made absolute by correcting for decay of the magnesium-oxide standard on the spectrophotomshyeter and absorptance was calculated as 100 - [percent reshyflectance + percent transmittance] When data for wavelengths were averaged highest absorptance values of 606 582 591 and 583 percent were obtained for the thick dorsiventral ficus crinum ligustrum and oleander leaves respectively and lowest values of 404 and 390 percent were obtained for the thin comshypact corn and thin dorsiventral rose leaves respectively
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1450 nm) regions respectively At the 550-nm wavelengths reflectance was greater from the lower surface than from the upper surface of dorsiventral leaves indicating that the chloroplasts in the palisade cells absorbed light Lower and upper surface reflectances were the same for the compact corn leaves Considering upper leaf surfaces only thick succulent sedum and thick ficus leaves had the highest and lowest reflecshytance values of 20 and 8 percent respectively
Percent transmittance was lowest for ficus and highest for succulent begonia leaves Compact leaves of corn and succulent leaves of sedum and begonia with essentially a continuous mesoshyphyll arrangement had the loyrest light absorptance of approxishymately 70 percent Thick dorsiventral leaves of ficus oleander and ligustrum with multiseriide epidermal layers or multishypalisade layers had the highest light absorptance of 80 to 90 percent
At the 1000-nm wavelength reflectance values from upper and lower leaf surface measurements were essentially alike Comshypact corn leaves had the lowest reflectance (43 percent) and succulent sedum and dorsi ventral ficus oleander ligustrum and crinum leaves had the highest reflectance (53 percent) The 350
7 LEAF MESOPHYLLS OF TWENTY CROPS
percent transmithnce of oleander leaves was lowest and 545 percent for corn was highest The thin corn and rose leaves had the lowest absorptance values (2 to 3 percent) and the thick leaves of ligustrum ficus crinum sed urn and oleander had the highest values (8 to 11 percent)
Correlation coefficients were considered that accounted for at least 60 percent of the variation (r2 x 100) between leaf thickness and reflectance leaf thickness and absorptance leaf-water conshytent and refiectance and leaf-water content and absorptance Oleander eucalyptus and hyacinth leaves gave the highest coshyefficients among the plant genera studied In general co~ efficients were negative between water content and reflectance and between thickness and reflectance measurements and middotvith the main exception of eucalyptus coefficients were positive beshytween leaf-water content and absorptance and between thickness and absorptance calculations at 1450- 1650- 1950- and 2200shynm wavelengths
Experimental values of leaf reflectance and transmittance for the 11 genera were transformed into effective optical constants Such optical constants are useful in the prediction of reflectance phenomena associated with leaves either stacked in a spectroshyphotometer or arranged naturally in a plant canopy The index of refraction n was plotted against wavelength to obtain disshypersion curves The absorption coefficient k was shown to be equivalent to values determined previously for leaves from agrishycultural crops
Each of the 11 genera has been analyzed to obtain geometrical parameters that specify the amount of water and air in the leaf The water parameter is the thickness of liquid water necessary to produce the observed leaf absorption Observed and computed valuesmiddot of leaf-water thickness were obtained Agreement was good except for ligustrum crinum and sedum The air paramshyeter is the number of identical compact layers into which the equivalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance
A third parameter infinite reflectance is observed when leaves are piled sufficiently deep Infinite reflectance was tabulated at L65 p for all 11 genera Infinite reflectance was shown to be a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed
The literatUre dealing with the interaction of light with plant leaves and leaf mesophyl1 structure is reviewed in the technical
8 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
monograph by Gausman and others (15) and is not repeated here Attention is directed however to the research of Aboukhaled 6 who related the optical properties of leaves to their energy-balance photosynthesis and water-use efficiency
Materials and Methods Twenty plant genera were selected that are presently economshy
ically important or have the potential of becoming valuable in the Texas Lower Rio Grande Valley Pigweed was considered here as a crop rather than a weed because it is used by some farmers as a plow-under or green-manure crop The leaves of A
the selected genera varied in mesophyll arrangement thickness water content and other structural differences such as palisadeshylayer arrangement Leaf characteristics of the 20 crops and the families they represent are indicated in table 1 and typical photomicrographs of leaf transections are depicted in figure 1
All plants were field grown in the summer of 1970 except that lettuce and onions were purchased fresh at a local market soybeans and beans were grown in a greenhouse and wheat was grown during the 1969 season
Ten mature and healthy-appearing leaves were sampled from each of the 20 plant genera Immediately after excision leaves were wrapped in Saran or Glad-Wrap to minimize dehydration Leaves were wiped with a slightly dampened cloth to remove surface contaminants before spectrophotometric measurements The tubular onion leaf was split longitudinally and only oneshyhalf was measured
A Beckman Model DK-2A spectrophotometer equipped with a reflectance attachment was used to measure spectral diffuse
bull Aboukhaled A Optical properties of leaves in relation to their energyshybalance photosynthesis and water use efficiency (PhD thesis) University of Calif Library Davis 139 pp 1966
7 Trade names are used in this pUblication solely for the purpose of providing specific information Mention of a trade name does not constitute a guarantee or warranty of the product by the US Department of Agriculture or an endorsement by the Department over other products not mentioned
FIGURE I-Photomicrographs of leaf transections of 20 plant genera differing in leaf thickness mesophyll arrangement and other gross structural characteristics A avocado S bean C cantaloup D corniE cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
9 LEAF MESOPHYLLS OF TWENTY CROPS
FIGURE I-Continued
10 TECHNICAL BULLETIN 1middot165 US DEPT OF AGRICULTURE
FIGURE I-Continued
LEAF MESOPHYLLS OF TWENTY CROPS 11
reflectance and transmittance on adaxial (uppel) surfaces of single leaves over the 500- to 2500-nm wavelength interval Data have 1ieen corrected for decay of the magnesium-oxide standard (27) to give absolute radiometric data Absorptance was calculated from the absolute values as Percent absorptance = 100 - (percent reflectance + percent transmittance)
Measurements of leaf thickness and diffuse reflectance and transmittance and fixation of tissue were completed within 6 hours after leaves were harvested or obtained for each genus
Leaf thickness was measured with a linear-displacement transshyducer and digital voltmeter (17) Leaf area was determined with a planimeter except that area per leaf of corn sorghum and sugarcane was calculated by the method of Slickter Wearden and Pauli (29) and area per leaf of cotton was calculated by Tohnsons method (20) Percent leaf-water content was detershymined on an oven-dry weight basis by drying at 68deg C for 72 hours and cooling in a desiccator before final weighing Leaf thickness and water-content determinations were not made on wheat leaves
Tissue pieces taken near the center of leaves approximately one-half inch on either side of the midrib were fixed in formalinshyacetic acid-alcohol dehydrated with a tertiary butanol series embedded in paraffin stained with either the safranin-fast green or the safranin-fast green-orange G combinations (19) and transversally microtomed at 12- or 14- thickness The relatively thick transverse sections were used to accentuate intercellular spaces and thus enhance differences in mesophyll arrangeshyments among the crops Photomicrographs were obtained with a Zeiss Standard Universal Photomicroscope
Spectrophotometrically measured reflectance and transmittance and calculated absorptance of seven wavelengths (550 800 1000 14)0 1650 1950 and 2200 nm) were analyzed for variance (W) Duncans Multiple Range Test (7) was used to test differshyences among means of the seven wavelengths at the 5-percent probability level Standard deviation was calculated to compare the leaf reflectance transmittance and absorptance of the crops at the 550- and 1000-nm wavelengths Coefficients were calcushylated to evaluate the correlation of leaf thickness with leaf-water content Coefficients were also obtained for correlations of reshyflectance transmittance and absorptance with grams of water per cubic centimeter of leaf tissue leaf-water content on an ovenshydry weight basis and leaf thickness Correlation coefficients of plusmn 0775 were chosen as levels of significance because they acshy
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
~ID~O~O~--~i500~I~__~W~~--~aoo
500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
100 10
TRAHSiMTlAHCE
20
i i
401 ~ 1 ~
O ~
70
SO ~ REFLpoundCT~ 00
o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
N
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
p
500 1000 -~------- ~o
100
140
~50 460 170 -j80
90
0 RJOO
o---middotiir-~LiOo----2000L---2100
R
IDO~ 100
TRANSMfTTANCE
i ~
A8SORPT~CE
~~ 1 80 j
III REFLpoundCTANC( 90
Dshy~
aa
T
o
o~
Q
70 i 60~
I
~ ~u 201shy
bull Ill
o~
s
1000
IOO
wlllVflfJrtGTH fWI)
--oDIGTl1
~o
REFUclANCE
FIGURE 2-Continued
_~
2DOO
(HOO __--J
Z300
2gt00
10
120 1 30
1 ~ ~o ~ 60
10
bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
1lt ~ ~
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The Leaf Mesophylls of Twenty Crops Their Light Spectra
and Opti cal and Geomet~ical Parameters
~ ~ ~ 0 amp-I p-I
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Technical Bulletin No 1465
~ ~ - I
Agricultural Research Service
UNITED STATES DEPARTMENT OF AGRICULTURE
In Cooperation With Texas Agricultural Experiment Station
Contents
Page Summary 1
Spectrophotometric measurements for seven
Spectrophotometric measurements at the
Correlations among spectrophotometric measurements and leaf-water content
Introduction 4 Materials and methods 8 Results and discussion 14 L~af water and thickness 14
selected wavelengths 20 Leaf spectra of four selected crops 22 Spectrophotometric measurements at the 550shy
nm wavelength 23
1OOO-nm wavelength 26
and thickness 27 Optical and geometrical leaf parameters 32
Literature cited 43 Appendix 46
Tables 46 Glossarv of terms 58
Issued March 1973
For sale by the Superintendent of Documents US Government Printing Office Washington DC 20402 - Price 50 cents domestic postpaid or
30 cents GPO Bookstore Stock Number 0100-02678
The Leaf Mesophylls of Twenty Crops Their Light Spectra and
Optical and Geometrical Parameters1
H W GAUSMAN pl1nt physiologist W A ALLEN research physicist C L WIEGAND soil scientist D E ESCOBAR biological laboratory techshyncian R R RODRIGUEZ phy~ical science technician and A J RICHARDSON physicist Southern Region AgriC1tltural Research Service United States Department 0 Agricultlre
Summary Leaf mesophylls among 20 agricultural crops are compared
with (1) Spectrophotometrically measured percent reflectances and transmittances and calculated absorptances of the leaves over the 500- to 2500-nanometer (nm) wavelength interval (2) percent leaf-water contents (3) leaf thickness measureshyments and (4) opthal and geometrical leaf parameters Data are given as averages of 10 leaves (replications) for each crop The crops are Avocado bean cantaloup corn cotton lettuce okra onion orange peach pepper pigweed pumpkin sorghum soybean sugarcane sunflower tomato watermelon and wheat
Thick succulent lettuce leaves had the highest water content (970 percent) and dorsiventral avocado orange and peach and compact sugarcane leaves had the lowest water contents (range 606 to 724 percent)
Soybean peach pumpkin and pigweed leaves were thinnest (range 0140 to 0170 mm) and sunflower cantaloup lettuce and onion leaves were thickest (range 0407 to 0978 mm)
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1350 nm) spectral regions Data for lettuce were omitted because the leaves sampled middotere immature
1 The work was supported in part by the National Aeronautics and Space Administration und~r NASA Contract No R-09-038-002 Current Code No 160-75-01-07-10
2 The authors acknowledge the histological and technical assistance of Guadalupe Cardona Marcia Schupp and Ron Bowen Thaks are extended to the Amul Company Development Center Weslaco Tex for 3upplying the bean and soybean plants
1
2 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
The mean reflectance of the crop leaves at the 550-nm waveshylength was 13 3 plusmn 28 percent (one standard deviation) The majority of crops fell within the 133 pound 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane leaves (162 to 186 percent)
At the 550-nm wavelength transmittances of orange tomato and avocado (19 to 55 percent) and okra soybean onion (148 to 188 percent) fell outside the 98 plusmn 42 percent range
The mean absorptance for the crops at 550-nm wavelength was 769 plusmn 58 percent Thirteen crops fell within the 769 plusmn 58 percent range Sugarcane onion bean and peppel leaves with low absorptance (692 to 706 percent) and peach tomato avoshycado and orange leaves with high absorptance (829 to 879 pershycent) fell outside the 769 plusmn 58 percent range The leaves with high absorptance had well-differentiated dorsiventral mesophylls with many chloroplasts in their palisade cells Leaves with low absorptance had poorly differentiated mesophylls-less distincshytion between palisade and spongy parenchyma cells
The 1OOO-nm wavelength was llsed to evaluate the influence of leaf-mesophyll arrangement on near-infrared (750 to 1350 nm) light reflectance The mean reflectance of the crop leaves at the IOOO-nm wavelength was 480 plusmn 39 percent The reflectance of onion (38) percent) and orange and bean (556 and 562 pershycent respectively) fell outside this range However only oneshyhalf of the tubular onion leaf (split longitudinally) was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn sugarcane and soybean leaves had the lowest reflectances (451 to 460 percent) and dOlsiventral bean orange and pepper leaves with very porous mesophyll had the highest reflectances (510 to 562 percent)
At the IOOO-nm wavelength the mean transmittance of all crop leaves was 479 plusmn 37 percent All crops fell within this rang-e except orange (389 percent) and bean (420 percent) and soybean pigweed and onion (522 to 540 percent)
The mean absorptance of all crop leaves at the 1000-nm waveshylength was 40 plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 pershycent) fell outside the 40 plusmn 17 percent range
Correlation coefficients equal to or larger than plusmn 0775 are conshysidered that accounted for at least 60 percent of the variation (0775 z x 100) between comparisons Negative coefficients exshyceeding - 0775 were obtained for correlations between light reshy
LEAF MESOPHYLLS OF TWENTY CROPS 3
flectance and percent leaf-water content for sugarcane at 1450- 1650- and 2200-nm for corn at 550- and 1450-nm for pigweed at 1450-nm and for tomato at 1450- and 2200-nm wavelengths Soybean had positive coefficients exceeding 0775 for the correlashytion between reflectance and leaf thickness at the 550- 800- and 1OOO-nm wavelengths and a negative coefficient that exshyceeded -077f5 for the correlation between transmittance and leaf thickness at the 1000-nm wavelength Soybean leaves also had large negative coefficients for the correlation between reshyflectance and leaf thickness at the 1450- 1950- and 2200-nm wavelengths and for the correlation between transmittance and leaf thickness at the 1450- 1650- 1950- and 2200-nm waveshylengths Peach pigweed tomato bean and onion crops also had high negative coefficients for t~e correlation between transmitshytance and leaf thickness at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths High positive coefficients were obtained for the correlation between leaf thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
The grams of water per cubic centimeter of leaf tissue were calculated for each crop leaf used except wheat There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue For transmittance coefficients exceeded -0775 only for okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and brams of water per cubic centimeter of leaf tissue gave high posishytive coefficients for okra leaves at 1450 1650 and 2200 nm
Experimental values of leaf reflectance and transmittance for the 20 crops have been transformed into effective optical conshystants Such optical constants are useful in the prediction of reshyflectance phenomena associated with leaves either stacked in a spectrophotometer or arranged naturally in a plant canopy The index of refraction n is plotted against wavelength to obtain disshypersion curves The values for the absorption coefficient k that are tabulated for the various crops are equivalent to values detershymined previously for leaves from agricultural crops
The dispersion curves of most of the crop leaves were reshymarkably similar in shape and in relatively close confidence bands Onion pigweed and lettuce were exceptions but only one-half of the tubular onion leaves (split longitudinally) was used lettuce leaves were immature and veins of pigweed leaves are surrounded by large cubical parenchymatous cells
4 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Sixteen of the 20 crops were analyzed to determine the thickshyness of water necessary to produce the observed leaf absorption and the number of identical compact layers into which the equivshyalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance Sugarcane corn sorghum and wheat leaves were not included because laborashytory determinations of thickness and water content were not made on entire leaves There was no statistically significant difshyference between observed and computed values for leaf water for 10 of the crops Pumpkin avocado okra tomato cantaloup and lettuce showed differences but they were not highly significant
The limiting value of reflectance from leaves piled sufficiently deep is termed infinite reflectance This parameter is a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed Infinite reflectance has been tabulated at 165 p for the 20 crops
Introduction To interpret remote-sensing data from aircraft and spacecraft
thE reflectance produced by features on the ~arths surface must be understood (33)3 The specific problem in agriculture is interpretation of reflectance produced by vegetation usuaIIy supershyimposed on a soil background Plant leaves yield most of the signal measured by remote sensors in aircraft a1 rl spacecraft Therefore they are of prime interest in characterizing vegetashytion and their interaction with electromagnetic radiation must be understood
The purpose of research reported here was to relate the leaf mesophyll structure of 20 important agricultural plant genera to their light spectra and to optical and geometrical parameters This report is a sequel to a technical monograph by Gausman and others (15) which presented research results on the spectralshyenergy relations of leaves for 11 plant genera characterized by marked differences in leaf-mesophyll arrangements The research was based on the hypothesis that leaf-mesophyll arrangements influence spectral-energy relations of leaves and plant canopies Previous research had considered only the relation of light reflecshytance to leaf surface morphologies (28) and to isobilateral leaves (18)
Plants studied were corn (Zea mays L) banana (Musa acuminata Colla (M cavendishii Lamb) I begonia (Begonia C1tshy
bull Italic numbers in partnthfSfR refer to Literature Cited p 43
LEAF MESOPHYLLS OF TWENTY CROPS 5
cullata Willd (E sernperlo1ens Link amp Otto) eucalyptus (Eucalllptus camaldulensis Dehnh (E rostrata Schlecht) rose (Rosa val unknown) l hyacinth (Eichhornia crassipes (Mart) Solms sedum (Sedum spectabile Boreau) ficus (Ficus elastica
~ Roxb ex Hornem) oleander (Nerium oleander L Ligustrum (Lig1lstrnm l1lcidum Ait) and crinum (Crinum fimbriat1llum Baker)
Differences in leaf mesophylls among the 11 plant genera (Hi) were compared with (1) Spectrophotometrically measured reshyflectance and transmittance and calculated absorptance values of the leaves over the 500- to 2500-nanometer (nm) 4 wavelength interval (2) percent leaf-water contents (oven-dry weight basis) (3) leaf-thickness measurements and (4) optical and geometrical leaf parameters
Percent leaf-water contents of the 11 plant genera ranged from nO percent for isolateral ~ (palisade layers on both sides) eucalypshytus to 95 percent for succulent sedum and begonia leaves with storage cells on each side of a central chlorenchyma
Dorsiventral rose and compact corn leaves (no palisade cells) were thinnest (about 015 mm) and succulent sedum leaves were thickest (about 082 mm)
Spectral data for upper (adaxial) and lower (abaxial) leaf surfaces of all genera for 550- 800- 1000- 1450- 1650- 1950- ann 2200-nm wavelengths were appended Spectra of upper leaf surfaces of oleander corn hyacinth and eucalyptus were charted At the 1000-nm wavelength diffuse reflectance was highest for dorsiventral oleander and lowest for compact corn leaves transmittance was lowest for oleander and highest for corn leaves and absorptance for corn and oleander leaves was approximately 3 and 9 percent respectively rhe compact corn leaf with low light reflectance and high transmittance has fewer intercellular air spaces than the dorsi ventral oleander leaf
Because the interaction of plant genera with wavelength was small mean spectral measurements of 550- 800- 1000- 1450- 1650- 1950- and 2200-nm wavelengths were compared Lower leaf surfaces of dorsi ventral leaves had higher reflectance values than upper leaf surfaces indicating that the spongy parenchyma contribute more to light scattering than the palisade parenchyma
bull Both nanometer (nm) and micron (p) are used here to denote spectral wavelengths A nanometer is one thousandth of a micron and a micron is one thousandth of a millimeter
bull Botanical terms are definpd in the Glossary of Terms p 58
6 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of the leaf mesophyll This was substantiated by equal reflectance values of upper and lower surfaces of compact corn leaves
Thick leaves of oleander crinum fi~us sedum and Iigustrum had the lowest percent transmittarce Mean spectrophotometrishycally measured transmittance values for the above wavelengths were lower when light was passed from the top through the leaves than when light was passed through from the bottom The difference jn transmittance was caused by greater light diffusion by upper leaf surfaces since the spectrophotometer used irradishyates the specimen with direct light
Diffuse reflectance data were made absolute by correcting for decay of the magnesium-oxide standard on the spectrophotomshyeter and absorptance was calculated as 100 - [percent reshyflectance + percent transmittance] When data for wavelengths were averaged highest absorptance values of 606 582 591 and 583 percent were obtained for the thick dorsiventral ficus crinum ligustrum and oleander leaves respectively and lowest values of 404 and 390 percent were obtained for the thin comshypact corn and thin dorsiventral rose leaves respectively
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1450 nm) regions respectively At the 550-nm wavelengths reflectance was greater from the lower surface than from the upper surface of dorsiventral leaves indicating that the chloroplasts in the palisade cells absorbed light Lower and upper surface reflectances were the same for the compact corn leaves Considering upper leaf surfaces only thick succulent sedum and thick ficus leaves had the highest and lowest reflecshytance values of 20 and 8 percent respectively
Percent transmittance was lowest for ficus and highest for succulent begonia leaves Compact leaves of corn and succulent leaves of sedum and begonia with essentially a continuous mesoshyphyll arrangement had the loyrest light absorptance of approxishymately 70 percent Thick dorsiventral leaves of ficus oleander and ligustrum with multiseriide epidermal layers or multishypalisade layers had the highest light absorptance of 80 to 90 percent
At the 1000-nm wavelength reflectance values from upper and lower leaf surface measurements were essentially alike Comshypact corn leaves had the lowest reflectance (43 percent) and succulent sedum and dorsi ventral ficus oleander ligustrum and crinum leaves had the highest reflectance (53 percent) The 350
7 LEAF MESOPHYLLS OF TWENTY CROPS
percent transmithnce of oleander leaves was lowest and 545 percent for corn was highest The thin corn and rose leaves had the lowest absorptance values (2 to 3 percent) and the thick leaves of ligustrum ficus crinum sed urn and oleander had the highest values (8 to 11 percent)
Correlation coefficients were considered that accounted for at least 60 percent of the variation (r2 x 100) between leaf thickness and reflectance leaf thickness and absorptance leaf-water conshytent and refiectance and leaf-water content and absorptance Oleander eucalyptus and hyacinth leaves gave the highest coshyefficients among the plant genera studied In general co~ efficients were negative between water content and reflectance and between thickness and reflectance measurements and middotvith the main exception of eucalyptus coefficients were positive beshytween leaf-water content and absorptance and between thickness and absorptance calculations at 1450- 1650- 1950- and 2200shynm wavelengths
Experimental values of leaf reflectance and transmittance for the 11 genera were transformed into effective optical constants Such optical constants are useful in the prediction of reflectance phenomena associated with leaves either stacked in a spectroshyphotometer or arranged naturally in a plant canopy The index of refraction n was plotted against wavelength to obtain disshypersion curves The absorption coefficient k was shown to be equivalent to values determined previously for leaves from agrishycultural crops
Each of the 11 genera has been analyzed to obtain geometrical parameters that specify the amount of water and air in the leaf The water parameter is the thickness of liquid water necessary to produce the observed leaf absorption Observed and computed valuesmiddot of leaf-water thickness were obtained Agreement was good except for ligustrum crinum and sedum The air paramshyeter is the number of identical compact layers into which the equivalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance
A third parameter infinite reflectance is observed when leaves are piled sufficiently deep Infinite reflectance was tabulated at L65 p for all 11 genera Infinite reflectance was shown to be a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed
The literatUre dealing with the interaction of light with plant leaves and leaf mesophyl1 structure is reviewed in the technical
8 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
monograph by Gausman and others (15) and is not repeated here Attention is directed however to the research of Aboukhaled 6 who related the optical properties of leaves to their energy-balance photosynthesis and water-use efficiency
Materials and Methods Twenty plant genera were selected that are presently economshy
ically important or have the potential of becoming valuable in the Texas Lower Rio Grande Valley Pigweed was considered here as a crop rather than a weed because it is used by some farmers as a plow-under or green-manure crop The leaves of A
the selected genera varied in mesophyll arrangement thickness water content and other structural differences such as palisadeshylayer arrangement Leaf characteristics of the 20 crops and the families they represent are indicated in table 1 and typical photomicrographs of leaf transections are depicted in figure 1
All plants were field grown in the summer of 1970 except that lettuce and onions were purchased fresh at a local market soybeans and beans were grown in a greenhouse and wheat was grown during the 1969 season
Ten mature and healthy-appearing leaves were sampled from each of the 20 plant genera Immediately after excision leaves were wrapped in Saran or Glad-Wrap to minimize dehydration Leaves were wiped with a slightly dampened cloth to remove surface contaminants before spectrophotometric measurements The tubular onion leaf was split longitudinally and only oneshyhalf was measured
A Beckman Model DK-2A spectrophotometer equipped with a reflectance attachment was used to measure spectral diffuse
bull Aboukhaled A Optical properties of leaves in relation to their energyshybalance photosynthesis and water use efficiency (PhD thesis) University of Calif Library Davis 139 pp 1966
7 Trade names are used in this pUblication solely for the purpose of providing specific information Mention of a trade name does not constitute a guarantee or warranty of the product by the US Department of Agriculture or an endorsement by the Department over other products not mentioned
FIGURE I-Photomicrographs of leaf transections of 20 plant genera differing in leaf thickness mesophyll arrangement and other gross structural characteristics A avocado S bean C cantaloup D corniE cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
9 LEAF MESOPHYLLS OF TWENTY CROPS
FIGURE I-Continued
10 TECHNICAL BULLETIN 1middot165 US DEPT OF AGRICULTURE
FIGURE I-Continued
LEAF MESOPHYLLS OF TWENTY CROPS 11
reflectance and transmittance on adaxial (uppel) surfaces of single leaves over the 500- to 2500-nm wavelength interval Data have 1ieen corrected for decay of the magnesium-oxide standard (27) to give absolute radiometric data Absorptance was calculated from the absolute values as Percent absorptance = 100 - (percent reflectance + percent transmittance)
Measurements of leaf thickness and diffuse reflectance and transmittance and fixation of tissue were completed within 6 hours after leaves were harvested or obtained for each genus
Leaf thickness was measured with a linear-displacement transshyducer and digital voltmeter (17) Leaf area was determined with a planimeter except that area per leaf of corn sorghum and sugarcane was calculated by the method of Slickter Wearden and Pauli (29) and area per leaf of cotton was calculated by Tohnsons method (20) Percent leaf-water content was detershymined on an oven-dry weight basis by drying at 68deg C for 72 hours and cooling in a desiccator before final weighing Leaf thickness and water-content determinations were not made on wheat leaves
Tissue pieces taken near the center of leaves approximately one-half inch on either side of the midrib were fixed in formalinshyacetic acid-alcohol dehydrated with a tertiary butanol series embedded in paraffin stained with either the safranin-fast green or the safranin-fast green-orange G combinations (19) and transversally microtomed at 12- or 14- thickness The relatively thick transverse sections were used to accentuate intercellular spaces and thus enhance differences in mesophyll arrangeshyments among the crops Photomicrographs were obtained with a Zeiss Standard Universal Photomicroscope
Spectrophotometrically measured reflectance and transmittance and calculated absorptance of seven wavelengths (550 800 1000 14)0 1650 1950 and 2200 nm) were analyzed for variance (W) Duncans Multiple Range Test (7) was used to test differshyences among means of the seven wavelengths at the 5-percent probability level Standard deviation was calculated to compare the leaf reflectance transmittance and absorptance of the crops at the 550- and 1000-nm wavelengths Coefficients were calcushylated to evaluate the correlation of leaf thickness with leaf-water content Coefficients were also obtained for correlations of reshyflectance transmittance and absorptance with grams of water per cubic centimeter of leaf tissue leaf-water content on an ovenshydry weight basis and leaf thickness Correlation coefficients of plusmn 0775 were chosen as levels of significance because they acshy
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
~ID~O~O~--~i500~I~__~W~~--~aoo
500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
100 10
TRAHSiMTlAHCE
20
i i
401 ~ 1 ~
O ~
70
SO ~ REFLpoundCT~ 00
o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
N
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
p
500 1000 -~------- ~o
100
140
~50 460 170 -j80
90
0 RJOO
o---middotiir-~LiOo----2000L---2100
R
IDO~ 100
TRANSMfTTANCE
i ~
A8SORPT~CE
~~ 1 80 j
III REFLpoundCTANC( 90
Dshy~
aa
T
o
o~
Q
70 i 60~
I
~ ~u 201shy
bull Ill
o~
s
1000
IOO
wlllVflfJrtGTH fWI)
--oDIGTl1
~o
REFUclANCE
FIGURE 2-Continued
_~
2DOO
(HOO __--J
Z300
2gt00
10
120 1 30
1 ~ ~o ~ 60
10
bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
Contents
Page Summary 1
Spectrophotometric measurements for seven
Spectrophotometric measurements at the
Correlations among spectrophotometric measurements and leaf-water content
Introduction 4 Materials and methods 8 Results and discussion 14 L~af water and thickness 14
selected wavelengths 20 Leaf spectra of four selected crops 22 Spectrophotometric measurements at the 550shy
nm wavelength 23
1OOO-nm wavelength 26
and thickness 27 Optical and geometrical leaf parameters 32
Literature cited 43 Appendix 46
Tables 46 Glossarv of terms 58
Issued March 1973
For sale by the Superintendent of Documents US Government Printing Office Washington DC 20402 - Price 50 cents domestic postpaid or
30 cents GPO Bookstore Stock Number 0100-02678
The Leaf Mesophylls of Twenty Crops Their Light Spectra and
Optical and Geometrical Parameters1
H W GAUSMAN pl1nt physiologist W A ALLEN research physicist C L WIEGAND soil scientist D E ESCOBAR biological laboratory techshyncian R R RODRIGUEZ phy~ical science technician and A J RICHARDSON physicist Southern Region AgriC1tltural Research Service United States Department 0 Agricultlre
Summary Leaf mesophylls among 20 agricultural crops are compared
with (1) Spectrophotometrically measured percent reflectances and transmittances and calculated absorptances of the leaves over the 500- to 2500-nanometer (nm) wavelength interval (2) percent leaf-water contents (3) leaf thickness measureshyments and (4) opthal and geometrical leaf parameters Data are given as averages of 10 leaves (replications) for each crop The crops are Avocado bean cantaloup corn cotton lettuce okra onion orange peach pepper pigweed pumpkin sorghum soybean sugarcane sunflower tomato watermelon and wheat
Thick succulent lettuce leaves had the highest water content (970 percent) and dorsiventral avocado orange and peach and compact sugarcane leaves had the lowest water contents (range 606 to 724 percent)
Soybean peach pumpkin and pigweed leaves were thinnest (range 0140 to 0170 mm) and sunflower cantaloup lettuce and onion leaves were thickest (range 0407 to 0978 mm)
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1350 nm) spectral regions Data for lettuce were omitted because the leaves sampled middotere immature
1 The work was supported in part by the National Aeronautics and Space Administration und~r NASA Contract No R-09-038-002 Current Code No 160-75-01-07-10
2 The authors acknowledge the histological and technical assistance of Guadalupe Cardona Marcia Schupp and Ron Bowen Thaks are extended to the Amul Company Development Center Weslaco Tex for 3upplying the bean and soybean plants
1
2 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
The mean reflectance of the crop leaves at the 550-nm waveshylength was 13 3 plusmn 28 percent (one standard deviation) The majority of crops fell within the 133 pound 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane leaves (162 to 186 percent)
At the 550-nm wavelength transmittances of orange tomato and avocado (19 to 55 percent) and okra soybean onion (148 to 188 percent) fell outside the 98 plusmn 42 percent range
The mean absorptance for the crops at 550-nm wavelength was 769 plusmn 58 percent Thirteen crops fell within the 769 plusmn 58 percent range Sugarcane onion bean and peppel leaves with low absorptance (692 to 706 percent) and peach tomato avoshycado and orange leaves with high absorptance (829 to 879 pershycent) fell outside the 769 plusmn 58 percent range The leaves with high absorptance had well-differentiated dorsiventral mesophylls with many chloroplasts in their palisade cells Leaves with low absorptance had poorly differentiated mesophylls-less distincshytion between palisade and spongy parenchyma cells
The 1OOO-nm wavelength was llsed to evaluate the influence of leaf-mesophyll arrangement on near-infrared (750 to 1350 nm) light reflectance The mean reflectance of the crop leaves at the IOOO-nm wavelength was 480 plusmn 39 percent The reflectance of onion (38) percent) and orange and bean (556 and 562 pershycent respectively) fell outside this range However only oneshyhalf of the tubular onion leaf (split longitudinally) was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn sugarcane and soybean leaves had the lowest reflectances (451 to 460 percent) and dOlsiventral bean orange and pepper leaves with very porous mesophyll had the highest reflectances (510 to 562 percent)
At the IOOO-nm wavelength the mean transmittance of all crop leaves was 479 plusmn 37 percent All crops fell within this rang-e except orange (389 percent) and bean (420 percent) and soybean pigweed and onion (522 to 540 percent)
The mean absorptance of all crop leaves at the 1000-nm waveshylength was 40 plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 pershycent) fell outside the 40 plusmn 17 percent range
Correlation coefficients equal to or larger than plusmn 0775 are conshysidered that accounted for at least 60 percent of the variation (0775 z x 100) between comparisons Negative coefficients exshyceeding - 0775 were obtained for correlations between light reshy
LEAF MESOPHYLLS OF TWENTY CROPS 3
flectance and percent leaf-water content for sugarcane at 1450- 1650- and 2200-nm for corn at 550- and 1450-nm for pigweed at 1450-nm and for tomato at 1450- and 2200-nm wavelengths Soybean had positive coefficients exceeding 0775 for the correlashytion between reflectance and leaf thickness at the 550- 800- and 1OOO-nm wavelengths and a negative coefficient that exshyceeded -077f5 for the correlation between transmittance and leaf thickness at the 1000-nm wavelength Soybean leaves also had large negative coefficients for the correlation between reshyflectance and leaf thickness at the 1450- 1950- and 2200-nm wavelengths and for the correlation between transmittance and leaf thickness at the 1450- 1650- 1950- and 2200-nm waveshylengths Peach pigweed tomato bean and onion crops also had high negative coefficients for t~e correlation between transmitshytance and leaf thickness at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths High positive coefficients were obtained for the correlation between leaf thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
The grams of water per cubic centimeter of leaf tissue were calculated for each crop leaf used except wheat There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue For transmittance coefficients exceeded -0775 only for okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and brams of water per cubic centimeter of leaf tissue gave high posishytive coefficients for okra leaves at 1450 1650 and 2200 nm
Experimental values of leaf reflectance and transmittance for the 20 crops have been transformed into effective optical conshystants Such optical constants are useful in the prediction of reshyflectance phenomena associated with leaves either stacked in a spectrophotometer or arranged naturally in a plant canopy The index of refraction n is plotted against wavelength to obtain disshypersion curves The values for the absorption coefficient k that are tabulated for the various crops are equivalent to values detershymined previously for leaves from agricultural crops
The dispersion curves of most of the crop leaves were reshymarkably similar in shape and in relatively close confidence bands Onion pigweed and lettuce were exceptions but only one-half of the tubular onion leaves (split longitudinally) was used lettuce leaves were immature and veins of pigweed leaves are surrounded by large cubical parenchymatous cells
4 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Sixteen of the 20 crops were analyzed to determine the thickshyness of water necessary to produce the observed leaf absorption and the number of identical compact layers into which the equivshyalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance Sugarcane corn sorghum and wheat leaves were not included because laborashytory determinations of thickness and water content were not made on entire leaves There was no statistically significant difshyference between observed and computed values for leaf water for 10 of the crops Pumpkin avocado okra tomato cantaloup and lettuce showed differences but they were not highly significant
The limiting value of reflectance from leaves piled sufficiently deep is termed infinite reflectance This parameter is a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed Infinite reflectance has been tabulated at 165 p for the 20 crops
Introduction To interpret remote-sensing data from aircraft and spacecraft
thE reflectance produced by features on the ~arths surface must be understood (33)3 The specific problem in agriculture is interpretation of reflectance produced by vegetation usuaIIy supershyimposed on a soil background Plant leaves yield most of the signal measured by remote sensors in aircraft a1 rl spacecraft Therefore they are of prime interest in characterizing vegetashytion and their interaction with electromagnetic radiation must be understood
The purpose of research reported here was to relate the leaf mesophyll structure of 20 important agricultural plant genera to their light spectra and to optical and geometrical parameters This report is a sequel to a technical monograph by Gausman and others (15) which presented research results on the spectralshyenergy relations of leaves for 11 plant genera characterized by marked differences in leaf-mesophyll arrangements The research was based on the hypothesis that leaf-mesophyll arrangements influence spectral-energy relations of leaves and plant canopies Previous research had considered only the relation of light reflecshytance to leaf surface morphologies (28) and to isobilateral leaves (18)
Plants studied were corn (Zea mays L) banana (Musa acuminata Colla (M cavendishii Lamb) I begonia (Begonia C1tshy
bull Italic numbers in partnthfSfR refer to Literature Cited p 43
LEAF MESOPHYLLS OF TWENTY CROPS 5
cullata Willd (E sernperlo1ens Link amp Otto) eucalyptus (Eucalllptus camaldulensis Dehnh (E rostrata Schlecht) rose (Rosa val unknown) l hyacinth (Eichhornia crassipes (Mart) Solms sedum (Sedum spectabile Boreau) ficus (Ficus elastica
~ Roxb ex Hornem) oleander (Nerium oleander L Ligustrum (Lig1lstrnm l1lcidum Ait) and crinum (Crinum fimbriat1llum Baker)
Differences in leaf mesophylls among the 11 plant genera (Hi) were compared with (1) Spectrophotometrically measured reshyflectance and transmittance and calculated absorptance values of the leaves over the 500- to 2500-nanometer (nm) 4 wavelength interval (2) percent leaf-water contents (oven-dry weight basis) (3) leaf-thickness measurements and (4) optical and geometrical leaf parameters
Percent leaf-water contents of the 11 plant genera ranged from nO percent for isolateral ~ (palisade layers on both sides) eucalypshytus to 95 percent for succulent sedum and begonia leaves with storage cells on each side of a central chlorenchyma
Dorsiventral rose and compact corn leaves (no palisade cells) were thinnest (about 015 mm) and succulent sedum leaves were thickest (about 082 mm)
Spectral data for upper (adaxial) and lower (abaxial) leaf surfaces of all genera for 550- 800- 1000- 1450- 1650- 1950- ann 2200-nm wavelengths were appended Spectra of upper leaf surfaces of oleander corn hyacinth and eucalyptus were charted At the 1000-nm wavelength diffuse reflectance was highest for dorsiventral oleander and lowest for compact corn leaves transmittance was lowest for oleander and highest for corn leaves and absorptance for corn and oleander leaves was approximately 3 and 9 percent respectively rhe compact corn leaf with low light reflectance and high transmittance has fewer intercellular air spaces than the dorsi ventral oleander leaf
Because the interaction of plant genera with wavelength was small mean spectral measurements of 550- 800- 1000- 1450- 1650- 1950- and 2200-nm wavelengths were compared Lower leaf surfaces of dorsi ventral leaves had higher reflectance values than upper leaf surfaces indicating that the spongy parenchyma contribute more to light scattering than the palisade parenchyma
bull Both nanometer (nm) and micron (p) are used here to denote spectral wavelengths A nanometer is one thousandth of a micron and a micron is one thousandth of a millimeter
bull Botanical terms are definpd in the Glossary of Terms p 58
6 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of the leaf mesophyll This was substantiated by equal reflectance values of upper and lower surfaces of compact corn leaves
Thick leaves of oleander crinum fi~us sedum and Iigustrum had the lowest percent transmittarce Mean spectrophotometrishycally measured transmittance values for the above wavelengths were lower when light was passed from the top through the leaves than when light was passed through from the bottom The difference jn transmittance was caused by greater light diffusion by upper leaf surfaces since the spectrophotometer used irradishyates the specimen with direct light
Diffuse reflectance data were made absolute by correcting for decay of the magnesium-oxide standard on the spectrophotomshyeter and absorptance was calculated as 100 - [percent reshyflectance + percent transmittance] When data for wavelengths were averaged highest absorptance values of 606 582 591 and 583 percent were obtained for the thick dorsiventral ficus crinum ligustrum and oleander leaves respectively and lowest values of 404 and 390 percent were obtained for the thin comshypact corn and thin dorsiventral rose leaves respectively
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1450 nm) regions respectively At the 550-nm wavelengths reflectance was greater from the lower surface than from the upper surface of dorsiventral leaves indicating that the chloroplasts in the palisade cells absorbed light Lower and upper surface reflectances were the same for the compact corn leaves Considering upper leaf surfaces only thick succulent sedum and thick ficus leaves had the highest and lowest reflecshytance values of 20 and 8 percent respectively
Percent transmittance was lowest for ficus and highest for succulent begonia leaves Compact leaves of corn and succulent leaves of sedum and begonia with essentially a continuous mesoshyphyll arrangement had the loyrest light absorptance of approxishymately 70 percent Thick dorsiventral leaves of ficus oleander and ligustrum with multiseriide epidermal layers or multishypalisade layers had the highest light absorptance of 80 to 90 percent
At the 1000-nm wavelength reflectance values from upper and lower leaf surface measurements were essentially alike Comshypact corn leaves had the lowest reflectance (43 percent) and succulent sedum and dorsi ventral ficus oleander ligustrum and crinum leaves had the highest reflectance (53 percent) The 350
7 LEAF MESOPHYLLS OF TWENTY CROPS
percent transmithnce of oleander leaves was lowest and 545 percent for corn was highest The thin corn and rose leaves had the lowest absorptance values (2 to 3 percent) and the thick leaves of ligustrum ficus crinum sed urn and oleander had the highest values (8 to 11 percent)
Correlation coefficients were considered that accounted for at least 60 percent of the variation (r2 x 100) between leaf thickness and reflectance leaf thickness and absorptance leaf-water conshytent and refiectance and leaf-water content and absorptance Oleander eucalyptus and hyacinth leaves gave the highest coshyefficients among the plant genera studied In general co~ efficients were negative between water content and reflectance and between thickness and reflectance measurements and middotvith the main exception of eucalyptus coefficients were positive beshytween leaf-water content and absorptance and between thickness and absorptance calculations at 1450- 1650- 1950- and 2200shynm wavelengths
Experimental values of leaf reflectance and transmittance for the 11 genera were transformed into effective optical constants Such optical constants are useful in the prediction of reflectance phenomena associated with leaves either stacked in a spectroshyphotometer or arranged naturally in a plant canopy The index of refraction n was plotted against wavelength to obtain disshypersion curves The absorption coefficient k was shown to be equivalent to values determined previously for leaves from agrishycultural crops
Each of the 11 genera has been analyzed to obtain geometrical parameters that specify the amount of water and air in the leaf The water parameter is the thickness of liquid water necessary to produce the observed leaf absorption Observed and computed valuesmiddot of leaf-water thickness were obtained Agreement was good except for ligustrum crinum and sedum The air paramshyeter is the number of identical compact layers into which the equivalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance
A third parameter infinite reflectance is observed when leaves are piled sufficiently deep Infinite reflectance was tabulated at L65 p for all 11 genera Infinite reflectance was shown to be a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed
The literatUre dealing with the interaction of light with plant leaves and leaf mesophyl1 structure is reviewed in the technical
8 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
monograph by Gausman and others (15) and is not repeated here Attention is directed however to the research of Aboukhaled 6 who related the optical properties of leaves to their energy-balance photosynthesis and water-use efficiency
Materials and Methods Twenty plant genera were selected that are presently economshy
ically important or have the potential of becoming valuable in the Texas Lower Rio Grande Valley Pigweed was considered here as a crop rather than a weed because it is used by some farmers as a plow-under or green-manure crop The leaves of A
the selected genera varied in mesophyll arrangement thickness water content and other structural differences such as palisadeshylayer arrangement Leaf characteristics of the 20 crops and the families they represent are indicated in table 1 and typical photomicrographs of leaf transections are depicted in figure 1
All plants were field grown in the summer of 1970 except that lettuce and onions were purchased fresh at a local market soybeans and beans were grown in a greenhouse and wheat was grown during the 1969 season
Ten mature and healthy-appearing leaves were sampled from each of the 20 plant genera Immediately after excision leaves were wrapped in Saran or Glad-Wrap to minimize dehydration Leaves were wiped with a slightly dampened cloth to remove surface contaminants before spectrophotometric measurements The tubular onion leaf was split longitudinally and only oneshyhalf was measured
A Beckman Model DK-2A spectrophotometer equipped with a reflectance attachment was used to measure spectral diffuse
bull Aboukhaled A Optical properties of leaves in relation to their energyshybalance photosynthesis and water use efficiency (PhD thesis) University of Calif Library Davis 139 pp 1966
7 Trade names are used in this pUblication solely for the purpose of providing specific information Mention of a trade name does not constitute a guarantee or warranty of the product by the US Department of Agriculture or an endorsement by the Department over other products not mentioned
FIGURE I-Photomicrographs of leaf transections of 20 plant genera differing in leaf thickness mesophyll arrangement and other gross structural characteristics A avocado S bean C cantaloup D corniE cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
9 LEAF MESOPHYLLS OF TWENTY CROPS
FIGURE I-Continued
10 TECHNICAL BULLETIN 1middot165 US DEPT OF AGRICULTURE
FIGURE I-Continued
LEAF MESOPHYLLS OF TWENTY CROPS 11
reflectance and transmittance on adaxial (uppel) surfaces of single leaves over the 500- to 2500-nm wavelength interval Data have 1ieen corrected for decay of the magnesium-oxide standard (27) to give absolute radiometric data Absorptance was calculated from the absolute values as Percent absorptance = 100 - (percent reflectance + percent transmittance)
Measurements of leaf thickness and diffuse reflectance and transmittance and fixation of tissue were completed within 6 hours after leaves were harvested or obtained for each genus
Leaf thickness was measured with a linear-displacement transshyducer and digital voltmeter (17) Leaf area was determined with a planimeter except that area per leaf of corn sorghum and sugarcane was calculated by the method of Slickter Wearden and Pauli (29) and area per leaf of cotton was calculated by Tohnsons method (20) Percent leaf-water content was detershymined on an oven-dry weight basis by drying at 68deg C for 72 hours and cooling in a desiccator before final weighing Leaf thickness and water-content determinations were not made on wheat leaves
Tissue pieces taken near the center of leaves approximately one-half inch on either side of the midrib were fixed in formalinshyacetic acid-alcohol dehydrated with a tertiary butanol series embedded in paraffin stained with either the safranin-fast green or the safranin-fast green-orange G combinations (19) and transversally microtomed at 12- or 14- thickness The relatively thick transverse sections were used to accentuate intercellular spaces and thus enhance differences in mesophyll arrangeshyments among the crops Photomicrographs were obtained with a Zeiss Standard Universal Photomicroscope
Spectrophotometrically measured reflectance and transmittance and calculated absorptance of seven wavelengths (550 800 1000 14)0 1650 1950 and 2200 nm) were analyzed for variance (W) Duncans Multiple Range Test (7) was used to test differshyences among means of the seven wavelengths at the 5-percent probability level Standard deviation was calculated to compare the leaf reflectance transmittance and absorptance of the crops at the 550- and 1000-nm wavelengths Coefficients were calcushylated to evaluate the correlation of leaf thickness with leaf-water content Coefficients were also obtained for correlations of reshyflectance transmittance and absorptance with grams of water per cubic centimeter of leaf tissue leaf-water content on an ovenshydry weight basis and leaf thickness Correlation coefficients of plusmn 0775 were chosen as levels of significance because they acshy
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
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17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
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FIGURE 2-Continued
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000 o
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18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
The Leaf Mesophylls of Twenty Crops Their Light Spectra and
Optical and Geometrical Parameters1
H W GAUSMAN pl1nt physiologist W A ALLEN research physicist C L WIEGAND soil scientist D E ESCOBAR biological laboratory techshyncian R R RODRIGUEZ phy~ical science technician and A J RICHARDSON physicist Southern Region AgriC1tltural Research Service United States Department 0 Agricultlre
Summary Leaf mesophylls among 20 agricultural crops are compared
with (1) Spectrophotometrically measured percent reflectances and transmittances and calculated absorptances of the leaves over the 500- to 2500-nanometer (nm) wavelength interval (2) percent leaf-water contents (3) leaf thickness measureshyments and (4) opthal and geometrical leaf parameters Data are given as averages of 10 leaves (replications) for each crop The crops are Avocado bean cantaloup corn cotton lettuce okra onion orange peach pepper pigweed pumpkin sorghum soybean sugarcane sunflower tomato watermelon and wheat
Thick succulent lettuce leaves had the highest water content (970 percent) and dorsiventral avocado orange and peach and compact sugarcane leaves had the lowest water contents (range 606 to 724 percent)
Soybean peach pumpkin and pigweed leaves were thinnest (range 0140 to 0170 mm) and sunflower cantaloup lettuce and onion leaves were thickest (range 0407 to 0978 mm)
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1350 nm) spectral regions Data for lettuce were omitted because the leaves sampled middotere immature
1 The work was supported in part by the National Aeronautics and Space Administration und~r NASA Contract No R-09-038-002 Current Code No 160-75-01-07-10
2 The authors acknowledge the histological and technical assistance of Guadalupe Cardona Marcia Schupp and Ron Bowen Thaks are extended to the Amul Company Development Center Weslaco Tex for 3upplying the bean and soybean plants
1
2 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
The mean reflectance of the crop leaves at the 550-nm waveshylength was 13 3 plusmn 28 percent (one standard deviation) The majority of crops fell within the 133 pound 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane leaves (162 to 186 percent)
At the 550-nm wavelength transmittances of orange tomato and avocado (19 to 55 percent) and okra soybean onion (148 to 188 percent) fell outside the 98 plusmn 42 percent range
The mean absorptance for the crops at 550-nm wavelength was 769 plusmn 58 percent Thirteen crops fell within the 769 plusmn 58 percent range Sugarcane onion bean and peppel leaves with low absorptance (692 to 706 percent) and peach tomato avoshycado and orange leaves with high absorptance (829 to 879 pershycent) fell outside the 769 plusmn 58 percent range The leaves with high absorptance had well-differentiated dorsiventral mesophylls with many chloroplasts in their palisade cells Leaves with low absorptance had poorly differentiated mesophylls-less distincshytion between palisade and spongy parenchyma cells
The 1OOO-nm wavelength was llsed to evaluate the influence of leaf-mesophyll arrangement on near-infrared (750 to 1350 nm) light reflectance The mean reflectance of the crop leaves at the IOOO-nm wavelength was 480 plusmn 39 percent The reflectance of onion (38) percent) and orange and bean (556 and 562 pershycent respectively) fell outside this range However only oneshyhalf of the tubular onion leaf (split longitudinally) was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn sugarcane and soybean leaves had the lowest reflectances (451 to 460 percent) and dOlsiventral bean orange and pepper leaves with very porous mesophyll had the highest reflectances (510 to 562 percent)
At the IOOO-nm wavelength the mean transmittance of all crop leaves was 479 plusmn 37 percent All crops fell within this rang-e except orange (389 percent) and bean (420 percent) and soybean pigweed and onion (522 to 540 percent)
The mean absorptance of all crop leaves at the 1000-nm waveshylength was 40 plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 pershycent) fell outside the 40 plusmn 17 percent range
Correlation coefficients equal to or larger than plusmn 0775 are conshysidered that accounted for at least 60 percent of the variation (0775 z x 100) between comparisons Negative coefficients exshyceeding - 0775 were obtained for correlations between light reshy
LEAF MESOPHYLLS OF TWENTY CROPS 3
flectance and percent leaf-water content for sugarcane at 1450- 1650- and 2200-nm for corn at 550- and 1450-nm for pigweed at 1450-nm and for tomato at 1450- and 2200-nm wavelengths Soybean had positive coefficients exceeding 0775 for the correlashytion between reflectance and leaf thickness at the 550- 800- and 1OOO-nm wavelengths and a negative coefficient that exshyceeded -077f5 for the correlation between transmittance and leaf thickness at the 1000-nm wavelength Soybean leaves also had large negative coefficients for the correlation between reshyflectance and leaf thickness at the 1450- 1950- and 2200-nm wavelengths and for the correlation between transmittance and leaf thickness at the 1450- 1650- 1950- and 2200-nm waveshylengths Peach pigweed tomato bean and onion crops also had high negative coefficients for t~e correlation between transmitshytance and leaf thickness at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths High positive coefficients were obtained for the correlation between leaf thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
The grams of water per cubic centimeter of leaf tissue were calculated for each crop leaf used except wheat There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue For transmittance coefficients exceeded -0775 only for okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and brams of water per cubic centimeter of leaf tissue gave high posishytive coefficients for okra leaves at 1450 1650 and 2200 nm
Experimental values of leaf reflectance and transmittance for the 20 crops have been transformed into effective optical conshystants Such optical constants are useful in the prediction of reshyflectance phenomena associated with leaves either stacked in a spectrophotometer or arranged naturally in a plant canopy The index of refraction n is plotted against wavelength to obtain disshypersion curves The values for the absorption coefficient k that are tabulated for the various crops are equivalent to values detershymined previously for leaves from agricultural crops
The dispersion curves of most of the crop leaves were reshymarkably similar in shape and in relatively close confidence bands Onion pigweed and lettuce were exceptions but only one-half of the tubular onion leaves (split longitudinally) was used lettuce leaves were immature and veins of pigweed leaves are surrounded by large cubical parenchymatous cells
4 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Sixteen of the 20 crops were analyzed to determine the thickshyness of water necessary to produce the observed leaf absorption and the number of identical compact layers into which the equivshyalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance Sugarcane corn sorghum and wheat leaves were not included because laborashytory determinations of thickness and water content were not made on entire leaves There was no statistically significant difshyference between observed and computed values for leaf water for 10 of the crops Pumpkin avocado okra tomato cantaloup and lettuce showed differences but they were not highly significant
The limiting value of reflectance from leaves piled sufficiently deep is termed infinite reflectance This parameter is a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed Infinite reflectance has been tabulated at 165 p for the 20 crops
Introduction To interpret remote-sensing data from aircraft and spacecraft
thE reflectance produced by features on the ~arths surface must be understood (33)3 The specific problem in agriculture is interpretation of reflectance produced by vegetation usuaIIy supershyimposed on a soil background Plant leaves yield most of the signal measured by remote sensors in aircraft a1 rl spacecraft Therefore they are of prime interest in characterizing vegetashytion and their interaction with electromagnetic radiation must be understood
The purpose of research reported here was to relate the leaf mesophyll structure of 20 important agricultural plant genera to their light spectra and to optical and geometrical parameters This report is a sequel to a technical monograph by Gausman and others (15) which presented research results on the spectralshyenergy relations of leaves for 11 plant genera characterized by marked differences in leaf-mesophyll arrangements The research was based on the hypothesis that leaf-mesophyll arrangements influence spectral-energy relations of leaves and plant canopies Previous research had considered only the relation of light reflecshytance to leaf surface morphologies (28) and to isobilateral leaves (18)
Plants studied were corn (Zea mays L) banana (Musa acuminata Colla (M cavendishii Lamb) I begonia (Begonia C1tshy
bull Italic numbers in partnthfSfR refer to Literature Cited p 43
LEAF MESOPHYLLS OF TWENTY CROPS 5
cullata Willd (E sernperlo1ens Link amp Otto) eucalyptus (Eucalllptus camaldulensis Dehnh (E rostrata Schlecht) rose (Rosa val unknown) l hyacinth (Eichhornia crassipes (Mart) Solms sedum (Sedum spectabile Boreau) ficus (Ficus elastica
~ Roxb ex Hornem) oleander (Nerium oleander L Ligustrum (Lig1lstrnm l1lcidum Ait) and crinum (Crinum fimbriat1llum Baker)
Differences in leaf mesophylls among the 11 plant genera (Hi) were compared with (1) Spectrophotometrically measured reshyflectance and transmittance and calculated absorptance values of the leaves over the 500- to 2500-nanometer (nm) 4 wavelength interval (2) percent leaf-water contents (oven-dry weight basis) (3) leaf-thickness measurements and (4) optical and geometrical leaf parameters
Percent leaf-water contents of the 11 plant genera ranged from nO percent for isolateral ~ (palisade layers on both sides) eucalypshytus to 95 percent for succulent sedum and begonia leaves with storage cells on each side of a central chlorenchyma
Dorsiventral rose and compact corn leaves (no palisade cells) were thinnest (about 015 mm) and succulent sedum leaves were thickest (about 082 mm)
Spectral data for upper (adaxial) and lower (abaxial) leaf surfaces of all genera for 550- 800- 1000- 1450- 1650- 1950- ann 2200-nm wavelengths were appended Spectra of upper leaf surfaces of oleander corn hyacinth and eucalyptus were charted At the 1000-nm wavelength diffuse reflectance was highest for dorsiventral oleander and lowest for compact corn leaves transmittance was lowest for oleander and highest for corn leaves and absorptance for corn and oleander leaves was approximately 3 and 9 percent respectively rhe compact corn leaf with low light reflectance and high transmittance has fewer intercellular air spaces than the dorsi ventral oleander leaf
Because the interaction of plant genera with wavelength was small mean spectral measurements of 550- 800- 1000- 1450- 1650- 1950- and 2200-nm wavelengths were compared Lower leaf surfaces of dorsi ventral leaves had higher reflectance values than upper leaf surfaces indicating that the spongy parenchyma contribute more to light scattering than the palisade parenchyma
bull Both nanometer (nm) and micron (p) are used here to denote spectral wavelengths A nanometer is one thousandth of a micron and a micron is one thousandth of a millimeter
bull Botanical terms are definpd in the Glossary of Terms p 58
6 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of the leaf mesophyll This was substantiated by equal reflectance values of upper and lower surfaces of compact corn leaves
Thick leaves of oleander crinum fi~us sedum and Iigustrum had the lowest percent transmittarce Mean spectrophotometrishycally measured transmittance values for the above wavelengths were lower when light was passed from the top through the leaves than when light was passed through from the bottom The difference jn transmittance was caused by greater light diffusion by upper leaf surfaces since the spectrophotometer used irradishyates the specimen with direct light
Diffuse reflectance data were made absolute by correcting for decay of the magnesium-oxide standard on the spectrophotomshyeter and absorptance was calculated as 100 - [percent reshyflectance + percent transmittance] When data for wavelengths were averaged highest absorptance values of 606 582 591 and 583 percent were obtained for the thick dorsiventral ficus crinum ligustrum and oleander leaves respectively and lowest values of 404 and 390 percent were obtained for the thin comshypact corn and thin dorsiventral rose leaves respectively
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1450 nm) regions respectively At the 550-nm wavelengths reflectance was greater from the lower surface than from the upper surface of dorsiventral leaves indicating that the chloroplasts in the palisade cells absorbed light Lower and upper surface reflectances were the same for the compact corn leaves Considering upper leaf surfaces only thick succulent sedum and thick ficus leaves had the highest and lowest reflecshytance values of 20 and 8 percent respectively
Percent transmittance was lowest for ficus and highest for succulent begonia leaves Compact leaves of corn and succulent leaves of sedum and begonia with essentially a continuous mesoshyphyll arrangement had the loyrest light absorptance of approxishymately 70 percent Thick dorsiventral leaves of ficus oleander and ligustrum with multiseriide epidermal layers or multishypalisade layers had the highest light absorptance of 80 to 90 percent
At the 1000-nm wavelength reflectance values from upper and lower leaf surface measurements were essentially alike Comshypact corn leaves had the lowest reflectance (43 percent) and succulent sedum and dorsi ventral ficus oleander ligustrum and crinum leaves had the highest reflectance (53 percent) The 350
7 LEAF MESOPHYLLS OF TWENTY CROPS
percent transmithnce of oleander leaves was lowest and 545 percent for corn was highest The thin corn and rose leaves had the lowest absorptance values (2 to 3 percent) and the thick leaves of ligustrum ficus crinum sed urn and oleander had the highest values (8 to 11 percent)
Correlation coefficients were considered that accounted for at least 60 percent of the variation (r2 x 100) between leaf thickness and reflectance leaf thickness and absorptance leaf-water conshytent and refiectance and leaf-water content and absorptance Oleander eucalyptus and hyacinth leaves gave the highest coshyefficients among the plant genera studied In general co~ efficients were negative between water content and reflectance and between thickness and reflectance measurements and middotvith the main exception of eucalyptus coefficients were positive beshytween leaf-water content and absorptance and between thickness and absorptance calculations at 1450- 1650- 1950- and 2200shynm wavelengths
Experimental values of leaf reflectance and transmittance for the 11 genera were transformed into effective optical constants Such optical constants are useful in the prediction of reflectance phenomena associated with leaves either stacked in a spectroshyphotometer or arranged naturally in a plant canopy The index of refraction n was plotted against wavelength to obtain disshypersion curves The absorption coefficient k was shown to be equivalent to values determined previously for leaves from agrishycultural crops
Each of the 11 genera has been analyzed to obtain geometrical parameters that specify the amount of water and air in the leaf The water parameter is the thickness of liquid water necessary to produce the observed leaf absorption Observed and computed valuesmiddot of leaf-water thickness were obtained Agreement was good except for ligustrum crinum and sedum The air paramshyeter is the number of identical compact layers into which the equivalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance
A third parameter infinite reflectance is observed when leaves are piled sufficiently deep Infinite reflectance was tabulated at L65 p for all 11 genera Infinite reflectance was shown to be a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed
The literatUre dealing with the interaction of light with plant leaves and leaf mesophyl1 structure is reviewed in the technical
8 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
monograph by Gausman and others (15) and is not repeated here Attention is directed however to the research of Aboukhaled 6 who related the optical properties of leaves to their energy-balance photosynthesis and water-use efficiency
Materials and Methods Twenty plant genera were selected that are presently economshy
ically important or have the potential of becoming valuable in the Texas Lower Rio Grande Valley Pigweed was considered here as a crop rather than a weed because it is used by some farmers as a plow-under or green-manure crop The leaves of A
the selected genera varied in mesophyll arrangement thickness water content and other structural differences such as palisadeshylayer arrangement Leaf characteristics of the 20 crops and the families they represent are indicated in table 1 and typical photomicrographs of leaf transections are depicted in figure 1
All plants were field grown in the summer of 1970 except that lettuce and onions were purchased fresh at a local market soybeans and beans were grown in a greenhouse and wheat was grown during the 1969 season
Ten mature and healthy-appearing leaves were sampled from each of the 20 plant genera Immediately after excision leaves were wrapped in Saran or Glad-Wrap to minimize dehydration Leaves were wiped with a slightly dampened cloth to remove surface contaminants before spectrophotometric measurements The tubular onion leaf was split longitudinally and only oneshyhalf was measured
A Beckman Model DK-2A spectrophotometer equipped with a reflectance attachment was used to measure spectral diffuse
bull Aboukhaled A Optical properties of leaves in relation to their energyshybalance photosynthesis and water use efficiency (PhD thesis) University of Calif Library Davis 139 pp 1966
7 Trade names are used in this pUblication solely for the purpose of providing specific information Mention of a trade name does not constitute a guarantee or warranty of the product by the US Department of Agriculture or an endorsement by the Department over other products not mentioned
FIGURE I-Photomicrographs of leaf transections of 20 plant genera differing in leaf thickness mesophyll arrangement and other gross structural characteristics A avocado S bean C cantaloup D corniE cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
9 LEAF MESOPHYLLS OF TWENTY CROPS
FIGURE I-Continued
10 TECHNICAL BULLETIN 1middot165 US DEPT OF AGRICULTURE
FIGURE I-Continued
LEAF MESOPHYLLS OF TWENTY CROPS 11
reflectance and transmittance on adaxial (uppel) surfaces of single leaves over the 500- to 2500-nm wavelength interval Data have 1ieen corrected for decay of the magnesium-oxide standard (27) to give absolute radiometric data Absorptance was calculated from the absolute values as Percent absorptance = 100 - (percent reflectance + percent transmittance)
Measurements of leaf thickness and diffuse reflectance and transmittance and fixation of tissue were completed within 6 hours after leaves were harvested or obtained for each genus
Leaf thickness was measured with a linear-displacement transshyducer and digital voltmeter (17) Leaf area was determined with a planimeter except that area per leaf of corn sorghum and sugarcane was calculated by the method of Slickter Wearden and Pauli (29) and area per leaf of cotton was calculated by Tohnsons method (20) Percent leaf-water content was detershymined on an oven-dry weight basis by drying at 68deg C for 72 hours and cooling in a desiccator before final weighing Leaf thickness and water-content determinations were not made on wheat leaves
Tissue pieces taken near the center of leaves approximately one-half inch on either side of the midrib were fixed in formalinshyacetic acid-alcohol dehydrated with a tertiary butanol series embedded in paraffin stained with either the safranin-fast green or the safranin-fast green-orange G combinations (19) and transversally microtomed at 12- or 14- thickness The relatively thick transverse sections were used to accentuate intercellular spaces and thus enhance differences in mesophyll arrangeshyments among the crops Photomicrographs were obtained with a Zeiss Standard Universal Photomicroscope
Spectrophotometrically measured reflectance and transmittance and calculated absorptance of seven wavelengths (550 800 1000 14)0 1650 1950 and 2200 nm) were analyzed for variance (W) Duncans Multiple Range Test (7) was used to test differshyences among means of the seven wavelengths at the 5-percent probability level Standard deviation was calculated to compare the leaf reflectance transmittance and absorptance of the crops at the 550- and 1000-nm wavelengths Coefficients were calcushylated to evaluate the correlation of leaf thickness with leaf-water content Coefficients were also obtained for correlations of reshyflectance transmittance and absorptance with grams of water per cubic centimeter of leaf tissue leaf-water content on an ovenshydry weight basis and leaf thickness Correlation coefficients of plusmn 0775 were chosen as levels of significance because they acshy
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
~ID~O~O~--~i500~I~__~W~~--~aoo
500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
100 10
TRAHSiMTlAHCE
20
i i
401 ~ 1 ~
O ~
70
SO ~ REFLpoundCT~ 00
o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
N
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
p
500 1000 -~------- ~o
100
140
~50 460 170 -j80
90
0 RJOO
o---middotiir-~LiOo----2000L---2100
R
IDO~ 100
TRANSMfTTANCE
i ~
A8SORPT~CE
~~ 1 80 j
III REFLpoundCTANC( 90
Dshy~
aa
T
o
o~
Q
70 i 60~
I
~ ~u 201shy
bull Ill
o~
s
1000
IOO
wlllVflfJrtGTH fWI)
--oDIGTl1
~o
REFUclANCE
FIGURE 2-Continued
_~
2DOO
(HOO __--J
Z300
2gt00
10
120 1 30
1 ~ ~o ~ 60
10
bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
2 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
The mean reflectance of the crop leaves at the 550-nm waveshylength was 13 3 plusmn 28 percent (one standard deviation) The majority of crops fell within the 133 pound 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane leaves (162 to 186 percent)
At the 550-nm wavelength transmittances of orange tomato and avocado (19 to 55 percent) and okra soybean onion (148 to 188 percent) fell outside the 98 plusmn 42 percent range
The mean absorptance for the crops at 550-nm wavelength was 769 plusmn 58 percent Thirteen crops fell within the 769 plusmn 58 percent range Sugarcane onion bean and peppel leaves with low absorptance (692 to 706 percent) and peach tomato avoshycado and orange leaves with high absorptance (829 to 879 pershycent) fell outside the 769 plusmn 58 percent range The leaves with high absorptance had well-differentiated dorsiventral mesophylls with many chloroplasts in their palisade cells Leaves with low absorptance had poorly differentiated mesophylls-less distincshytion between palisade and spongy parenchyma cells
The 1OOO-nm wavelength was llsed to evaluate the influence of leaf-mesophyll arrangement on near-infrared (750 to 1350 nm) light reflectance The mean reflectance of the crop leaves at the IOOO-nm wavelength was 480 plusmn 39 percent The reflectance of onion (38) percent) and orange and bean (556 and 562 pershycent respectively) fell outside this range However only oneshyhalf of the tubular onion leaf (split longitudinally) was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn sugarcane and soybean leaves had the lowest reflectances (451 to 460 percent) and dOlsiventral bean orange and pepper leaves with very porous mesophyll had the highest reflectances (510 to 562 percent)
At the IOOO-nm wavelength the mean transmittance of all crop leaves was 479 plusmn 37 percent All crops fell within this rang-e except orange (389 percent) and bean (420 percent) and soybean pigweed and onion (522 to 540 percent)
The mean absorptance of all crop leaves at the 1000-nm waveshylength was 40 plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 pershycent) fell outside the 40 plusmn 17 percent range
Correlation coefficients equal to or larger than plusmn 0775 are conshysidered that accounted for at least 60 percent of the variation (0775 z x 100) between comparisons Negative coefficients exshyceeding - 0775 were obtained for correlations between light reshy
LEAF MESOPHYLLS OF TWENTY CROPS 3
flectance and percent leaf-water content for sugarcane at 1450- 1650- and 2200-nm for corn at 550- and 1450-nm for pigweed at 1450-nm and for tomato at 1450- and 2200-nm wavelengths Soybean had positive coefficients exceeding 0775 for the correlashytion between reflectance and leaf thickness at the 550- 800- and 1OOO-nm wavelengths and a negative coefficient that exshyceeded -077f5 for the correlation between transmittance and leaf thickness at the 1000-nm wavelength Soybean leaves also had large negative coefficients for the correlation between reshyflectance and leaf thickness at the 1450- 1950- and 2200-nm wavelengths and for the correlation between transmittance and leaf thickness at the 1450- 1650- 1950- and 2200-nm waveshylengths Peach pigweed tomato bean and onion crops also had high negative coefficients for t~e correlation between transmitshytance and leaf thickness at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths High positive coefficients were obtained for the correlation between leaf thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
The grams of water per cubic centimeter of leaf tissue were calculated for each crop leaf used except wheat There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue For transmittance coefficients exceeded -0775 only for okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and brams of water per cubic centimeter of leaf tissue gave high posishytive coefficients for okra leaves at 1450 1650 and 2200 nm
Experimental values of leaf reflectance and transmittance for the 20 crops have been transformed into effective optical conshystants Such optical constants are useful in the prediction of reshyflectance phenomena associated with leaves either stacked in a spectrophotometer or arranged naturally in a plant canopy The index of refraction n is plotted against wavelength to obtain disshypersion curves The values for the absorption coefficient k that are tabulated for the various crops are equivalent to values detershymined previously for leaves from agricultural crops
The dispersion curves of most of the crop leaves were reshymarkably similar in shape and in relatively close confidence bands Onion pigweed and lettuce were exceptions but only one-half of the tubular onion leaves (split longitudinally) was used lettuce leaves were immature and veins of pigweed leaves are surrounded by large cubical parenchymatous cells
4 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Sixteen of the 20 crops were analyzed to determine the thickshyness of water necessary to produce the observed leaf absorption and the number of identical compact layers into which the equivshyalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance Sugarcane corn sorghum and wheat leaves were not included because laborashytory determinations of thickness and water content were not made on entire leaves There was no statistically significant difshyference between observed and computed values for leaf water for 10 of the crops Pumpkin avocado okra tomato cantaloup and lettuce showed differences but they were not highly significant
The limiting value of reflectance from leaves piled sufficiently deep is termed infinite reflectance This parameter is a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed Infinite reflectance has been tabulated at 165 p for the 20 crops
Introduction To interpret remote-sensing data from aircraft and spacecraft
thE reflectance produced by features on the ~arths surface must be understood (33)3 The specific problem in agriculture is interpretation of reflectance produced by vegetation usuaIIy supershyimposed on a soil background Plant leaves yield most of the signal measured by remote sensors in aircraft a1 rl spacecraft Therefore they are of prime interest in characterizing vegetashytion and their interaction with electromagnetic radiation must be understood
The purpose of research reported here was to relate the leaf mesophyll structure of 20 important agricultural plant genera to their light spectra and to optical and geometrical parameters This report is a sequel to a technical monograph by Gausman and others (15) which presented research results on the spectralshyenergy relations of leaves for 11 plant genera characterized by marked differences in leaf-mesophyll arrangements The research was based on the hypothesis that leaf-mesophyll arrangements influence spectral-energy relations of leaves and plant canopies Previous research had considered only the relation of light reflecshytance to leaf surface morphologies (28) and to isobilateral leaves (18)
Plants studied were corn (Zea mays L) banana (Musa acuminata Colla (M cavendishii Lamb) I begonia (Begonia C1tshy
bull Italic numbers in partnthfSfR refer to Literature Cited p 43
LEAF MESOPHYLLS OF TWENTY CROPS 5
cullata Willd (E sernperlo1ens Link amp Otto) eucalyptus (Eucalllptus camaldulensis Dehnh (E rostrata Schlecht) rose (Rosa val unknown) l hyacinth (Eichhornia crassipes (Mart) Solms sedum (Sedum spectabile Boreau) ficus (Ficus elastica
~ Roxb ex Hornem) oleander (Nerium oleander L Ligustrum (Lig1lstrnm l1lcidum Ait) and crinum (Crinum fimbriat1llum Baker)
Differences in leaf mesophylls among the 11 plant genera (Hi) were compared with (1) Spectrophotometrically measured reshyflectance and transmittance and calculated absorptance values of the leaves over the 500- to 2500-nanometer (nm) 4 wavelength interval (2) percent leaf-water contents (oven-dry weight basis) (3) leaf-thickness measurements and (4) optical and geometrical leaf parameters
Percent leaf-water contents of the 11 plant genera ranged from nO percent for isolateral ~ (palisade layers on both sides) eucalypshytus to 95 percent for succulent sedum and begonia leaves with storage cells on each side of a central chlorenchyma
Dorsiventral rose and compact corn leaves (no palisade cells) were thinnest (about 015 mm) and succulent sedum leaves were thickest (about 082 mm)
Spectral data for upper (adaxial) and lower (abaxial) leaf surfaces of all genera for 550- 800- 1000- 1450- 1650- 1950- ann 2200-nm wavelengths were appended Spectra of upper leaf surfaces of oleander corn hyacinth and eucalyptus were charted At the 1000-nm wavelength diffuse reflectance was highest for dorsiventral oleander and lowest for compact corn leaves transmittance was lowest for oleander and highest for corn leaves and absorptance for corn and oleander leaves was approximately 3 and 9 percent respectively rhe compact corn leaf with low light reflectance and high transmittance has fewer intercellular air spaces than the dorsi ventral oleander leaf
Because the interaction of plant genera with wavelength was small mean spectral measurements of 550- 800- 1000- 1450- 1650- 1950- and 2200-nm wavelengths were compared Lower leaf surfaces of dorsi ventral leaves had higher reflectance values than upper leaf surfaces indicating that the spongy parenchyma contribute more to light scattering than the palisade parenchyma
bull Both nanometer (nm) and micron (p) are used here to denote spectral wavelengths A nanometer is one thousandth of a micron and a micron is one thousandth of a millimeter
bull Botanical terms are definpd in the Glossary of Terms p 58
6 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of the leaf mesophyll This was substantiated by equal reflectance values of upper and lower surfaces of compact corn leaves
Thick leaves of oleander crinum fi~us sedum and Iigustrum had the lowest percent transmittarce Mean spectrophotometrishycally measured transmittance values for the above wavelengths were lower when light was passed from the top through the leaves than when light was passed through from the bottom The difference jn transmittance was caused by greater light diffusion by upper leaf surfaces since the spectrophotometer used irradishyates the specimen with direct light
Diffuse reflectance data were made absolute by correcting for decay of the magnesium-oxide standard on the spectrophotomshyeter and absorptance was calculated as 100 - [percent reshyflectance + percent transmittance] When data for wavelengths were averaged highest absorptance values of 606 582 591 and 583 percent were obtained for the thick dorsiventral ficus crinum ligustrum and oleander leaves respectively and lowest values of 404 and 390 percent were obtained for the thin comshypact corn and thin dorsiventral rose leaves respectively
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1450 nm) regions respectively At the 550-nm wavelengths reflectance was greater from the lower surface than from the upper surface of dorsiventral leaves indicating that the chloroplasts in the palisade cells absorbed light Lower and upper surface reflectances were the same for the compact corn leaves Considering upper leaf surfaces only thick succulent sedum and thick ficus leaves had the highest and lowest reflecshytance values of 20 and 8 percent respectively
Percent transmittance was lowest for ficus and highest for succulent begonia leaves Compact leaves of corn and succulent leaves of sedum and begonia with essentially a continuous mesoshyphyll arrangement had the loyrest light absorptance of approxishymately 70 percent Thick dorsiventral leaves of ficus oleander and ligustrum with multiseriide epidermal layers or multishypalisade layers had the highest light absorptance of 80 to 90 percent
At the 1000-nm wavelength reflectance values from upper and lower leaf surface measurements were essentially alike Comshypact corn leaves had the lowest reflectance (43 percent) and succulent sedum and dorsi ventral ficus oleander ligustrum and crinum leaves had the highest reflectance (53 percent) The 350
7 LEAF MESOPHYLLS OF TWENTY CROPS
percent transmithnce of oleander leaves was lowest and 545 percent for corn was highest The thin corn and rose leaves had the lowest absorptance values (2 to 3 percent) and the thick leaves of ligustrum ficus crinum sed urn and oleander had the highest values (8 to 11 percent)
Correlation coefficients were considered that accounted for at least 60 percent of the variation (r2 x 100) between leaf thickness and reflectance leaf thickness and absorptance leaf-water conshytent and refiectance and leaf-water content and absorptance Oleander eucalyptus and hyacinth leaves gave the highest coshyefficients among the plant genera studied In general co~ efficients were negative between water content and reflectance and between thickness and reflectance measurements and middotvith the main exception of eucalyptus coefficients were positive beshytween leaf-water content and absorptance and between thickness and absorptance calculations at 1450- 1650- 1950- and 2200shynm wavelengths
Experimental values of leaf reflectance and transmittance for the 11 genera were transformed into effective optical constants Such optical constants are useful in the prediction of reflectance phenomena associated with leaves either stacked in a spectroshyphotometer or arranged naturally in a plant canopy The index of refraction n was plotted against wavelength to obtain disshypersion curves The absorption coefficient k was shown to be equivalent to values determined previously for leaves from agrishycultural crops
Each of the 11 genera has been analyzed to obtain geometrical parameters that specify the amount of water and air in the leaf The water parameter is the thickness of liquid water necessary to produce the observed leaf absorption Observed and computed valuesmiddot of leaf-water thickness were obtained Agreement was good except for ligustrum crinum and sedum The air paramshyeter is the number of identical compact layers into which the equivalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance
A third parameter infinite reflectance is observed when leaves are piled sufficiently deep Infinite reflectance was tabulated at L65 p for all 11 genera Infinite reflectance was shown to be a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed
The literatUre dealing with the interaction of light with plant leaves and leaf mesophyl1 structure is reviewed in the technical
8 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
monograph by Gausman and others (15) and is not repeated here Attention is directed however to the research of Aboukhaled 6 who related the optical properties of leaves to their energy-balance photosynthesis and water-use efficiency
Materials and Methods Twenty plant genera were selected that are presently economshy
ically important or have the potential of becoming valuable in the Texas Lower Rio Grande Valley Pigweed was considered here as a crop rather than a weed because it is used by some farmers as a plow-under or green-manure crop The leaves of A
the selected genera varied in mesophyll arrangement thickness water content and other structural differences such as palisadeshylayer arrangement Leaf characteristics of the 20 crops and the families they represent are indicated in table 1 and typical photomicrographs of leaf transections are depicted in figure 1
All plants were field grown in the summer of 1970 except that lettuce and onions were purchased fresh at a local market soybeans and beans were grown in a greenhouse and wheat was grown during the 1969 season
Ten mature and healthy-appearing leaves were sampled from each of the 20 plant genera Immediately after excision leaves were wrapped in Saran or Glad-Wrap to minimize dehydration Leaves were wiped with a slightly dampened cloth to remove surface contaminants before spectrophotometric measurements The tubular onion leaf was split longitudinally and only oneshyhalf was measured
A Beckman Model DK-2A spectrophotometer equipped with a reflectance attachment was used to measure spectral diffuse
bull Aboukhaled A Optical properties of leaves in relation to their energyshybalance photosynthesis and water use efficiency (PhD thesis) University of Calif Library Davis 139 pp 1966
7 Trade names are used in this pUblication solely for the purpose of providing specific information Mention of a trade name does not constitute a guarantee or warranty of the product by the US Department of Agriculture or an endorsement by the Department over other products not mentioned
FIGURE I-Photomicrographs of leaf transections of 20 plant genera differing in leaf thickness mesophyll arrangement and other gross structural characteristics A avocado S bean C cantaloup D corniE cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
9 LEAF MESOPHYLLS OF TWENTY CROPS
FIGURE I-Continued
10 TECHNICAL BULLETIN 1middot165 US DEPT OF AGRICULTURE
FIGURE I-Continued
LEAF MESOPHYLLS OF TWENTY CROPS 11
reflectance and transmittance on adaxial (uppel) surfaces of single leaves over the 500- to 2500-nm wavelength interval Data have 1ieen corrected for decay of the magnesium-oxide standard (27) to give absolute radiometric data Absorptance was calculated from the absolute values as Percent absorptance = 100 - (percent reflectance + percent transmittance)
Measurements of leaf thickness and diffuse reflectance and transmittance and fixation of tissue were completed within 6 hours after leaves were harvested or obtained for each genus
Leaf thickness was measured with a linear-displacement transshyducer and digital voltmeter (17) Leaf area was determined with a planimeter except that area per leaf of corn sorghum and sugarcane was calculated by the method of Slickter Wearden and Pauli (29) and area per leaf of cotton was calculated by Tohnsons method (20) Percent leaf-water content was detershymined on an oven-dry weight basis by drying at 68deg C for 72 hours and cooling in a desiccator before final weighing Leaf thickness and water-content determinations were not made on wheat leaves
Tissue pieces taken near the center of leaves approximately one-half inch on either side of the midrib were fixed in formalinshyacetic acid-alcohol dehydrated with a tertiary butanol series embedded in paraffin stained with either the safranin-fast green or the safranin-fast green-orange G combinations (19) and transversally microtomed at 12- or 14- thickness The relatively thick transverse sections were used to accentuate intercellular spaces and thus enhance differences in mesophyll arrangeshyments among the crops Photomicrographs were obtained with a Zeiss Standard Universal Photomicroscope
Spectrophotometrically measured reflectance and transmittance and calculated absorptance of seven wavelengths (550 800 1000 14)0 1650 1950 and 2200 nm) were analyzed for variance (W) Duncans Multiple Range Test (7) was used to test differshyences among means of the seven wavelengths at the 5-percent probability level Standard deviation was calculated to compare the leaf reflectance transmittance and absorptance of the crops at the 550- and 1000-nm wavelengths Coefficients were calcushylated to evaluate the correlation of leaf thickness with leaf-water content Coefficients were also obtained for correlations of reshyflectance transmittance and absorptance with grams of water per cubic centimeter of leaf tissue leaf-water content on an ovenshydry weight basis and leaf thickness Correlation coefficients of plusmn 0775 were chosen as levels of significance because they acshy
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
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500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
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o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
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17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
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TRANSMfTTANCE
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III REFLpoundCTANC( 90
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FIGURE 2-Continued
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bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
LEAF MESOPHYLLS OF TWENTY CROPS 3
flectance and percent leaf-water content for sugarcane at 1450- 1650- and 2200-nm for corn at 550- and 1450-nm for pigweed at 1450-nm and for tomato at 1450- and 2200-nm wavelengths Soybean had positive coefficients exceeding 0775 for the correlashytion between reflectance and leaf thickness at the 550- 800- and 1OOO-nm wavelengths and a negative coefficient that exshyceeded -077f5 for the correlation between transmittance and leaf thickness at the 1000-nm wavelength Soybean leaves also had large negative coefficients for the correlation between reshyflectance and leaf thickness at the 1450- 1950- and 2200-nm wavelengths and for the correlation between transmittance and leaf thickness at the 1450- 1650- 1950- and 2200-nm waveshylengths Peach pigweed tomato bean and onion crops also had high negative coefficients for t~e correlation between transmitshytance and leaf thickness at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths High positive coefficients were obtained for the correlation between leaf thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
The grams of water per cubic centimeter of leaf tissue were calculated for each crop leaf used except wheat There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue For transmittance coefficients exceeded -0775 only for okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and brams of water per cubic centimeter of leaf tissue gave high posishytive coefficients for okra leaves at 1450 1650 and 2200 nm
Experimental values of leaf reflectance and transmittance for the 20 crops have been transformed into effective optical conshystants Such optical constants are useful in the prediction of reshyflectance phenomena associated with leaves either stacked in a spectrophotometer or arranged naturally in a plant canopy The index of refraction n is plotted against wavelength to obtain disshypersion curves The values for the absorption coefficient k that are tabulated for the various crops are equivalent to values detershymined previously for leaves from agricultural crops
The dispersion curves of most of the crop leaves were reshymarkably similar in shape and in relatively close confidence bands Onion pigweed and lettuce were exceptions but only one-half of the tubular onion leaves (split longitudinally) was used lettuce leaves were immature and veins of pigweed leaves are surrounded by large cubical parenchymatous cells
4 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Sixteen of the 20 crops were analyzed to determine the thickshyness of water necessary to produce the observed leaf absorption and the number of identical compact layers into which the equivshyalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance Sugarcane corn sorghum and wheat leaves were not included because laborashytory determinations of thickness and water content were not made on entire leaves There was no statistically significant difshyference between observed and computed values for leaf water for 10 of the crops Pumpkin avocado okra tomato cantaloup and lettuce showed differences but they were not highly significant
The limiting value of reflectance from leaves piled sufficiently deep is termed infinite reflectance This parameter is a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed Infinite reflectance has been tabulated at 165 p for the 20 crops
Introduction To interpret remote-sensing data from aircraft and spacecraft
thE reflectance produced by features on the ~arths surface must be understood (33)3 The specific problem in agriculture is interpretation of reflectance produced by vegetation usuaIIy supershyimposed on a soil background Plant leaves yield most of the signal measured by remote sensors in aircraft a1 rl spacecraft Therefore they are of prime interest in characterizing vegetashytion and their interaction with electromagnetic radiation must be understood
The purpose of research reported here was to relate the leaf mesophyll structure of 20 important agricultural plant genera to their light spectra and to optical and geometrical parameters This report is a sequel to a technical monograph by Gausman and others (15) which presented research results on the spectralshyenergy relations of leaves for 11 plant genera characterized by marked differences in leaf-mesophyll arrangements The research was based on the hypothesis that leaf-mesophyll arrangements influence spectral-energy relations of leaves and plant canopies Previous research had considered only the relation of light reflecshytance to leaf surface morphologies (28) and to isobilateral leaves (18)
Plants studied were corn (Zea mays L) banana (Musa acuminata Colla (M cavendishii Lamb) I begonia (Begonia C1tshy
bull Italic numbers in partnthfSfR refer to Literature Cited p 43
LEAF MESOPHYLLS OF TWENTY CROPS 5
cullata Willd (E sernperlo1ens Link amp Otto) eucalyptus (Eucalllptus camaldulensis Dehnh (E rostrata Schlecht) rose (Rosa val unknown) l hyacinth (Eichhornia crassipes (Mart) Solms sedum (Sedum spectabile Boreau) ficus (Ficus elastica
~ Roxb ex Hornem) oleander (Nerium oleander L Ligustrum (Lig1lstrnm l1lcidum Ait) and crinum (Crinum fimbriat1llum Baker)
Differences in leaf mesophylls among the 11 plant genera (Hi) were compared with (1) Spectrophotometrically measured reshyflectance and transmittance and calculated absorptance values of the leaves over the 500- to 2500-nanometer (nm) 4 wavelength interval (2) percent leaf-water contents (oven-dry weight basis) (3) leaf-thickness measurements and (4) optical and geometrical leaf parameters
Percent leaf-water contents of the 11 plant genera ranged from nO percent for isolateral ~ (palisade layers on both sides) eucalypshytus to 95 percent for succulent sedum and begonia leaves with storage cells on each side of a central chlorenchyma
Dorsiventral rose and compact corn leaves (no palisade cells) were thinnest (about 015 mm) and succulent sedum leaves were thickest (about 082 mm)
Spectral data for upper (adaxial) and lower (abaxial) leaf surfaces of all genera for 550- 800- 1000- 1450- 1650- 1950- ann 2200-nm wavelengths were appended Spectra of upper leaf surfaces of oleander corn hyacinth and eucalyptus were charted At the 1000-nm wavelength diffuse reflectance was highest for dorsiventral oleander and lowest for compact corn leaves transmittance was lowest for oleander and highest for corn leaves and absorptance for corn and oleander leaves was approximately 3 and 9 percent respectively rhe compact corn leaf with low light reflectance and high transmittance has fewer intercellular air spaces than the dorsi ventral oleander leaf
Because the interaction of plant genera with wavelength was small mean spectral measurements of 550- 800- 1000- 1450- 1650- 1950- and 2200-nm wavelengths were compared Lower leaf surfaces of dorsi ventral leaves had higher reflectance values than upper leaf surfaces indicating that the spongy parenchyma contribute more to light scattering than the palisade parenchyma
bull Both nanometer (nm) and micron (p) are used here to denote spectral wavelengths A nanometer is one thousandth of a micron and a micron is one thousandth of a millimeter
bull Botanical terms are definpd in the Glossary of Terms p 58
6 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of the leaf mesophyll This was substantiated by equal reflectance values of upper and lower surfaces of compact corn leaves
Thick leaves of oleander crinum fi~us sedum and Iigustrum had the lowest percent transmittarce Mean spectrophotometrishycally measured transmittance values for the above wavelengths were lower when light was passed from the top through the leaves than when light was passed through from the bottom The difference jn transmittance was caused by greater light diffusion by upper leaf surfaces since the spectrophotometer used irradishyates the specimen with direct light
Diffuse reflectance data were made absolute by correcting for decay of the magnesium-oxide standard on the spectrophotomshyeter and absorptance was calculated as 100 - [percent reshyflectance + percent transmittance] When data for wavelengths were averaged highest absorptance values of 606 582 591 and 583 percent were obtained for the thick dorsiventral ficus crinum ligustrum and oleander leaves respectively and lowest values of 404 and 390 percent were obtained for the thin comshypact corn and thin dorsiventral rose leaves respectively
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1450 nm) regions respectively At the 550-nm wavelengths reflectance was greater from the lower surface than from the upper surface of dorsiventral leaves indicating that the chloroplasts in the palisade cells absorbed light Lower and upper surface reflectances were the same for the compact corn leaves Considering upper leaf surfaces only thick succulent sedum and thick ficus leaves had the highest and lowest reflecshytance values of 20 and 8 percent respectively
Percent transmittance was lowest for ficus and highest for succulent begonia leaves Compact leaves of corn and succulent leaves of sedum and begonia with essentially a continuous mesoshyphyll arrangement had the loyrest light absorptance of approxishymately 70 percent Thick dorsiventral leaves of ficus oleander and ligustrum with multiseriide epidermal layers or multishypalisade layers had the highest light absorptance of 80 to 90 percent
At the 1000-nm wavelength reflectance values from upper and lower leaf surface measurements were essentially alike Comshypact corn leaves had the lowest reflectance (43 percent) and succulent sedum and dorsi ventral ficus oleander ligustrum and crinum leaves had the highest reflectance (53 percent) The 350
7 LEAF MESOPHYLLS OF TWENTY CROPS
percent transmithnce of oleander leaves was lowest and 545 percent for corn was highest The thin corn and rose leaves had the lowest absorptance values (2 to 3 percent) and the thick leaves of ligustrum ficus crinum sed urn and oleander had the highest values (8 to 11 percent)
Correlation coefficients were considered that accounted for at least 60 percent of the variation (r2 x 100) between leaf thickness and reflectance leaf thickness and absorptance leaf-water conshytent and refiectance and leaf-water content and absorptance Oleander eucalyptus and hyacinth leaves gave the highest coshyefficients among the plant genera studied In general co~ efficients were negative between water content and reflectance and between thickness and reflectance measurements and middotvith the main exception of eucalyptus coefficients were positive beshytween leaf-water content and absorptance and between thickness and absorptance calculations at 1450- 1650- 1950- and 2200shynm wavelengths
Experimental values of leaf reflectance and transmittance for the 11 genera were transformed into effective optical constants Such optical constants are useful in the prediction of reflectance phenomena associated with leaves either stacked in a spectroshyphotometer or arranged naturally in a plant canopy The index of refraction n was plotted against wavelength to obtain disshypersion curves The absorption coefficient k was shown to be equivalent to values determined previously for leaves from agrishycultural crops
Each of the 11 genera has been analyzed to obtain geometrical parameters that specify the amount of water and air in the leaf The water parameter is the thickness of liquid water necessary to produce the observed leaf absorption Observed and computed valuesmiddot of leaf-water thickness were obtained Agreement was good except for ligustrum crinum and sedum The air paramshyeter is the number of identical compact layers into which the equivalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance
A third parameter infinite reflectance is observed when leaves are piled sufficiently deep Infinite reflectance was tabulated at L65 p for all 11 genera Infinite reflectance was shown to be a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed
The literatUre dealing with the interaction of light with plant leaves and leaf mesophyl1 structure is reviewed in the technical
8 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
monograph by Gausman and others (15) and is not repeated here Attention is directed however to the research of Aboukhaled 6 who related the optical properties of leaves to their energy-balance photosynthesis and water-use efficiency
Materials and Methods Twenty plant genera were selected that are presently economshy
ically important or have the potential of becoming valuable in the Texas Lower Rio Grande Valley Pigweed was considered here as a crop rather than a weed because it is used by some farmers as a plow-under or green-manure crop The leaves of A
the selected genera varied in mesophyll arrangement thickness water content and other structural differences such as palisadeshylayer arrangement Leaf characteristics of the 20 crops and the families they represent are indicated in table 1 and typical photomicrographs of leaf transections are depicted in figure 1
All plants were field grown in the summer of 1970 except that lettuce and onions were purchased fresh at a local market soybeans and beans were grown in a greenhouse and wheat was grown during the 1969 season
Ten mature and healthy-appearing leaves were sampled from each of the 20 plant genera Immediately after excision leaves were wrapped in Saran or Glad-Wrap to minimize dehydration Leaves were wiped with a slightly dampened cloth to remove surface contaminants before spectrophotometric measurements The tubular onion leaf was split longitudinally and only oneshyhalf was measured
A Beckman Model DK-2A spectrophotometer equipped with a reflectance attachment was used to measure spectral diffuse
bull Aboukhaled A Optical properties of leaves in relation to their energyshybalance photosynthesis and water use efficiency (PhD thesis) University of Calif Library Davis 139 pp 1966
7 Trade names are used in this pUblication solely for the purpose of providing specific information Mention of a trade name does not constitute a guarantee or warranty of the product by the US Department of Agriculture or an endorsement by the Department over other products not mentioned
FIGURE I-Photomicrographs of leaf transections of 20 plant genera differing in leaf thickness mesophyll arrangement and other gross structural characteristics A avocado S bean C cantaloup D corniE cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
9 LEAF MESOPHYLLS OF TWENTY CROPS
FIGURE I-Continued
10 TECHNICAL BULLETIN 1middot165 US DEPT OF AGRICULTURE
FIGURE I-Continued
LEAF MESOPHYLLS OF TWENTY CROPS 11
reflectance and transmittance on adaxial (uppel) surfaces of single leaves over the 500- to 2500-nm wavelength interval Data have 1ieen corrected for decay of the magnesium-oxide standard (27) to give absolute radiometric data Absorptance was calculated from the absolute values as Percent absorptance = 100 - (percent reflectance + percent transmittance)
Measurements of leaf thickness and diffuse reflectance and transmittance and fixation of tissue were completed within 6 hours after leaves were harvested or obtained for each genus
Leaf thickness was measured with a linear-displacement transshyducer and digital voltmeter (17) Leaf area was determined with a planimeter except that area per leaf of corn sorghum and sugarcane was calculated by the method of Slickter Wearden and Pauli (29) and area per leaf of cotton was calculated by Tohnsons method (20) Percent leaf-water content was detershymined on an oven-dry weight basis by drying at 68deg C for 72 hours and cooling in a desiccator before final weighing Leaf thickness and water-content determinations were not made on wheat leaves
Tissue pieces taken near the center of leaves approximately one-half inch on either side of the midrib were fixed in formalinshyacetic acid-alcohol dehydrated with a tertiary butanol series embedded in paraffin stained with either the safranin-fast green or the safranin-fast green-orange G combinations (19) and transversally microtomed at 12- or 14- thickness The relatively thick transverse sections were used to accentuate intercellular spaces and thus enhance differences in mesophyll arrangeshyments among the crops Photomicrographs were obtained with a Zeiss Standard Universal Photomicroscope
Spectrophotometrically measured reflectance and transmittance and calculated absorptance of seven wavelengths (550 800 1000 14)0 1650 1950 and 2200 nm) were analyzed for variance (W) Duncans Multiple Range Test (7) was used to test differshyences among means of the seven wavelengths at the 5-percent probability level Standard deviation was calculated to compare the leaf reflectance transmittance and absorptance of the crops at the 550- and 1000-nm wavelengths Coefficients were calcushylated to evaluate the correlation of leaf thickness with leaf-water content Coefficients were also obtained for correlations of reshyflectance transmittance and absorptance with grams of water per cubic centimeter of leaf tissue leaf-water content on an ovenshydry weight basis and leaf thickness Correlation coefficients of plusmn 0775 were chosen as levels of significance because they acshy
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
~ID~O~O~--~i500~I~__~W~~--~aoo
500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
100 10
TRAHSiMTlAHCE
20
i i
401 ~ 1 ~
O ~
70
SO ~ REFLpoundCT~ 00
o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
N
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
p
500 1000 -~------- ~o
100
140
~50 460 170 -j80
90
0 RJOO
o---middotiir-~LiOo----2000L---2100
R
IDO~ 100
TRANSMfTTANCE
i ~
A8SORPT~CE
~~ 1 80 j
III REFLpoundCTANC( 90
Dshy~
aa
T
o
o~
Q
70 i 60~
I
~ ~u 201shy
bull Ill
o~
s
1000
IOO
wlllVflfJrtGTH fWI)
--oDIGTl1
~o
REFUclANCE
FIGURE 2-Continued
_~
2DOO
(HOO __--J
Z300
2gt00
10
120 1 30
1 ~ ~o ~ 60
10
bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
4 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Sixteen of the 20 crops were analyzed to determine the thickshyness of water necessary to produce the observed leaf absorption and the number of identical compact layers into which the equivshyalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance Sugarcane corn sorghum and wheat leaves were not included because laborashytory determinations of thickness and water content were not made on entire leaves There was no statistically significant difshyference between observed and computed values for leaf water for 10 of the crops Pumpkin avocado okra tomato cantaloup and lettuce showed differences but they were not highly significant
The limiting value of reflectance from leaves piled sufficiently deep is termed infinite reflectance This parameter is a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed Infinite reflectance has been tabulated at 165 p for the 20 crops
Introduction To interpret remote-sensing data from aircraft and spacecraft
thE reflectance produced by features on the ~arths surface must be understood (33)3 The specific problem in agriculture is interpretation of reflectance produced by vegetation usuaIIy supershyimposed on a soil background Plant leaves yield most of the signal measured by remote sensors in aircraft a1 rl spacecraft Therefore they are of prime interest in characterizing vegetashytion and their interaction with electromagnetic radiation must be understood
The purpose of research reported here was to relate the leaf mesophyll structure of 20 important agricultural plant genera to their light spectra and to optical and geometrical parameters This report is a sequel to a technical monograph by Gausman and others (15) which presented research results on the spectralshyenergy relations of leaves for 11 plant genera characterized by marked differences in leaf-mesophyll arrangements The research was based on the hypothesis that leaf-mesophyll arrangements influence spectral-energy relations of leaves and plant canopies Previous research had considered only the relation of light reflecshytance to leaf surface morphologies (28) and to isobilateral leaves (18)
Plants studied were corn (Zea mays L) banana (Musa acuminata Colla (M cavendishii Lamb) I begonia (Begonia C1tshy
bull Italic numbers in partnthfSfR refer to Literature Cited p 43
LEAF MESOPHYLLS OF TWENTY CROPS 5
cullata Willd (E sernperlo1ens Link amp Otto) eucalyptus (Eucalllptus camaldulensis Dehnh (E rostrata Schlecht) rose (Rosa val unknown) l hyacinth (Eichhornia crassipes (Mart) Solms sedum (Sedum spectabile Boreau) ficus (Ficus elastica
~ Roxb ex Hornem) oleander (Nerium oleander L Ligustrum (Lig1lstrnm l1lcidum Ait) and crinum (Crinum fimbriat1llum Baker)
Differences in leaf mesophylls among the 11 plant genera (Hi) were compared with (1) Spectrophotometrically measured reshyflectance and transmittance and calculated absorptance values of the leaves over the 500- to 2500-nanometer (nm) 4 wavelength interval (2) percent leaf-water contents (oven-dry weight basis) (3) leaf-thickness measurements and (4) optical and geometrical leaf parameters
Percent leaf-water contents of the 11 plant genera ranged from nO percent for isolateral ~ (palisade layers on both sides) eucalypshytus to 95 percent for succulent sedum and begonia leaves with storage cells on each side of a central chlorenchyma
Dorsiventral rose and compact corn leaves (no palisade cells) were thinnest (about 015 mm) and succulent sedum leaves were thickest (about 082 mm)
Spectral data for upper (adaxial) and lower (abaxial) leaf surfaces of all genera for 550- 800- 1000- 1450- 1650- 1950- ann 2200-nm wavelengths were appended Spectra of upper leaf surfaces of oleander corn hyacinth and eucalyptus were charted At the 1000-nm wavelength diffuse reflectance was highest for dorsiventral oleander and lowest for compact corn leaves transmittance was lowest for oleander and highest for corn leaves and absorptance for corn and oleander leaves was approximately 3 and 9 percent respectively rhe compact corn leaf with low light reflectance and high transmittance has fewer intercellular air spaces than the dorsi ventral oleander leaf
Because the interaction of plant genera with wavelength was small mean spectral measurements of 550- 800- 1000- 1450- 1650- 1950- and 2200-nm wavelengths were compared Lower leaf surfaces of dorsi ventral leaves had higher reflectance values than upper leaf surfaces indicating that the spongy parenchyma contribute more to light scattering than the palisade parenchyma
bull Both nanometer (nm) and micron (p) are used here to denote spectral wavelengths A nanometer is one thousandth of a micron and a micron is one thousandth of a millimeter
bull Botanical terms are definpd in the Glossary of Terms p 58
6 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of the leaf mesophyll This was substantiated by equal reflectance values of upper and lower surfaces of compact corn leaves
Thick leaves of oleander crinum fi~us sedum and Iigustrum had the lowest percent transmittarce Mean spectrophotometrishycally measured transmittance values for the above wavelengths were lower when light was passed from the top through the leaves than when light was passed through from the bottom The difference jn transmittance was caused by greater light diffusion by upper leaf surfaces since the spectrophotometer used irradishyates the specimen with direct light
Diffuse reflectance data were made absolute by correcting for decay of the magnesium-oxide standard on the spectrophotomshyeter and absorptance was calculated as 100 - [percent reshyflectance + percent transmittance] When data for wavelengths were averaged highest absorptance values of 606 582 591 and 583 percent were obtained for the thick dorsiventral ficus crinum ligustrum and oleander leaves respectively and lowest values of 404 and 390 percent were obtained for the thin comshypact corn and thin dorsiventral rose leaves respectively
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1450 nm) regions respectively At the 550-nm wavelengths reflectance was greater from the lower surface than from the upper surface of dorsiventral leaves indicating that the chloroplasts in the palisade cells absorbed light Lower and upper surface reflectances were the same for the compact corn leaves Considering upper leaf surfaces only thick succulent sedum and thick ficus leaves had the highest and lowest reflecshytance values of 20 and 8 percent respectively
Percent transmittance was lowest for ficus and highest for succulent begonia leaves Compact leaves of corn and succulent leaves of sedum and begonia with essentially a continuous mesoshyphyll arrangement had the loyrest light absorptance of approxishymately 70 percent Thick dorsiventral leaves of ficus oleander and ligustrum with multiseriide epidermal layers or multishypalisade layers had the highest light absorptance of 80 to 90 percent
At the 1000-nm wavelength reflectance values from upper and lower leaf surface measurements were essentially alike Comshypact corn leaves had the lowest reflectance (43 percent) and succulent sedum and dorsi ventral ficus oleander ligustrum and crinum leaves had the highest reflectance (53 percent) The 350
7 LEAF MESOPHYLLS OF TWENTY CROPS
percent transmithnce of oleander leaves was lowest and 545 percent for corn was highest The thin corn and rose leaves had the lowest absorptance values (2 to 3 percent) and the thick leaves of ligustrum ficus crinum sed urn and oleander had the highest values (8 to 11 percent)
Correlation coefficients were considered that accounted for at least 60 percent of the variation (r2 x 100) between leaf thickness and reflectance leaf thickness and absorptance leaf-water conshytent and refiectance and leaf-water content and absorptance Oleander eucalyptus and hyacinth leaves gave the highest coshyefficients among the plant genera studied In general co~ efficients were negative between water content and reflectance and between thickness and reflectance measurements and middotvith the main exception of eucalyptus coefficients were positive beshytween leaf-water content and absorptance and between thickness and absorptance calculations at 1450- 1650- 1950- and 2200shynm wavelengths
Experimental values of leaf reflectance and transmittance for the 11 genera were transformed into effective optical constants Such optical constants are useful in the prediction of reflectance phenomena associated with leaves either stacked in a spectroshyphotometer or arranged naturally in a plant canopy The index of refraction n was plotted against wavelength to obtain disshypersion curves The absorption coefficient k was shown to be equivalent to values determined previously for leaves from agrishycultural crops
Each of the 11 genera has been analyzed to obtain geometrical parameters that specify the amount of water and air in the leaf The water parameter is the thickness of liquid water necessary to produce the observed leaf absorption Observed and computed valuesmiddot of leaf-water thickness were obtained Agreement was good except for ligustrum crinum and sedum The air paramshyeter is the number of identical compact layers into which the equivalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance
A third parameter infinite reflectance is observed when leaves are piled sufficiently deep Infinite reflectance was tabulated at L65 p for all 11 genera Infinite reflectance was shown to be a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed
The literatUre dealing with the interaction of light with plant leaves and leaf mesophyl1 structure is reviewed in the technical
8 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
monograph by Gausman and others (15) and is not repeated here Attention is directed however to the research of Aboukhaled 6 who related the optical properties of leaves to their energy-balance photosynthesis and water-use efficiency
Materials and Methods Twenty plant genera were selected that are presently economshy
ically important or have the potential of becoming valuable in the Texas Lower Rio Grande Valley Pigweed was considered here as a crop rather than a weed because it is used by some farmers as a plow-under or green-manure crop The leaves of A
the selected genera varied in mesophyll arrangement thickness water content and other structural differences such as palisadeshylayer arrangement Leaf characteristics of the 20 crops and the families they represent are indicated in table 1 and typical photomicrographs of leaf transections are depicted in figure 1
All plants were field grown in the summer of 1970 except that lettuce and onions were purchased fresh at a local market soybeans and beans were grown in a greenhouse and wheat was grown during the 1969 season
Ten mature and healthy-appearing leaves were sampled from each of the 20 plant genera Immediately after excision leaves were wrapped in Saran or Glad-Wrap to minimize dehydration Leaves were wiped with a slightly dampened cloth to remove surface contaminants before spectrophotometric measurements The tubular onion leaf was split longitudinally and only oneshyhalf was measured
A Beckman Model DK-2A spectrophotometer equipped with a reflectance attachment was used to measure spectral diffuse
bull Aboukhaled A Optical properties of leaves in relation to their energyshybalance photosynthesis and water use efficiency (PhD thesis) University of Calif Library Davis 139 pp 1966
7 Trade names are used in this pUblication solely for the purpose of providing specific information Mention of a trade name does not constitute a guarantee or warranty of the product by the US Department of Agriculture or an endorsement by the Department over other products not mentioned
FIGURE I-Photomicrographs of leaf transections of 20 plant genera differing in leaf thickness mesophyll arrangement and other gross structural characteristics A avocado S bean C cantaloup D corniE cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
9 LEAF MESOPHYLLS OF TWENTY CROPS
FIGURE I-Continued
10 TECHNICAL BULLETIN 1middot165 US DEPT OF AGRICULTURE
FIGURE I-Continued
LEAF MESOPHYLLS OF TWENTY CROPS 11
reflectance and transmittance on adaxial (uppel) surfaces of single leaves over the 500- to 2500-nm wavelength interval Data have 1ieen corrected for decay of the magnesium-oxide standard (27) to give absolute radiometric data Absorptance was calculated from the absolute values as Percent absorptance = 100 - (percent reflectance + percent transmittance)
Measurements of leaf thickness and diffuse reflectance and transmittance and fixation of tissue were completed within 6 hours after leaves were harvested or obtained for each genus
Leaf thickness was measured with a linear-displacement transshyducer and digital voltmeter (17) Leaf area was determined with a planimeter except that area per leaf of corn sorghum and sugarcane was calculated by the method of Slickter Wearden and Pauli (29) and area per leaf of cotton was calculated by Tohnsons method (20) Percent leaf-water content was detershymined on an oven-dry weight basis by drying at 68deg C for 72 hours and cooling in a desiccator before final weighing Leaf thickness and water-content determinations were not made on wheat leaves
Tissue pieces taken near the center of leaves approximately one-half inch on either side of the midrib were fixed in formalinshyacetic acid-alcohol dehydrated with a tertiary butanol series embedded in paraffin stained with either the safranin-fast green or the safranin-fast green-orange G combinations (19) and transversally microtomed at 12- or 14- thickness The relatively thick transverse sections were used to accentuate intercellular spaces and thus enhance differences in mesophyll arrangeshyments among the crops Photomicrographs were obtained with a Zeiss Standard Universal Photomicroscope
Spectrophotometrically measured reflectance and transmittance and calculated absorptance of seven wavelengths (550 800 1000 14)0 1650 1950 and 2200 nm) were analyzed for variance (W) Duncans Multiple Range Test (7) was used to test differshyences among means of the seven wavelengths at the 5-percent probability level Standard deviation was calculated to compare the leaf reflectance transmittance and absorptance of the crops at the 550- and 1000-nm wavelengths Coefficients were calcushylated to evaluate the correlation of leaf thickness with leaf-water content Coefficients were also obtained for correlations of reshyflectance transmittance and absorptance with grams of water per cubic centimeter of leaf tissue leaf-water content on an ovenshydry weight basis and leaf thickness Correlation coefficients of plusmn 0775 were chosen as levels of significance because they acshy
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
~ID~O~O~--~i500~I~__~W~~--~aoo
500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
100 10
TRAHSiMTlAHCE
20
i i
401 ~ 1 ~
O ~
70
SO ~ REFLpoundCT~ 00
o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
N
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
p
500 1000 -~------- ~o
100
140
~50 460 170 -j80
90
0 RJOO
o---middotiir-~LiOo----2000L---2100
R
IDO~ 100
TRANSMfTTANCE
i ~
A8SORPT~CE
~~ 1 80 j
III REFLpoundCTANC( 90
Dshy~
aa
T
o
o~
Q
70 i 60~
I
~ ~u 201shy
bull Ill
o~
s
1000
IOO
wlllVflfJrtGTH fWI)
--oDIGTl1
~o
REFUclANCE
FIGURE 2-Continued
_~
2DOO
(HOO __--J
Z300
2gt00
10
120 1 30
1 ~ ~o ~ 60
10
bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
LEAF MESOPHYLLS OF TWENTY CROPS 5
cullata Willd (E sernperlo1ens Link amp Otto) eucalyptus (Eucalllptus camaldulensis Dehnh (E rostrata Schlecht) rose (Rosa val unknown) l hyacinth (Eichhornia crassipes (Mart) Solms sedum (Sedum spectabile Boreau) ficus (Ficus elastica
~ Roxb ex Hornem) oleander (Nerium oleander L Ligustrum (Lig1lstrnm l1lcidum Ait) and crinum (Crinum fimbriat1llum Baker)
Differences in leaf mesophylls among the 11 plant genera (Hi) were compared with (1) Spectrophotometrically measured reshyflectance and transmittance and calculated absorptance values of the leaves over the 500- to 2500-nanometer (nm) 4 wavelength interval (2) percent leaf-water contents (oven-dry weight basis) (3) leaf-thickness measurements and (4) optical and geometrical leaf parameters
Percent leaf-water contents of the 11 plant genera ranged from nO percent for isolateral ~ (palisade layers on both sides) eucalypshytus to 95 percent for succulent sedum and begonia leaves with storage cells on each side of a central chlorenchyma
Dorsiventral rose and compact corn leaves (no palisade cells) were thinnest (about 015 mm) and succulent sedum leaves were thickest (about 082 mm)
Spectral data for upper (adaxial) and lower (abaxial) leaf surfaces of all genera for 550- 800- 1000- 1450- 1650- 1950- ann 2200-nm wavelengths were appended Spectra of upper leaf surfaces of oleander corn hyacinth and eucalyptus were charted At the 1000-nm wavelength diffuse reflectance was highest for dorsiventral oleander and lowest for compact corn leaves transmittance was lowest for oleander and highest for corn leaves and absorptance for corn and oleander leaves was approximately 3 and 9 percent respectively rhe compact corn leaf with low light reflectance and high transmittance has fewer intercellular air spaces than the dorsi ventral oleander leaf
Because the interaction of plant genera with wavelength was small mean spectral measurements of 550- 800- 1000- 1450- 1650- 1950- and 2200-nm wavelengths were compared Lower leaf surfaces of dorsi ventral leaves had higher reflectance values than upper leaf surfaces indicating that the spongy parenchyma contribute more to light scattering than the palisade parenchyma
bull Both nanometer (nm) and micron (p) are used here to denote spectral wavelengths A nanometer is one thousandth of a micron and a micron is one thousandth of a millimeter
bull Botanical terms are definpd in the Glossary of Terms p 58
6 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of the leaf mesophyll This was substantiated by equal reflectance values of upper and lower surfaces of compact corn leaves
Thick leaves of oleander crinum fi~us sedum and Iigustrum had the lowest percent transmittarce Mean spectrophotometrishycally measured transmittance values for the above wavelengths were lower when light was passed from the top through the leaves than when light was passed through from the bottom The difference jn transmittance was caused by greater light diffusion by upper leaf surfaces since the spectrophotometer used irradishyates the specimen with direct light
Diffuse reflectance data were made absolute by correcting for decay of the magnesium-oxide standard on the spectrophotomshyeter and absorptance was calculated as 100 - [percent reshyflectance + percent transmittance] When data for wavelengths were averaged highest absorptance values of 606 582 591 and 583 percent were obtained for the thick dorsiventral ficus crinum ligustrum and oleander leaves respectively and lowest values of 404 and 390 percent were obtained for the thin comshypact corn and thin dorsiventral rose leaves respectively
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1450 nm) regions respectively At the 550-nm wavelengths reflectance was greater from the lower surface than from the upper surface of dorsiventral leaves indicating that the chloroplasts in the palisade cells absorbed light Lower and upper surface reflectances were the same for the compact corn leaves Considering upper leaf surfaces only thick succulent sedum and thick ficus leaves had the highest and lowest reflecshytance values of 20 and 8 percent respectively
Percent transmittance was lowest for ficus and highest for succulent begonia leaves Compact leaves of corn and succulent leaves of sedum and begonia with essentially a continuous mesoshyphyll arrangement had the loyrest light absorptance of approxishymately 70 percent Thick dorsiventral leaves of ficus oleander and ligustrum with multiseriide epidermal layers or multishypalisade layers had the highest light absorptance of 80 to 90 percent
At the 1000-nm wavelength reflectance values from upper and lower leaf surface measurements were essentially alike Comshypact corn leaves had the lowest reflectance (43 percent) and succulent sedum and dorsi ventral ficus oleander ligustrum and crinum leaves had the highest reflectance (53 percent) The 350
7 LEAF MESOPHYLLS OF TWENTY CROPS
percent transmithnce of oleander leaves was lowest and 545 percent for corn was highest The thin corn and rose leaves had the lowest absorptance values (2 to 3 percent) and the thick leaves of ligustrum ficus crinum sed urn and oleander had the highest values (8 to 11 percent)
Correlation coefficients were considered that accounted for at least 60 percent of the variation (r2 x 100) between leaf thickness and reflectance leaf thickness and absorptance leaf-water conshytent and refiectance and leaf-water content and absorptance Oleander eucalyptus and hyacinth leaves gave the highest coshyefficients among the plant genera studied In general co~ efficients were negative between water content and reflectance and between thickness and reflectance measurements and middotvith the main exception of eucalyptus coefficients were positive beshytween leaf-water content and absorptance and between thickness and absorptance calculations at 1450- 1650- 1950- and 2200shynm wavelengths
Experimental values of leaf reflectance and transmittance for the 11 genera were transformed into effective optical constants Such optical constants are useful in the prediction of reflectance phenomena associated with leaves either stacked in a spectroshyphotometer or arranged naturally in a plant canopy The index of refraction n was plotted against wavelength to obtain disshypersion curves The absorption coefficient k was shown to be equivalent to values determined previously for leaves from agrishycultural crops
Each of the 11 genera has been analyzed to obtain geometrical parameters that specify the amount of water and air in the leaf The water parameter is the thickness of liquid water necessary to produce the observed leaf absorption Observed and computed valuesmiddot of leaf-water thickness were obtained Agreement was good except for ligustrum crinum and sedum The air paramshyeter is the number of identical compact layers into which the equivalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance
A third parameter infinite reflectance is observed when leaves are piled sufficiently deep Infinite reflectance was tabulated at L65 p for all 11 genera Infinite reflectance was shown to be a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed
The literatUre dealing with the interaction of light with plant leaves and leaf mesophyl1 structure is reviewed in the technical
8 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
monograph by Gausman and others (15) and is not repeated here Attention is directed however to the research of Aboukhaled 6 who related the optical properties of leaves to their energy-balance photosynthesis and water-use efficiency
Materials and Methods Twenty plant genera were selected that are presently economshy
ically important or have the potential of becoming valuable in the Texas Lower Rio Grande Valley Pigweed was considered here as a crop rather than a weed because it is used by some farmers as a plow-under or green-manure crop The leaves of A
the selected genera varied in mesophyll arrangement thickness water content and other structural differences such as palisadeshylayer arrangement Leaf characteristics of the 20 crops and the families they represent are indicated in table 1 and typical photomicrographs of leaf transections are depicted in figure 1
All plants were field grown in the summer of 1970 except that lettuce and onions were purchased fresh at a local market soybeans and beans were grown in a greenhouse and wheat was grown during the 1969 season
Ten mature and healthy-appearing leaves were sampled from each of the 20 plant genera Immediately after excision leaves were wrapped in Saran or Glad-Wrap to minimize dehydration Leaves were wiped with a slightly dampened cloth to remove surface contaminants before spectrophotometric measurements The tubular onion leaf was split longitudinally and only oneshyhalf was measured
A Beckman Model DK-2A spectrophotometer equipped with a reflectance attachment was used to measure spectral diffuse
bull Aboukhaled A Optical properties of leaves in relation to their energyshybalance photosynthesis and water use efficiency (PhD thesis) University of Calif Library Davis 139 pp 1966
7 Trade names are used in this pUblication solely for the purpose of providing specific information Mention of a trade name does not constitute a guarantee or warranty of the product by the US Department of Agriculture or an endorsement by the Department over other products not mentioned
FIGURE I-Photomicrographs of leaf transections of 20 plant genera differing in leaf thickness mesophyll arrangement and other gross structural characteristics A avocado S bean C cantaloup D corniE cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
9 LEAF MESOPHYLLS OF TWENTY CROPS
FIGURE I-Continued
10 TECHNICAL BULLETIN 1middot165 US DEPT OF AGRICULTURE
FIGURE I-Continued
LEAF MESOPHYLLS OF TWENTY CROPS 11
reflectance and transmittance on adaxial (uppel) surfaces of single leaves over the 500- to 2500-nm wavelength interval Data have 1ieen corrected for decay of the magnesium-oxide standard (27) to give absolute radiometric data Absorptance was calculated from the absolute values as Percent absorptance = 100 - (percent reflectance + percent transmittance)
Measurements of leaf thickness and diffuse reflectance and transmittance and fixation of tissue were completed within 6 hours after leaves were harvested or obtained for each genus
Leaf thickness was measured with a linear-displacement transshyducer and digital voltmeter (17) Leaf area was determined with a planimeter except that area per leaf of corn sorghum and sugarcane was calculated by the method of Slickter Wearden and Pauli (29) and area per leaf of cotton was calculated by Tohnsons method (20) Percent leaf-water content was detershymined on an oven-dry weight basis by drying at 68deg C for 72 hours and cooling in a desiccator before final weighing Leaf thickness and water-content determinations were not made on wheat leaves
Tissue pieces taken near the center of leaves approximately one-half inch on either side of the midrib were fixed in formalinshyacetic acid-alcohol dehydrated with a tertiary butanol series embedded in paraffin stained with either the safranin-fast green or the safranin-fast green-orange G combinations (19) and transversally microtomed at 12- or 14- thickness The relatively thick transverse sections were used to accentuate intercellular spaces and thus enhance differences in mesophyll arrangeshyments among the crops Photomicrographs were obtained with a Zeiss Standard Universal Photomicroscope
Spectrophotometrically measured reflectance and transmittance and calculated absorptance of seven wavelengths (550 800 1000 14)0 1650 1950 and 2200 nm) were analyzed for variance (W) Duncans Multiple Range Test (7) was used to test differshyences among means of the seven wavelengths at the 5-percent probability level Standard deviation was calculated to compare the leaf reflectance transmittance and absorptance of the crops at the 550- and 1000-nm wavelengths Coefficients were calcushylated to evaluate the correlation of leaf thickness with leaf-water content Coefficients were also obtained for correlations of reshyflectance transmittance and absorptance with grams of water per cubic centimeter of leaf tissue leaf-water content on an ovenshydry weight basis and leaf thickness Correlation coefficients of plusmn 0775 were chosen as levels of significance because they acshy
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
~ID~O~O~--~i500~I~__~W~~--~aoo
500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
100 10
TRAHSiMTlAHCE
20
i i
401 ~ 1 ~
O ~
70
SO ~ REFLpoundCT~ 00
o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
N
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
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TRANSMfTTANCE
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III REFLpoundCTANC( 90
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bull Ill
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REFUclANCE
FIGURE 2-Continued
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120 1 30
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bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
6 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of the leaf mesophyll This was substantiated by equal reflectance values of upper and lower surfaces of compact corn leaves
Thick leaves of oleander crinum fi~us sedum and Iigustrum had the lowest percent transmittarce Mean spectrophotometrishycally measured transmittance values for the above wavelengths were lower when light was passed from the top through the leaves than when light was passed through from the bottom The difference jn transmittance was caused by greater light diffusion by upper leaf surfaces since the spectrophotometer used irradishyates the specimen with direct light
Diffuse reflectance data were made absolute by correcting for decay of the magnesium-oxide standard on the spectrophotomshyeter and absorptance was calculated as 100 - [percent reshyflectance + percent transmittance] When data for wavelengths were averaged highest absorptance values of 606 582 591 and 583 percent were obtained for the thick dorsiventral ficus crinum ligustrum and oleander leaves respectively and lowest values of 404 and 390 percent were obtained for the thin comshypact corn and thin dorsiventral rose leaves respectively
Intensive study was given to the 550- and 1000-nm waveshylengths representing the visible (400 to 750 nm) and nearshyinfrared (750 to 1450 nm) regions respectively At the 550-nm wavelengths reflectance was greater from the lower surface than from the upper surface of dorsiventral leaves indicating that the chloroplasts in the palisade cells absorbed light Lower and upper surface reflectances were the same for the compact corn leaves Considering upper leaf surfaces only thick succulent sedum and thick ficus leaves had the highest and lowest reflecshytance values of 20 and 8 percent respectively
Percent transmittance was lowest for ficus and highest for succulent begonia leaves Compact leaves of corn and succulent leaves of sedum and begonia with essentially a continuous mesoshyphyll arrangement had the loyrest light absorptance of approxishymately 70 percent Thick dorsiventral leaves of ficus oleander and ligustrum with multiseriide epidermal layers or multishypalisade layers had the highest light absorptance of 80 to 90 percent
At the 1000-nm wavelength reflectance values from upper and lower leaf surface measurements were essentially alike Comshypact corn leaves had the lowest reflectance (43 percent) and succulent sedum and dorsi ventral ficus oleander ligustrum and crinum leaves had the highest reflectance (53 percent) The 350
7 LEAF MESOPHYLLS OF TWENTY CROPS
percent transmithnce of oleander leaves was lowest and 545 percent for corn was highest The thin corn and rose leaves had the lowest absorptance values (2 to 3 percent) and the thick leaves of ligustrum ficus crinum sed urn and oleander had the highest values (8 to 11 percent)
Correlation coefficients were considered that accounted for at least 60 percent of the variation (r2 x 100) between leaf thickness and reflectance leaf thickness and absorptance leaf-water conshytent and refiectance and leaf-water content and absorptance Oleander eucalyptus and hyacinth leaves gave the highest coshyefficients among the plant genera studied In general co~ efficients were negative between water content and reflectance and between thickness and reflectance measurements and middotvith the main exception of eucalyptus coefficients were positive beshytween leaf-water content and absorptance and between thickness and absorptance calculations at 1450- 1650- 1950- and 2200shynm wavelengths
Experimental values of leaf reflectance and transmittance for the 11 genera were transformed into effective optical constants Such optical constants are useful in the prediction of reflectance phenomena associated with leaves either stacked in a spectroshyphotometer or arranged naturally in a plant canopy The index of refraction n was plotted against wavelength to obtain disshypersion curves The absorption coefficient k was shown to be equivalent to values determined previously for leaves from agrishycultural crops
Each of the 11 genera has been analyzed to obtain geometrical parameters that specify the amount of water and air in the leaf The water parameter is the thickness of liquid water necessary to produce the observed leaf absorption Observed and computed valuesmiddot of leaf-water thickness were obtained Agreement was good except for ligustrum crinum and sedum The air paramshyeter is the number of identical compact layers into which the equivalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance
A third parameter infinite reflectance is observed when leaves are piled sufficiently deep Infinite reflectance was tabulated at L65 p for all 11 genera Infinite reflectance was shown to be a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed
The literatUre dealing with the interaction of light with plant leaves and leaf mesophyl1 structure is reviewed in the technical
8 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
monograph by Gausman and others (15) and is not repeated here Attention is directed however to the research of Aboukhaled 6 who related the optical properties of leaves to their energy-balance photosynthesis and water-use efficiency
Materials and Methods Twenty plant genera were selected that are presently economshy
ically important or have the potential of becoming valuable in the Texas Lower Rio Grande Valley Pigweed was considered here as a crop rather than a weed because it is used by some farmers as a plow-under or green-manure crop The leaves of A
the selected genera varied in mesophyll arrangement thickness water content and other structural differences such as palisadeshylayer arrangement Leaf characteristics of the 20 crops and the families they represent are indicated in table 1 and typical photomicrographs of leaf transections are depicted in figure 1
All plants were field grown in the summer of 1970 except that lettuce and onions were purchased fresh at a local market soybeans and beans were grown in a greenhouse and wheat was grown during the 1969 season
Ten mature and healthy-appearing leaves were sampled from each of the 20 plant genera Immediately after excision leaves were wrapped in Saran or Glad-Wrap to minimize dehydration Leaves were wiped with a slightly dampened cloth to remove surface contaminants before spectrophotometric measurements The tubular onion leaf was split longitudinally and only oneshyhalf was measured
A Beckman Model DK-2A spectrophotometer equipped with a reflectance attachment was used to measure spectral diffuse
bull Aboukhaled A Optical properties of leaves in relation to their energyshybalance photosynthesis and water use efficiency (PhD thesis) University of Calif Library Davis 139 pp 1966
7 Trade names are used in this pUblication solely for the purpose of providing specific information Mention of a trade name does not constitute a guarantee or warranty of the product by the US Department of Agriculture or an endorsement by the Department over other products not mentioned
FIGURE I-Photomicrographs of leaf transections of 20 plant genera differing in leaf thickness mesophyll arrangement and other gross structural characteristics A avocado S bean C cantaloup D corniE cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
9 LEAF MESOPHYLLS OF TWENTY CROPS
FIGURE I-Continued
10 TECHNICAL BULLETIN 1middot165 US DEPT OF AGRICULTURE
FIGURE I-Continued
LEAF MESOPHYLLS OF TWENTY CROPS 11
reflectance and transmittance on adaxial (uppel) surfaces of single leaves over the 500- to 2500-nm wavelength interval Data have 1ieen corrected for decay of the magnesium-oxide standard (27) to give absolute radiometric data Absorptance was calculated from the absolute values as Percent absorptance = 100 - (percent reflectance + percent transmittance)
Measurements of leaf thickness and diffuse reflectance and transmittance and fixation of tissue were completed within 6 hours after leaves were harvested or obtained for each genus
Leaf thickness was measured with a linear-displacement transshyducer and digital voltmeter (17) Leaf area was determined with a planimeter except that area per leaf of corn sorghum and sugarcane was calculated by the method of Slickter Wearden and Pauli (29) and area per leaf of cotton was calculated by Tohnsons method (20) Percent leaf-water content was detershymined on an oven-dry weight basis by drying at 68deg C for 72 hours and cooling in a desiccator before final weighing Leaf thickness and water-content determinations were not made on wheat leaves
Tissue pieces taken near the center of leaves approximately one-half inch on either side of the midrib were fixed in formalinshyacetic acid-alcohol dehydrated with a tertiary butanol series embedded in paraffin stained with either the safranin-fast green or the safranin-fast green-orange G combinations (19) and transversally microtomed at 12- or 14- thickness The relatively thick transverse sections were used to accentuate intercellular spaces and thus enhance differences in mesophyll arrangeshyments among the crops Photomicrographs were obtained with a Zeiss Standard Universal Photomicroscope
Spectrophotometrically measured reflectance and transmittance and calculated absorptance of seven wavelengths (550 800 1000 14)0 1650 1950 and 2200 nm) were analyzed for variance (W) Duncans Multiple Range Test (7) was used to test differshyences among means of the seven wavelengths at the 5-percent probability level Standard deviation was calculated to compare the leaf reflectance transmittance and absorptance of the crops at the 550- and 1000-nm wavelengths Coefficients were calcushylated to evaluate the correlation of leaf thickness with leaf-water content Coefficients were also obtained for correlations of reshyflectance transmittance and absorptance with grams of water per cubic centimeter of leaf tissue leaf-water content on an ovenshydry weight basis and leaf thickness Correlation coefficients of plusmn 0775 were chosen as levels of significance because they acshy
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
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~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
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WAVELENGTH )
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FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
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17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
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REFUCTANCE
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18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
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LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
7 LEAF MESOPHYLLS OF TWENTY CROPS
percent transmithnce of oleander leaves was lowest and 545 percent for corn was highest The thin corn and rose leaves had the lowest absorptance values (2 to 3 percent) and the thick leaves of ligustrum ficus crinum sed urn and oleander had the highest values (8 to 11 percent)
Correlation coefficients were considered that accounted for at least 60 percent of the variation (r2 x 100) between leaf thickness and reflectance leaf thickness and absorptance leaf-water conshytent and refiectance and leaf-water content and absorptance Oleander eucalyptus and hyacinth leaves gave the highest coshyefficients among the plant genera studied In general co~ efficients were negative between water content and reflectance and between thickness and reflectance measurements and middotvith the main exception of eucalyptus coefficients were positive beshytween leaf-water content and absorptance and between thickness and absorptance calculations at 1450- 1650- 1950- and 2200shynm wavelengths
Experimental values of leaf reflectance and transmittance for the 11 genera were transformed into effective optical constants Such optical constants are useful in the prediction of reflectance phenomena associated with leaves either stacked in a spectroshyphotometer or arranged naturally in a plant canopy The index of refraction n was plotted against wavelength to obtain disshypersion curves The absorption coefficient k was shown to be equivalent to values determined previously for leaves from agrishycultural crops
Each of the 11 genera has been analyzed to obtain geometrical parameters that specify the amount of water and air in the leaf The water parameter is the thickness of liquid water necessary to produce the observed leaf absorption Observed and computed valuesmiddot of leaf-water thickness were obtained Agreement was good except for ligustrum crinum and sedum The air paramshyeter is the number of identical compact layers into which the equivalent water must be subdivided to achieve the observed partition of light between reflectance and transmittance
A third parameter infinite reflectance is observed when leaves are piled sufficiently deep Infinite reflectance was tabulated at L65 p for all 11 genera Infinite reflectance was shown to be a function of the calculated thickness of the identical compact layers of which a leaf is assumed to be composed
The literatUre dealing with the interaction of light with plant leaves and leaf mesophyl1 structure is reviewed in the technical
8 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
monograph by Gausman and others (15) and is not repeated here Attention is directed however to the research of Aboukhaled 6 who related the optical properties of leaves to their energy-balance photosynthesis and water-use efficiency
Materials and Methods Twenty plant genera were selected that are presently economshy
ically important or have the potential of becoming valuable in the Texas Lower Rio Grande Valley Pigweed was considered here as a crop rather than a weed because it is used by some farmers as a plow-under or green-manure crop The leaves of A
the selected genera varied in mesophyll arrangement thickness water content and other structural differences such as palisadeshylayer arrangement Leaf characteristics of the 20 crops and the families they represent are indicated in table 1 and typical photomicrographs of leaf transections are depicted in figure 1
All plants were field grown in the summer of 1970 except that lettuce and onions were purchased fresh at a local market soybeans and beans were grown in a greenhouse and wheat was grown during the 1969 season
Ten mature and healthy-appearing leaves were sampled from each of the 20 plant genera Immediately after excision leaves were wrapped in Saran or Glad-Wrap to minimize dehydration Leaves were wiped with a slightly dampened cloth to remove surface contaminants before spectrophotometric measurements The tubular onion leaf was split longitudinally and only oneshyhalf was measured
A Beckman Model DK-2A spectrophotometer equipped with a reflectance attachment was used to measure spectral diffuse
bull Aboukhaled A Optical properties of leaves in relation to their energyshybalance photosynthesis and water use efficiency (PhD thesis) University of Calif Library Davis 139 pp 1966
7 Trade names are used in this pUblication solely for the purpose of providing specific information Mention of a trade name does not constitute a guarantee or warranty of the product by the US Department of Agriculture or an endorsement by the Department over other products not mentioned
FIGURE I-Photomicrographs of leaf transections of 20 plant genera differing in leaf thickness mesophyll arrangement and other gross structural characteristics A avocado S bean C cantaloup D corniE cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
9 LEAF MESOPHYLLS OF TWENTY CROPS
FIGURE I-Continued
10 TECHNICAL BULLETIN 1middot165 US DEPT OF AGRICULTURE
FIGURE I-Continued
LEAF MESOPHYLLS OF TWENTY CROPS 11
reflectance and transmittance on adaxial (uppel) surfaces of single leaves over the 500- to 2500-nm wavelength interval Data have 1ieen corrected for decay of the magnesium-oxide standard (27) to give absolute radiometric data Absorptance was calculated from the absolute values as Percent absorptance = 100 - (percent reflectance + percent transmittance)
Measurements of leaf thickness and diffuse reflectance and transmittance and fixation of tissue were completed within 6 hours after leaves were harvested or obtained for each genus
Leaf thickness was measured with a linear-displacement transshyducer and digital voltmeter (17) Leaf area was determined with a planimeter except that area per leaf of corn sorghum and sugarcane was calculated by the method of Slickter Wearden and Pauli (29) and area per leaf of cotton was calculated by Tohnsons method (20) Percent leaf-water content was detershymined on an oven-dry weight basis by drying at 68deg C for 72 hours and cooling in a desiccator before final weighing Leaf thickness and water-content determinations were not made on wheat leaves
Tissue pieces taken near the center of leaves approximately one-half inch on either side of the midrib were fixed in formalinshyacetic acid-alcohol dehydrated with a tertiary butanol series embedded in paraffin stained with either the safranin-fast green or the safranin-fast green-orange G combinations (19) and transversally microtomed at 12- or 14- thickness The relatively thick transverse sections were used to accentuate intercellular spaces and thus enhance differences in mesophyll arrangeshyments among the crops Photomicrographs were obtained with a Zeiss Standard Universal Photomicroscope
Spectrophotometrically measured reflectance and transmittance and calculated absorptance of seven wavelengths (550 800 1000 14)0 1650 1950 and 2200 nm) were analyzed for variance (W) Duncans Multiple Range Test (7) was used to test differshyences among means of the seven wavelengths at the 5-percent probability level Standard deviation was calculated to compare the leaf reflectance transmittance and absorptance of the crops at the 550- and 1000-nm wavelengths Coefficients were calcushylated to evaluate the correlation of leaf thickness with leaf-water content Coefficients were also obtained for correlations of reshyflectance transmittance and absorptance with grams of water per cubic centimeter of leaf tissue leaf-water content on an ovenshydry weight basis and leaf thickness Correlation coefficients of plusmn 0775 were chosen as levels of significance because they acshy
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
~ID~O~O~--~i500~I~__~W~~--~aoo
500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
100 10
TRAHSiMTlAHCE
20
i i
401 ~ 1 ~
O ~
70
SO ~ REFLpoundCT~ 00
o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
N
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
p
500 1000 -~------- ~o
100
140
~50 460 170 -j80
90
0 RJOO
o---middotiir-~LiOo----2000L---2100
R
IDO~ 100
TRANSMfTTANCE
i ~
A8SORPT~CE
~~ 1 80 j
III REFLpoundCTANC( 90
Dshy~
aa
T
o
o~
Q
70 i 60~
I
~ ~u 201shy
bull Ill
o~
s
1000
IOO
wlllVflfJrtGTH fWI)
--oDIGTl1
~o
REFUclANCE
FIGURE 2-Continued
_~
2DOO
(HOO __--J
Z300
2gt00
10
120 1 30
1 ~ ~o ~ 60
10
bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
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(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
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New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
8 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
monograph by Gausman and others (15) and is not repeated here Attention is directed however to the research of Aboukhaled 6 who related the optical properties of leaves to their energy-balance photosynthesis and water-use efficiency
Materials and Methods Twenty plant genera were selected that are presently economshy
ically important or have the potential of becoming valuable in the Texas Lower Rio Grande Valley Pigweed was considered here as a crop rather than a weed because it is used by some farmers as a plow-under or green-manure crop The leaves of A
the selected genera varied in mesophyll arrangement thickness water content and other structural differences such as palisadeshylayer arrangement Leaf characteristics of the 20 crops and the families they represent are indicated in table 1 and typical photomicrographs of leaf transections are depicted in figure 1
All plants were field grown in the summer of 1970 except that lettuce and onions were purchased fresh at a local market soybeans and beans were grown in a greenhouse and wheat was grown during the 1969 season
Ten mature and healthy-appearing leaves were sampled from each of the 20 plant genera Immediately after excision leaves were wrapped in Saran or Glad-Wrap to minimize dehydration Leaves were wiped with a slightly dampened cloth to remove surface contaminants before spectrophotometric measurements The tubular onion leaf was split longitudinally and only oneshyhalf was measured
A Beckman Model DK-2A spectrophotometer equipped with a reflectance attachment was used to measure spectral diffuse
bull Aboukhaled A Optical properties of leaves in relation to their energyshybalance photosynthesis and water use efficiency (PhD thesis) University of Calif Library Davis 139 pp 1966
7 Trade names are used in this pUblication solely for the purpose of providing specific information Mention of a trade name does not constitute a guarantee or warranty of the product by the US Department of Agriculture or an endorsement by the Department over other products not mentioned
FIGURE I-Photomicrographs of leaf transections of 20 plant genera differing in leaf thickness mesophyll arrangement and other gross structural characteristics A avocado S bean C cantaloup D corniE cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
9 LEAF MESOPHYLLS OF TWENTY CROPS
FIGURE I-Continued
10 TECHNICAL BULLETIN 1middot165 US DEPT OF AGRICULTURE
FIGURE I-Continued
LEAF MESOPHYLLS OF TWENTY CROPS 11
reflectance and transmittance on adaxial (uppel) surfaces of single leaves over the 500- to 2500-nm wavelength interval Data have 1ieen corrected for decay of the magnesium-oxide standard (27) to give absolute radiometric data Absorptance was calculated from the absolute values as Percent absorptance = 100 - (percent reflectance + percent transmittance)
Measurements of leaf thickness and diffuse reflectance and transmittance and fixation of tissue were completed within 6 hours after leaves were harvested or obtained for each genus
Leaf thickness was measured with a linear-displacement transshyducer and digital voltmeter (17) Leaf area was determined with a planimeter except that area per leaf of corn sorghum and sugarcane was calculated by the method of Slickter Wearden and Pauli (29) and area per leaf of cotton was calculated by Tohnsons method (20) Percent leaf-water content was detershymined on an oven-dry weight basis by drying at 68deg C for 72 hours and cooling in a desiccator before final weighing Leaf thickness and water-content determinations were not made on wheat leaves
Tissue pieces taken near the center of leaves approximately one-half inch on either side of the midrib were fixed in formalinshyacetic acid-alcohol dehydrated with a tertiary butanol series embedded in paraffin stained with either the safranin-fast green or the safranin-fast green-orange G combinations (19) and transversally microtomed at 12- or 14- thickness The relatively thick transverse sections were used to accentuate intercellular spaces and thus enhance differences in mesophyll arrangeshyments among the crops Photomicrographs were obtained with a Zeiss Standard Universal Photomicroscope
Spectrophotometrically measured reflectance and transmittance and calculated absorptance of seven wavelengths (550 800 1000 14)0 1650 1950 and 2200 nm) were analyzed for variance (W) Duncans Multiple Range Test (7) was used to test differshyences among means of the seven wavelengths at the 5-percent probability level Standard deviation was calculated to compare the leaf reflectance transmittance and absorptance of the crops at the 550- and 1000-nm wavelengths Coefficients were calcushylated to evaluate the correlation of leaf thickness with leaf-water content Coefficients were also obtained for correlations of reshyflectance transmittance and absorptance with grams of water per cubic centimeter of leaf tissue leaf-water content on an ovenshydry weight basis and leaf thickness Correlation coefficients of plusmn 0775 were chosen as levels of significance because they acshy
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
~ID~O~O~--~i500~I~__~W~~--~aoo
500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
100 10
TRAHSiMTlAHCE
20
i i
401 ~ 1 ~
O ~
70
SO ~ REFLpoundCT~ 00
o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
N
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
p
500 1000 -~------- ~o
100
140
~50 460 170 -j80
90
0 RJOO
o---middotiir-~LiOo----2000L---2100
R
IDO~ 100
TRANSMfTTANCE
i ~
A8SORPT~CE
~~ 1 80 j
III REFLpoundCTANC( 90
Dshy~
aa
T
o
o~
Q
70 i 60~
I
~ ~u 201shy
bull Ill
o~
s
1000
IOO
wlllVflfJrtGTH fWI)
--oDIGTl1
~o
REFUclANCE
FIGURE 2-Continued
_~
2DOO
(HOO __--J
Z300
2gt00
10
120 1 30
1 ~ ~o ~ 60
10
bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
9 LEAF MESOPHYLLS OF TWENTY CROPS
FIGURE I-Continued
10 TECHNICAL BULLETIN 1middot165 US DEPT OF AGRICULTURE
FIGURE I-Continued
LEAF MESOPHYLLS OF TWENTY CROPS 11
reflectance and transmittance on adaxial (uppel) surfaces of single leaves over the 500- to 2500-nm wavelength interval Data have 1ieen corrected for decay of the magnesium-oxide standard (27) to give absolute radiometric data Absorptance was calculated from the absolute values as Percent absorptance = 100 - (percent reflectance + percent transmittance)
Measurements of leaf thickness and diffuse reflectance and transmittance and fixation of tissue were completed within 6 hours after leaves were harvested or obtained for each genus
Leaf thickness was measured with a linear-displacement transshyducer and digital voltmeter (17) Leaf area was determined with a planimeter except that area per leaf of corn sorghum and sugarcane was calculated by the method of Slickter Wearden and Pauli (29) and area per leaf of cotton was calculated by Tohnsons method (20) Percent leaf-water content was detershymined on an oven-dry weight basis by drying at 68deg C for 72 hours and cooling in a desiccator before final weighing Leaf thickness and water-content determinations were not made on wheat leaves
Tissue pieces taken near the center of leaves approximately one-half inch on either side of the midrib were fixed in formalinshyacetic acid-alcohol dehydrated with a tertiary butanol series embedded in paraffin stained with either the safranin-fast green or the safranin-fast green-orange G combinations (19) and transversally microtomed at 12- or 14- thickness The relatively thick transverse sections were used to accentuate intercellular spaces and thus enhance differences in mesophyll arrangeshyments among the crops Photomicrographs were obtained with a Zeiss Standard Universal Photomicroscope
Spectrophotometrically measured reflectance and transmittance and calculated absorptance of seven wavelengths (550 800 1000 14)0 1650 1950 and 2200 nm) were analyzed for variance (W) Duncans Multiple Range Test (7) was used to test differshyences among means of the seven wavelengths at the 5-percent probability level Standard deviation was calculated to compare the leaf reflectance transmittance and absorptance of the crops at the 550- and 1000-nm wavelengths Coefficients were calcushylated to evaluate the correlation of leaf thickness with leaf-water content Coefficients were also obtained for correlations of reshyflectance transmittance and absorptance with grams of water per cubic centimeter of leaf tissue leaf-water content on an ovenshydry weight basis and leaf thickness Correlation coefficients of plusmn 0775 were chosen as levels of significance because they acshy
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
~ID~O~O~--~i500~I~__~W~~--~aoo
500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
100 10
TRAHSiMTlAHCE
20
i i
401 ~ 1 ~
O ~
70
SO ~ REFLpoundCT~ 00
o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
N
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
p
500 1000 -~------- ~o
100
140
~50 460 170 -j80
90
0 RJOO
o---middotiir-~LiOo----2000L---2100
R
IDO~ 100
TRANSMfTTANCE
i ~
A8SORPT~CE
~~ 1 80 j
III REFLpoundCTANC( 90
Dshy~
aa
T
o
o~
Q
70 i 60~
I
~ ~u 201shy
bull Ill
o~
s
1000
IOO
wlllVflfJrtGTH fWI)
--oDIGTl1
~o
REFUclANCE
FIGURE 2-Continued
_~
2DOO
(HOO __--J
Z300
2gt00
10
120 1 30
1 ~ ~o ~ 60
10
bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
10 TECHNICAL BULLETIN 1middot165 US DEPT OF AGRICULTURE
FIGURE I-Continued
LEAF MESOPHYLLS OF TWENTY CROPS 11
reflectance and transmittance on adaxial (uppel) surfaces of single leaves over the 500- to 2500-nm wavelength interval Data have 1ieen corrected for decay of the magnesium-oxide standard (27) to give absolute radiometric data Absorptance was calculated from the absolute values as Percent absorptance = 100 - (percent reflectance + percent transmittance)
Measurements of leaf thickness and diffuse reflectance and transmittance and fixation of tissue were completed within 6 hours after leaves were harvested or obtained for each genus
Leaf thickness was measured with a linear-displacement transshyducer and digital voltmeter (17) Leaf area was determined with a planimeter except that area per leaf of corn sorghum and sugarcane was calculated by the method of Slickter Wearden and Pauli (29) and area per leaf of cotton was calculated by Tohnsons method (20) Percent leaf-water content was detershymined on an oven-dry weight basis by drying at 68deg C for 72 hours and cooling in a desiccator before final weighing Leaf thickness and water-content determinations were not made on wheat leaves
Tissue pieces taken near the center of leaves approximately one-half inch on either side of the midrib were fixed in formalinshyacetic acid-alcohol dehydrated with a tertiary butanol series embedded in paraffin stained with either the safranin-fast green or the safranin-fast green-orange G combinations (19) and transversally microtomed at 12- or 14- thickness The relatively thick transverse sections were used to accentuate intercellular spaces and thus enhance differences in mesophyll arrangeshyments among the crops Photomicrographs were obtained with a Zeiss Standard Universal Photomicroscope
Spectrophotometrically measured reflectance and transmittance and calculated absorptance of seven wavelengths (550 800 1000 14)0 1650 1950 and 2200 nm) were analyzed for variance (W) Duncans Multiple Range Test (7) was used to test differshyences among means of the seven wavelengths at the 5-percent probability level Standard deviation was calculated to compare the leaf reflectance transmittance and absorptance of the crops at the 550- and 1000-nm wavelengths Coefficients were calcushylated to evaluate the correlation of leaf thickness with leaf-water content Coefficients were also obtained for correlations of reshyflectance transmittance and absorptance with grams of water per cubic centimeter of leaf tissue leaf-water content on an ovenshydry weight basis and leaf thickness Correlation coefficients of plusmn 0775 were chosen as levels of significance because they acshy
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
~ID~O~O~--~i500~I~__~W~~--~aoo
500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
100 10
TRAHSiMTlAHCE
20
i i
401 ~ 1 ~
O ~
70
SO ~ REFLpoundCT~ 00
o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
N
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
p
500 1000 -~------- ~o
100
140
~50 460 170 -j80
90
0 RJOO
o---middotiir-~LiOo----2000L---2100
R
IDO~ 100
TRANSMfTTANCE
i ~
A8SORPT~CE
~~ 1 80 j
III REFLpoundCTANC( 90
Dshy~
aa
T
o
o~
Q
70 i 60~
I
~ ~u 201shy
bull Ill
o~
s
1000
IOO
wlllVflfJrtGTH fWI)
--oDIGTl1
~o
REFUclANCE
FIGURE 2-Continued
_~
2DOO
(HOO __--J
Z300
2gt00
10
120 1 30
1 ~ ~o ~ 60
10
bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
LEAF MESOPHYLLS OF TWENTY CROPS 11
reflectance and transmittance on adaxial (uppel) surfaces of single leaves over the 500- to 2500-nm wavelength interval Data have 1ieen corrected for decay of the magnesium-oxide standard (27) to give absolute radiometric data Absorptance was calculated from the absolute values as Percent absorptance = 100 - (percent reflectance + percent transmittance)
Measurements of leaf thickness and diffuse reflectance and transmittance and fixation of tissue were completed within 6 hours after leaves were harvested or obtained for each genus
Leaf thickness was measured with a linear-displacement transshyducer and digital voltmeter (17) Leaf area was determined with a planimeter except that area per leaf of corn sorghum and sugarcane was calculated by the method of Slickter Wearden and Pauli (29) and area per leaf of cotton was calculated by Tohnsons method (20) Percent leaf-water content was detershymined on an oven-dry weight basis by drying at 68deg C for 72 hours and cooling in a desiccator before final weighing Leaf thickness and water-content determinations were not made on wheat leaves
Tissue pieces taken near the center of leaves approximately one-half inch on either side of the midrib were fixed in formalinshyacetic acid-alcohol dehydrated with a tertiary butanol series embedded in paraffin stained with either the safranin-fast green or the safranin-fast green-orange G combinations (19) and transversally microtomed at 12- or 14- thickness The relatively thick transverse sections were used to accentuate intercellular spaces and thus enhance differences in mesophyll arrangeshyments among the crops Photomicrographs were obtained with a Zeiss Standard Universal Photomicroscope
Spectrophotometrically measured reflectance and transmittance and calculated absorptance of seven wavelengths (550 800 1000 14)0 1650 1950 and 2200 nm) were analyzed for variance (W) Duncans Multiple Range Test (7) was used to test differshyences among means of the seven wavelengths at the 5-percent probability level Standard deviation was calculated to compare the leaf reflectance transmittance and absorptance of the crops at the 550- and 1000-nm wavelengths Coefficients were calcushylated to evaluate the correlation of leaf thickness with leaf-water content Coefficients were also obtained for correlations of reshyflectance transmittance and absorptance with grams of water per cubic centimeter of leaf tissue leaf-water content on an ovenshydry weight basis and leaf thickness Correlation coefficients of plusmn 0775 were chosen as levels of significance because they acshy
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
~ID~O~O~--~i500~I~__~W~~--~aoo
500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
100 10
TRAHSiMTlAHCE
20
i i
401 ~ 1 ~
O ~
70
SO ~ REFLpoundCT~ 00
o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
N
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
p
500 1000 -~------- ~o
100
140
~50 460 170 -j80
90
0 RJOO
o---middotiir-~LiOo----2000L---2100
R
IDO~ 100
TRANSMfTTANCE
i ~
A8SORPT~CE
~~ 1 80 j
III REFLpoundCTANC( 90
Dshy~
aa
T
o
o~
Q
70 i 60~
I
~ ~u 201shy
bull Ill
o~
s
1000
IOO
wlllVflfJrtGTH fWI)
--oDIGTl1
~o
REFUclANCE
FIGURE 2-Continued
_~
2DOO
(HOO __--J
Z300
2gt00
10
120 1 30
1 ~ ~o ~ 60
10
bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
TABLE l-Common scientific and family names leaf mesophyll arrangements and structural characterisshy l
Common name I
Avocado
Bean Cantaloup
Corn
Cotton
Lettuce Okra
Onion Orange
Peach __
Pepper
Pigweed
tics of plant leaves used in this study ~ Mesophyll Additional structural Q
Scientific name Family name arrangement characteristics bull I1 Z
Persea americana Mill Lauraceae Dorsiventral ___ _ _ _ _ Thick cuticle multiple palisade layers long and narrow pali shy
Q
~ sade cells
Phaseolu~ vUlgarn L Legurninosae _ Dorsiyentral Very porous mesophyll Xl
Cucmnis mew L var Cucurbitaceae Dorsiventral Multiple palisade layers hairs cantalupensis Naud lower epidermis sect
Zeamays L Gramineae Compact Bulliform cells hairs upper Z epidermis
Gos8Jjpium hirsutum L Malvaceae Dorsiventral Glandular hairs nectaries lyshy en en
sigenous glands
Lactuca sativa L Compollitae Compact Large cells porous mesophyll C in
Hibis~ esculentus L Malvaceae Dorsiventral Well-differentiated porous meshysophyll tl ~
~
Allium cepa L Amaryllidacea-~ _ Dorsiventral Tubular leaves ~
Cit~ sinensis (L) Osbeck Rutaceae _ Dorsiventral Thick cuticle with wax layers o multiple palisade layers lyshy j
sigenous cavities gt Prunus persica (L) Batsch Rosaceae ______ _ _ Dorsiventral lIfultiple palisade layers porshy ~
ous mesophyll Q
flCapsicurn annuurn L and other Solanaceae Dorsiventral Druse crystals spp
Amaranthus retrolexus L Amaranthaceae __ Compact Druse crystals veins surshy ~ rounded by large cubical pashyrenchymatous cells
tshy
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
~ID~O~O~--~i500~I~__~W~~--~aoo
500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
100 10
TRAHSiMTlAHCE
20
i i
401 ~ 1 ~
O ~
70
SO ~ REFLpoundCT~ 00
o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
N
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
p
500 1000 -~------- ~o
100
140
~50 460 170 -j80
90
0 RJOO
o---middotiir-~LiOo----2000L---2100
R
IDO~ 100
TRANSMfTTANCE
i ~
A8SORPT~CE
~~ 1 80 j
III REFLpoundCTANC( 90
Dshy~
aa
T
o
o~
Q
70 i 60~
I
~ ~u 201shy
bull Ill
o~
s
1000
IOO
wlllVflfJrtGTH fWI)
--oDIGTl1
~o
REFUclANCE
FIGURE 2-Continued
_~
2DOO
(HOO __--J
Z300
2gt00
10
120 1 30
1 ~ ~o ~ 60
10
bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
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bull ~
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44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
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(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
Pumpkin Cucurbita pepo L Cucurbitilceae Dorsiventral Multiple palisade layers hairs upper and lower epidermis
Sorghum Sorghum bicolor (L) Moench laquolaquolaquo ___ laquo Gramineae Compact Bulliform cells Soybean _laquo Glycine mlUl (L) Merr___ bull _ _ Legumino8ae laquo_ Dorsiventral Porous mesophyll Sugarcane _____ Saccharum oficinarum L Gramineae Compact BuIliform cells laquolaquolaquo
Sunflower Helianthus annuus L CompoBitae Isolateral _ _ Hairs upper and lower epishydermis
Tomato _laquo ___ laquo Lycoperlticon esculentum Mill Dorsi ven tral Hairs upper and lower epishy eSolanaceae dermis glandular hairs lower asurface tzj
Watermelon CitruUus lanatus (Thunb CIlCucurbitaceae Dorsiventral Multiple palisade layers glanshy o Mansf ddular hairs lower surface lI
Wheat _________ Triticum aestivum L _ laquo _Gramineae _ bull Compact BuIliform cells ~
t bull Generic names used as common names are not italicized or capitalized in the text CIl
bull Names are those formerly used by New Crops Research Branch ARS USDA Beltsville o l
bull Arbitrary definitions of mesophyll arrangements used herein are Dorsiventral a usually porous (many intercellular air spaces) mesophyll with palisade parenchyma cells in its upper part and spongy parenchyma cells in its lower part compact
I
mesophyll with little intercellular air space and no differentiation into palisade and spongy parenchyma cells isolateral a ~ Zporons mesophyll that tends to have long narrow cells throughout ~ bull Definitions are given in the Glossary of Terms p 58 References used were Esau (8) Fahn (9) Hayward (16) and Metcalfe
and Chalk (29) ~ o d CIl
~
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
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~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
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WAVELENGTH )
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FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
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17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
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REFUCTANCE
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18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
14 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
count for 60 percent of the variation (r2 x 100) between two series of variates This is often referred to as the biological level of significance
Results and Discussion Mature leaves were used because leaf age affects spectralshy
energy relations leaf-water contents and leaf thicknesses (13) The influence of leaf maturation on reflectance and transmitshy
tance is associated with compactness of internal cellular strucshyture Differences in cellular compactness of cotton leaves sampled from fourth or fifth nodes down from plant apexes affected reflectance of near-infrared light over the 750- to 1350-nm waveshylength intervals (12 14) Reflectance of older leaves was inshycreased because of an increase in intercellular air spaces Scattershying of light within leaves occurs most frequently at interfaces between cell walls (hydrated cellulose) and air cavities which have refractive indexes of 14 and 10 respectively (3231)
Very immature cells in young leaves are primarily protoplasmic with little vacuolate cell-sap storage (8 9 22) During cell growth (extension) cell water-filled vacuoles develop which usually coalesce to form a central sap cavity and the protoplasm covers the cell wall in a thin layer Hydrated leaves compared with dehydrated leaves reflected less and absorbed more light over the 500- to 2500-nm wavelength interval (1)
To facilitate interpretation the 500- to 2500-nm wavelength interval has been subdivided into three intervals (modified after Thomas Wiegand and Myers (31) (1) the visible-light absorpshytance region 500 to 750 nm dominated by pigments (primarily chlorophylls a and b carotene and xanthophylIs) (2) the nearshyinfrared region 750 to 1350 nm a region of high reflectance and low absorptance considerably affected by internal leaf strucshyture and (3) the 1350- to 2500-nm wavelength interval a reshygion influenced to some degree by leaf structure but greatly afshyfected by the amount of water in tissue-strong water-absorption bands occur at 1450 and 1950 nm Data for reflectance transshymittance and absorptance (representing means of 10 replications of each of 20 crops) for the 41 wavelengths are given in tables 12 13 and 14 (Appendix) Reflectance transmittance and abshysorptance spectra for the 20 crops are charted in figure 2
Leaf water and thickness
Figure 3 depicts the leaf-water contents of 19 crops (wheat not included) on a dry-weight basis Thick succulent lettuce
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
~ID~O~O~--~i500~I~__~W~~--~aoo
500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
100 10
TRAHSiMTlAHCE
20
i i
401 ~ 1 ~
O ~
70
SO ~ REFLpoundCT~ 00
o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
N
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
p
500 1000 -~------- ~o
100
140
~50 460 170 -j80
90
0 RJOO
o---middotiir-~LiOo----2000L---2100
R
IDO~ 100
TRANSMfTTANCE
i ~
A8SORPT~CE
~~ 1 80 j
III REFLpoundCTANC( 90
Dshy~
aa
T
o
o~
Q
70 i 60~
I
~ ~u 201shy
bull Ill
o~
s
1000
IOO
wlllVflfJrtGTH fWI)
--oDIGTl1
~o
REFUclANCE
FIGURE 2-Continued
_~
2DOO
(HOO __--J
Z300
2gt00
10
120 1 30
1 ~ ~o ~ 60
10
bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
15 LEAF MESOPHYLLS OF TWENTY CROPS
A
~~~_~-r0-100shy
70~
I- ~ ~~ 0i gtltgt~ A8SOI~ 1 ~
rtfY middotmiddotW~ 00~~ 1
to j REfLECiuGpound 90
0 D-JIOO ~~-___~_ ~-O-~~
~ lOOO ~oo 2000 2500
c
0 JO
ol L-~ l__ - ~o 1000
E
s
10lshyl
6O~
~ rmiddot~~Rm~
20~ 180 ON ~90REf1EcTANCpound
0 CIOO ------- ~ -~---------- -~-~
500 1000 ~ 2000 ~oo
o
lO~~~_~~o
60 1~O 0
~ ABSORPTANCE 450 ~ ~ ~ro ~
30 170
ot EFlEeTCE~ FoO
~~~-----~ zJoo -gt~oo
WAVELENGTH )
f
FIGURE 2-Light reflectance transmittance and absorptance spectra of the leaves of 20 crops for the 500- to 2500-nm wavelength interval A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed 111 pumpkin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watershymelon and T wheat
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
~ID~O~O~--~i500~I~__~W~~--~aoo
500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
100 10
TRAHSiMTlAHCE
20
i i
401 ~ 1 ~
O ~
70
SO ~ REFLpoundCT~ 00
o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
N
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
p
500 1000 -~------- ~o
100
140
~50 460 170 -j80
90
0 RJOO
o---middotiir-~LiOo----2000L---2100
R
IDO~ 100
TRANSMfTTANCE
i ~
A8SORPT~CE
~~ 1 80 j
III REFLpoundCTANC( 90
Dshy~
aa
T
o
o~
Q
70 i 60~
I
~ ~u 201shy
bull Ill
o~
s
1000
IOO
wlllVflfJrtGTH fWI)
--oDIGTl1
~o
REFUclANCE
FIGURE 2-Continued
_~
2DOO
(HOO __--J
Z300
2gt00
10
120 1 30
1 ~ ~o ~ 60
10
bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
16 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE 1000 1500 2000 2500
I I -------
90 TRUACl f ~ ~ )~ ]~
1000 i500 1
REFlECTAHCE
oL ljIOO
~~----~ooo~~--~I500~~--~~~~o----oo
-LDIGTgtt too)
20
10
o ~~O~-~IO~~~O~_~~~~lo~__~~~~----~aoo
IC
90
o H~IOO
-----JD=bo~- -0O_-WOOt- -----tOO WAyenELENG1H 111)M
FIGURE 2-Continued
~f ~ j~ IABSORPTANCE
~~ ro
W~ ~
IO~ REFUCTANCE ~ __ ~ 190
oL -- -11001-- ~ __ t--__~____ ___ -L-~
500 tOoo ~oo 2000 2500
H 1000 000 ~O
I I
1I 0
TRANSMITTAHa 10
TO
Or ~ o~ ~ 40~
JO~ 20~ 10 ~J REftECTANCE
oL ---~
00 1000 2gt00
J ZD~ _lt_~oo
~o
10 -i20 i30
70 0
~ ~~
oL lJOO
~ID~O~O~--~i500~I~__~W~~--~aoo
500 1000 000 ZDoo ~oo r-----r-----~- ~----r--------
100 10
TRAHSiMTlAHCE
20
i i
401 ~ 1 ~
O ~
70
SO ~ REFLpoundCT~ 00
o N 100 soT--middotiOtcf-middotmiddotmiddot-_middot 15OO----2Qooi----aoo
N
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
p
500 1000 -~------- ~o
100
140
~50 460 170 -j80
90
0 RJOO
o---middotiir-~LiOo----2000L---2100
R
IDO~ 100
TRANSMfTTANCE
i ~
A8SORPT~CE
~~ 1 80 j
III REFLpoundCTANC( 90
Dshy~
aa
T
o
o~
Q
70 i 60~
I
~ ~u 201shy
bull Ill
o~
s
1000
IOO
wlllVflfJrtGTH fWI)
--oDIGTl1
~o
REFUclANCE
FIGURE 2-Continued
_~
2DOO
(HOO __--J
Z300
2gt00
10
120 1 30
1 ~ ~o ~ 60
10
bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
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OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
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(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
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New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
17 LEAF MESOPHYLLS OF TWENTY CROPS
1000 ~oo 2000 ~ o
vM~ A8SORPTANCE - 4~
REFUCTANCE
ol ~ooomiddot~~-----~-~------~----~
PIOO--- -_~~--- 00 1300 2000 2500
p
500 1000 -~------- ~o
100
140
~50 460 170 -j80
90
0 RJOO
o---middotiir-~LiOo----2000L---2100
R
IDO~ 100
TRANSMfTTANCE
i ~
A8SORPT~CE
~~ 1 80 j
III REFLpoundCTANC( 90
Dshy~
aa
T
o
o~
Q
70 i 60~
I
~ ~u 201shy
bull Ill
o~
s
1000
IOO
wlllVflfJrtGTH fWI)
--oDIGTl1
~o
REFUclANCE
FIGURE 2-Continued
_~
2DOO
(HOO __--J
Z300
2gt00
10
120 1 30
1 ~ ~o ~ 60
10
bull 80
90
000 o
2gt00
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
18 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
leaves had significantly the highest water content of 970 percent The significantly lowest water contents were in avocado orange peach and sugarcane leaves (606 to 724 percent) which as a group were statistically alike (Duncans Test) Okra soybean pigweed cotton and watermelon leaves had essentially the same water contents 80( to 824 percent Four other groups with similar water contents within each group were corn and sorghum sunflower and pumpkin pepper and cantaloup and bean and onion In some leaves results show no apparent association of leaf-mesophyll arrangement with leaf-water content For example dorsi ventral leaves had both high (bean and onion) and low (avocado and orange) leaf-water contents However compact corn sorghum and sugarcane leaves within the family Gramineae and dorsiventral cotton and okra leaves within the family Malshyvaceae had quite similar water contents
Figure 4 portrays leaf thicknesses of 19 crops (wheat not inshycluded) Sunflower cantaloup lettuce and onion leaves were thickest (0407 to 0978 mm) and soybean peach pumpkin and
A
z g a
gt zw w
a 3 w u
Cgt J w lttZ 0 Z 5 a I- z 0
Z a ~ I- Ii a z ltt Ishya ~ ltgt 0 g W ltt z w0 a 0 0 ~ a u III 0 J 100 f- shy
~ z (J w 90 I- shy0 W f Ishyz 80 I- shyw I-Z 0 U
0 70 f- shyw Ishy
~ I
lL 60 l- shye W J
1 10
PLANT GENERA
FIGURE 3-Percent leaf-water content on an oven-dry weight basis of 19 crops (wheat excluded) arranged in ascending order of water content
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
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919 874 833 818 838 877 915 941 949 950 0 ll
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683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
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542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
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58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
19 LEAF MESOPHYLLS OF TWENTY CROPS
0 r 0 ca z 0 u laquo z Q I- laquo z zlaquo 0 a Q I- 0 laquo Q 0 0 Q u
0 ~ Ii 0 z
10 Q u
E SOe (I) (I) ILl Z I u 60 J l shylL ltl ILl 40 oJ
20
PLANT GENERA
FIGURE 4-Leaf thickness of 19 crops (wheat excluded) arranged in ascending order of thickness
pigweed leaves were thinnest (0140 to 0170 mm) compared with the other crop leaves Other groups with statistically alike leaf thicknesses were Pigweed okra corn pepper (0170 to 0203 mm) okra corn pepper cotton watermelon (0198 to 0232 mm) watermelon orange sugarcane avocado tomato and bean (0232 to 0263 mm) and orange sugarcane avocado toshymato bean and sorghum (0245 to 0274 mm) Within the famshyilies Malvaceae and Gramineae cotton and okra and sugarcane and sorghum respectively were alike in leaf thickness
Correlations of leaf thickness with water content of 19 crops were made (wheat not included) Highest coefficients obtained were 058 058 057 and 056 for avocado orange tomato and sorghum leaves respectively accounting for only 31 to 34 percent (r2 x 100) of the variation between leaf thicklesses and leafshywater contents Remaining coefficients with respective crops were Peach -051 lettuce 050 bean 050 cotton 048 watermelon 045 corn 043 soybean 042 pepper 041 pigshyweed 040 sugarcane 036 sunflower 030 cantaloup 029
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
20 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
pumpkin 020 okra 005 and onion 003 Thus leaf thickness and water content of leaves are poorly correlated There is no reason however why leaf thickness should be correlated with water content unless the ratio of water-storage cells to nonshywater-storage cells differs This could feasibly be true of succulent leaves
Spectrophotometric measurements for seven selected wavelengths
To reduce the enormous amount of spectrophotometrically genshyerated data and facilitate interpretation seven wavelengths were selected from the 41 wavelengths measured at 50-nm increments over the 500- to 2500-nm wavelength interval Wavelengths seshylected were 550 800 1000 1450 1650 1950 and 2200 nm representing respectively the visible region the beginning of the near-infrared plateau a wavelength on the near-infrared plateau the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band the 1950-nm A
water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band
The means of the seven wavelengths wiII be briefly discussed followed by an introduction to leaf spectra over the 500- to 2500-nm wavelength interval using the complementary 550- and 1000-nm wavelength data The 550-nm wavelength data will be used to assess relative differences in chlorophyll concentrations of the crop leaves and the 1000-nm wavelength data wi1l be used to evaluate the influence of leaf mesophyll arrangements on light reflectance
Table 2 presents the means of the selected seven wavelengths for the reflectance transmittance and absorptance by leaves of the 20 crops Considering reflectance onion had the lowest (181) and bean leaves the highest (316) percent reflectance Groups that had like but intermediate levels of reflectance were sunshyflower pigweed and cotton pigweed cotton and tomato cotton tomato sugarcane and cantaloup
Statistically orange leaves had the lowest transmittance (204) and soybean leaves had the highest (349) percent Three groups each alike in transmittance were wheat cantaloup sunshyflower and avocado (256 to 263) pepper sugarcane watershymelon and okra (271 to 279) and corn peach and pumpkin (300 to 306 percent)
Among the 20 crops onion leaves had the significantly highest absorptance of 574 and sorghum and soybean leaves as a group had the lowest absorptance (367 to 369) percent Other groups
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
bull ~
TABLE 2-Average percent reflectance trensmittance and absorptance of light of seven wavelengths (550 800 1000 1~50 1650 1950 and 2200 nm) by 10 leaves of each of 20 crops
Crop Reflectance 1 Crop Transmittance 1 Crop Absorptance 1
Percent Percent Percent Onion __________ 181a Orange __ _____ 204a Sorghum _ ____ 367a Lettuce ________ 206 b Bean - _______ 229 b Soybean __ __ _ 369a Sunflower ______ 248 Tomato __ ____ 230 b Peach ____ __397 b ~ c Pigweed _ _ _ ___ 249 cd Onion __ _____ 245 c Pumpkin _ 429 c
l
cdeCotton ___ _____ 253 Wheat _ _____ 256 d Corn _ _ _____ 436 cd is t1
Tomato _______ 254 de Cantaloup ___ 257 d Pigweed _bull ___ 437 cd CIl
Sugarcane __ _255 e Sunflower _ ____261 d Pepper _______ 441 de ~ Cantaloup _ 255 e Avocado _ _ 263 de Wheat _ ______ 445 de II
4 _
Watermelon 262 f Pepper _____ 271 ef Okra _ _ ___ 448 ef4 ___ ~ Corn _ _ _ _ ____ 264 f Sugarcane _____ 273 f Bean _ ___ _bull 455 fg CIl
Pumpkin _ ___ 265 f Watermelon ___ 274 f Cotton bull ___ __ 456 fg o l
Avocado ______ 270 g Okra ___ bull 279 f Watermelon __ 464 gh 8Okra _________ 273 g Cotton _ ___ 291 g Avocado _ 466 h
Soybean _______ 282 h Lettuce ___ 292 g Sugarcane bull A71 h ~ ZPepper ____ bull __ 289 Corn ___ bull ____ 300 h Orange ___ _ _A88
Peach _______ 298 j Peach ____ ____ 305 h Cantaloup _____ 488 ~ Wheat _ ___ 299 j Pumpkin _____ 306 h Sunflower _ __ 492 ~ Sorghum _______ 302 j Pigweed ___ bull ___314 Lettuce _ _ _ 502 j o
o-cOrange _ ____ 308 k Sorghum _ _____ 331 j Tomato _ __ bull516 k CIl
Bean _ _bull ____ 316 I Soybean ____ _ 349 k Onion __ __ __574 I
1 Values within columns followed by the same letter do not differ significantly at the 5-percent level using Duncans Multiple Range Test
~ 1-4
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
22 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
of crops that had like absorptances were Pumpkin corn and pigweed corgt pigweed pepper and wheat pepper wheat and okra okra bean and cotton bean cotton and watermelon and watermelon avocado and sugarcane
Leaf spectra of four selected crops
Reflectance and transmittance spectra (500- to 2500-nm) of four selected crops (bean avocado sorghum pigweed) are illusshytrated and compared in figures 5 and 6
Average reflectances at the 500-nm wavelength were 185 124 172 and 89 percent (table 3) for bean pigweed sorghum and avocado leaves respectively High reflectances indicate low conshycentrations of chlorophylls and conversely low reflectances inshydicate high concentrations
At the 1000-nm wavelength representing the 750- to 1350shynm near-infrared wavelength interval reflectances were 562 497 451 and 470 percent (table 4) for bean avocado pigweed and sorghum leaves respectively The dorsiventral bean and
100
__BEAN90 AVOCADO ______ SORGHUM
_____ PIGWEED80
P 70z 41 ()a 6041 et 41 () 50 z ~ () 40 41 J lJ 41 30 a
20
o 500 lOOO 1500 2000 2P00
bull WAVELENGTH Olm)
FIGURE 5-Reflectance spectra of leave of four crops Pigweed and sorghum leaves have compact mesophyllsi bean and avocado leaves have dorsishyventral mesophylls
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
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OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
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(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
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New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
23 LEAF MESOPHYLLS OF TWENTY CROPS
100
__BEAN90 _ __AVOCADO
______ SORGHUM ______ PIGWEED80
P z 141 70 Ua 141 e 60 141 U z 50 ~ Ishy 40E en z ~ 30a Ishy
20
10
0 I
500 lOOO l500 2000 2500
WAVELENGTH Qlm)
FIGURE G-Transmittance spectra of leaves of four crops Pigweed and sorghum leaves have compact mesophylIs bean and avocado leaves have dorsiventral mesophylls
avocado leaves with porous mesophylls had higher reflectances than the relatively compact pigweed and sorghum leaves This aspect will be discussed later
Transmittance curves were similar in shtlpe to the reflectance curves (fig 5 and 6) At the 550-nm wavelength transmittances were 109 95 90 and 41 percent for bean pigweed sorghum and avocado leaves respectively At the 1000-nm wavelength transmittances were 420 461 524 and 503 percent for bean avocado pigweed and sorghum leaves respectively
Calculated absorptances at the 550-nm wavelength were 706 782738 and 870 percent (table 3) for bean pigweed sorghum and avocado leaves respectively In the near-infrared (1000shynm) region absorptances were 18 25 27 and 42 percent for bean pigweed sorghum and avocado leaves respectively
)
Spectrophotometric measurements at the 550-nm wavelength
Intensive study was given to the 550- and 1OOO-nm waveshylength representing the visible (400 to 750 nm) and nearshy
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
1
24 TECHNICAL BULLETIN 1465 us DEPT OF AGRICULTURE
TABLE 3-Reflectance transnLittance and absorptance of light at the 550-nm wavelength by leaves of 20 crops
Transmittance Crop 1 AbsorptanceCrop Reflectance Crop PercentPercent Percent
Orange 19 Lettuce 254Avocado 89 Orange 102 Avocado 41 Sugarcane 692
Peach 109 Tomato 55 Onion 697 706Tomato 110 Wheat 58 Bean
62 Pepper 706Sunflower 110 Peach Onion 110 Cantaloup 87 Soybean 713
Pumpkin 118 Pumpkin 88 Okra 722
Sorghum SorghumCotton 118 90 738
Pigweed 124 Sunflower 91 Corn 740
Cantaloup 127 Pigweed 95 Cotton 751
Okra 129 Watermelon 96 Watermelon 759 Soybean 131 Corn 98 Pigweed 782
109 Cantaloup 786Wheat 134 Bean Watermelon 144 Sugarcane 122 Pumpkin 795
Corn 162 Pepper 126 Sunflower 799
Pepper 168 Cotton 131 Wheat 807 148 Peach 829Sorghum 172 Okra
Bean 185 Soybean 156 Tomato 836 188 Avocado 870Sugarcane 186 Onion
879Lettuce 443Lettuce 303 Orange 98 769Mean 2 133
Standard deviation 2 28~ 42 58
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
bull Lettuce was omitted because leaves were found to be immature
infrared (750 to 1350 nm) spectral regions respectively Tables 3 and 4 present light reflectance transmittance and absorptance values for the 550- and 1000-nm wavelength respectively
Mature healthy leaves have approximately equal reflectance and transmittance Lettuce leaves became suspect when it was noted that they had 353 percent reflectance and 537 percent transmittance at the 1000-nm wavelength (table 4) Investigashytion revealed that fourth leaves in from the exterior of the lettuce heads were used These leaves were not mature It is characteristic of immature leaves to have a high light transmittance and low reflectance (13) Therefore means and their standard deviations for the data in tables 3 and 4 were calculated omitting the data for lettuce leaves
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
LEAF MESOPHYLLS OF TWENTY CROPS 25
The mean reflectance of crop leaves at the 550-nm wavelength was 133 percent plusmn 28 percent (one standard deviation) AlI crops fell within the 133 percent plusmn 28 percent range except avocado and orange (89 and 102 percent respectively) and corn pepper sorghum bean and sugarcane (162 to 186 pershycent)
The chlorophyll of green leaves usually absorbs 70 to 90 percent of the light in the blue (about 450 nm) or red part (about 675 nm) of the spectrum (21) Absorptance is smallest in the wavelength region around )50 nm where the reflection peak is usually less than 20 percent from upper leaf surfaces Avocado and orange leaves with a low reflectance at the 550-nm waveshylength apparently had a much higher concentration of chloroshyphyll than corn pepper sorghum bean and sugarcane leaves
TABLE 4-Reflectance transmittance and absorptance of light at the 1000-nm wamiddotpelength by leaves of 20 crops
Crop I Reflectance Crop 1 Transmittance Crop 1 Absorptance
Percent Percent Percent Lettuce 353 Orange 389 Soybean 18 Onion 385 Bean 420 Bean 18 Pigweed 451 Wheat 446 Peppel 24 Corn 457 Tomato 447 Pigweed 25 Sugarcane 457 Avocado 461 Sorghum 27 Soybean 460 Pepper 465 Peach 28 Cotton 466 Okra 473 Corn 32 Pumpkin 467 Sugarcane 476 Pumpkin 32 Watennelon 468 Watermelon 479 Cantaoup 39 Sunflower 469 Peach 479 Cotton 40 Sorghum 470 Cantaloup 488 Okra 40 CantalolJp 473 Sunflower 491 Sunflower 41 Tomato 483 Cotton 494 Wheat 42 Okra 487 Pumpkin 501 Avocado 42 Peach 493 Sorghum 503 Watermelon 53 Avocado 497 Corn 512 Orange 55 Pepper 510 Soybean 522 Sugarcane 67 Wheat 512 Pigweed 524 Tomato 70 Orange 556 Lettuce 537 Onion 75 Bean 562 Onion 540 Lettuce 110
Mean 1 480 499 40
Standard deviation 1 39 37 17
Crops are arranged in ascending order of their percent reflectance transshymittance and absorptance
1 Lettuce was omitted because leaves were immature
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
26 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
with a high reflectance at the 550-nm wavelength Low pigment content results often in higher reflectance (5 25) J R Thomas Weslaco Tex (unpublished data) has shown that crops vary considerably in chlorophyll content For example sorghum and cantalollp leaves ranged in chlorophyll concentration from 07 to 118 and 64 to 151 mgg of plant tissue respectively Rabideau French and Holt (26) found that light-green leaves of cabbage and lettuce had 8 to 28 percent higher reflectance than the average of six darker green species Thomas also showed a relation between pigment contents of leaves of some crops and their reflectance values
Among transmittances in table 3 orange tomato and avocado (19 to n5 percent) and okra soybean and onion (148 to 188 percent) fell outside of the 98 percent plusmn 42 percent range Tn qeneral the spectral transmittance cwUes for all mature and healthy lea-pes are shnilar to thei1 spectral reflectance curves over the 500- to 2500-mn wavelength interval
The differences among the crop leaves in the visible region are most apparent in the figures on the percent absorptance in table 3 The mean absorptance for the crops is 769 percent plusmn n8 percent All crops fell within the 769 percent plusmn 58 percent range except sugarcane onion bean and pepper with
low absorptances (692 to 706 percent) and peach tomato a vocado and orange with high absorptances (829 to 879 pershycent) The leaves with the high absorptances compared with the leaves with low absorptances have well-differentiated dorsiventral mesophylls with many chloroplasts in their dense palisade parenchyma layers (fig 1) Aboukhaled s made prelimshyinary analyses of the energy balance of single plant leaves from II]OW and high absorptivity categories He concluded that the optical properties of the leaves could be used to partition the total energy absorbed by the leaves into reradiation convection and transpiration
Spectrophotometric measurements at the 1OOO-nm wavelength
The 1000-nm wavelength (table 4) can be used to evaluate the influence of leaf-mesophyll anangement on near-infrared (71)0 to 1350 nm) light reflectance A leaf with a compact mesophyll has lower light reflectance and concomitantly higher transmittance than a leaf with a porous mesophyll (12) In table 4 the mean reflectance of the crop leaves at the 1000-nm wavelength was 480 percent plusmn 39 percent The reflectance of
bull See reference i~hgtd in footnougt 6 p 8
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
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(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
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Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
bull
bullbull
LEAF MESOPHYLLS OF TWENTY CROPS 27
onion (385 percent) and orange and bean (556 and 562 percent respectively) fell outside of the 480 percent plusmn 39 percent lange Only one-half of the tubular onion leaf was used for spectrophotometric measurements Thus discounting onion as an unusual leaf compact pigweed corn and sugarcane leaves (fig 1) had the lowest reflectances (451 to 457 percent) and dorsiventral leaves with very porous mesophylls such as bean orange and pepper had the highest refledances (510 to 562 percent) An exception was the high reflectance of wheat leaves (512 percent) but examination of its photomicrograph in figure 1 indicates that its mesophyll is more porous than those of corn and sugarcane even though they are all members of the family Gra-rnineae (table 1)
The mean transmittance of all crop leaves (table 4) was 479 percent plusmn 37 percent All crops fell vithin this range except orange and bean (389 and 420 percent respectively) and soyshybean pigweed and onion (522 to 540 percent) Omitting onion and lettuce leaves for reasons given previously compact pigweed sorghum and pumpkin leaves had high transmittance and porous dorsiventral leaves had low transmittance The main exceptions were dorsiventral soybean leaves with relatively high transmitshytance (522 percent) and compact wheat leaves with relatively low reflectance (446 percent)
Absorptance values are also given in table 4 the mean of an crop leaves was 40 percent plusmn 17 percent Soybean and bean leaves (18 percent) and sugarcane tomato and onion leaves (67 to 75 percent) fell outside the 40 percent plusmn 17 percent range Soybean and bean leaves with the low absorptance of near-infrared light both have extremely porous mClIophylls (fig 1)
Correlations among spectrophotometric measurements and leafmiddot water content and thickness
Although the literature indicates that thick leaves have higher absorptance than thin leaves (24 26) coefficients for the corshyrelation between absorptance and leaf thickness were low To make a relative comparison among correlation coefficients a level of r = 0775 was chosen as the level of significance because it accounts for 60 percent (r2 x 100) of the variation for the association between two series of variates Yheat was not inshycluded in calculating correlation coefficients because leaf-water and thickness determinations had not been made
Coefficients were calculated using the means of da-ca from 10 leaves of each crop to test the correlation of leaf thickness
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
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1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
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(4) _~_ and RICHARDSON A J
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(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
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(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
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(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
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(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
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(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
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1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
4
28 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
percent water content and grams of water per cubic centimeter of leaf tissue with reflectance at the 550- 800- 1000 1450- 1650- 1950- and 2200-nm wavelengths Negative coefficients that exceeded -0775 were obtained for the correlation between leaf thickness and reflectance at the 1450- 1650- and 2200-nm wavelengths There were no high positive correlation coefficients Correlation coeffi-ients for wavelengths of 800 1000 1450 1650 1950 and 2200 nm were respectively 053 - 042 - 045 - 065 - 053 - 060 and - 052 for the relation between leaf-water content and reflectance 030 - 060 - 065 - 076 - 085 - 046 and - 080 for the relation between leaf thickness and reflectance and 007 -017 -018 -031 -028 -058 and - 031 f02 the relation between grams of water per cubic centimeter of plant tissue and reflectance
The coefficients for correlations of leaf reflectance transmitshytance and absorptance with percent leaf-water content for the 10 leaves of each crop are shown in table 5 Sugarcane corn
TABLE 5-Coefficients f01 c01relation of reflectance (R) lI(tvelenyths 7cith percent leaf-water content of
Correlation coefficients
Crop 1 550 nm 800 nm 1000 nm
R T A R T A R T A
1 Avocado -014 052 -037 -031 030 017 -034 021 034 2 Orange -24 67 -31 -45 62 -29 -49 61 -22 3 Peach -35 58 -15 -55 26 15 -52 20 19 4 Sugarcane 15 46 -41 - 52 54 - 14 - 56 48 00 5 Corn -98 02 29 -39 41 03 -39 38 13 6 Sorghum - 52 - 22 37 - 21 18 04 - 28 06 22 7 Sunflower 32 48 -50 -22 -05 24 -26 -05 26 8 Pumpkin 38 10 -39 -18 -25 31 -20 -25 35 9 Okra -26 40 -17 -24 11 15 -30 01 28
10 Soybean 48 14 - 52 07 - 26 33 14 - 33 39 11 Pigweed 05 72 -67 -17 -03 19 -23 -11 31 12 Cotton 28 -00 -08 53 -06 -52 54 -00 -57 13 Watermelon 44 -06 -15 30 -28 10 33 -30 09 14 Tomato 16 39 -35 -18 27 02 -30 19 19 15 Pepper - 05 - 43 28 44 - 58 04 40 - 58 08 16 Cantaloup -12 59 -45 12 37 -44 -23 20 -04 17 Bean -56 27 06 -67 42 -09 -55 43 -23 18 Onion 24 54 -50 -61 49 47 -62 57 -20 19 Lettuce 54 59 - 29 - 01 - 06 - 24 08 00 - 22
Crops are in ascending order of water content corresponding with figure 3 Wheat is not included
2 Correlation coefficients underscored equal or exceed plusmn 0775
bull
bull
1
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
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1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
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(4) _~_ and RICHARDSON A J
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(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
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(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
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(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
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(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
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(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
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1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
bull ~
bull
bull
JIgt
~
bull
)
LEAF MESOPHYLLS OF TWENTY CROPS 29
pigweed and tomato leaves had negative coefficients that exshyceeded -0775 for the correlation between light reflectance and percent leaf-water content at 1450- 1650- and 2200-nm 550shyand 1450-nm 1450-nm and 1450- and 2200-nm wavelengths middotespectively In general largest coefficients were obtained at the 1450-nm water-absorption band the 1650-nm peak following the 1450-nm water-absorption band and the 2200-nm peak following the 1950-nm water-absorption band Af percent water in the leaves increased reflectance decreased over the 1350- to 2500-nm wavelength interval No coefficients exceeded plusmn 0775 for correlations either of leaf transmittance or absorpt~lce with percent leaf-water content
The coefficients for correlations of light reflectance transmitshytance and absorptance with leaf thickness for the 10 leaves of each crop are given in table 6 Considering the correlations of reflectance and transmittance with leaf thickness soybean was the only crop that had positive coefficients exceeding 0775
tran~mittance (T) and absorptance (A) of light at seven npper leaf surfaces of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm R T A R T A R T A R T A
043 039 -041 052 039 -047 051 043 -047 061 048 -053 -25 48 -38 -29 60 -44 -06 41 -55 -11 59 -54
22 38 -35 04 35 -32 39 42 -43 5 50 -49 -93 -43 75 -91 -01 61 -80 -67 76 -92 -22 58 -78 -34 59 -72 -01 51 -74 -46 59 -75 -21 51 -67 -47 72 -57 -21 55 -59 -58 72 -64 -33 61 -73 -34 57 -59 -21 49 -32 -44 49 -55 -21 38 -25 -59 56 -20 -44 48 -01 -59 57 -15 -48 46 -69 -41 58 -67 -23 51 -56 -51 58 -68 -33 52 -44 -31 35 -20 -32 39 -27 -30 30 -46 -31 35 -80 -50 68 -68 -31 56 -62 -64 71 -70 -36 53
26 01 -11 51 07 -30 -17 05 05 34 11 -21
19 -27 18 39 -25 09 28 -18 10 39 -20 07 -81 -16 50 -72 -01 45 -56 -31 51 -77 -06 39 -18 -70 62 26 -66 44 -18 -70 65 -03 -67 57 -74 -46 64 -59 -36 54 -54 -48 68 -64 -41 54
34 56 -51 41 54 -55 05 49 -37 46 56 -56 -58 -02 22 -65 06 25 -34 -29 34 -59 -00 19
22 13 -15 15 10 -11 40 22 -56 22 13 -12
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
30 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE S-Coefficients for correlation 0 reflectance (R) SUTaces 0 light at seven Wavelengths
Correlation coefficients
Crop I 550 nm 800 nm 1000 nm
T A R T A R T A
1 Soybean 078 -065 -003 085 -089 031 084 -092 052 2 Peach 45 -40 01 54 -29 -12 50 -35 -01 3 Pumpkin 30 -26 -19 -06 -33 29 02 -27 20 4 Pigweed 61 25 -42 64 -35 -17 59 -40 -06 5 Okra 34 03 - 23 46 22 - 67 46 17 - 61 6 Corn -44 -48 58 41 -24 -58 42 -28 -50 7 Pepper 13 -34 13 59 -44 -25 56 -48 -18 8 Cotton -39 -25 37 38 - 22 - 07 34 - 23 - 01 9 Watermelon -23 -68 70 40 - 57 45 34 - 53 43
10 Orange -24 -47 66 12 - 68 63 15 - 69 60 11 Sugarcane -09 -27 24 28 17 -46 23 14 -40 12 Avocado -08 -62 56 56 -56 -26 58 -52 -36 13 Tomato 28 -34 12 54 -44 -37 43 -47 -12 14 Bean 23 -51 27 -35 -61 40 16 -63 72 15 Sorghum -54 -24 39 01 48 -46 00 46 -43 16 Sunflower 23 18 - 22 05 - 04 01 - 02 - 04 06 11 Cantaloup 73 05 -33 25 -04 -14 23 -19 03 18 Lettuce 30 08 -17 -00 11 -07 -29 -11 29 19 Onion -04 -29 20 02 - 27 38 - 07 28 - 28
1 Crops are in ascending order of leaf thickness corresponding with figure 4 Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
at the 550- 800- and 1000-nm wavelengths and a negative coefficient for transmittance exceeding -0775 at the 1000-nm wavelength The reason for this is unknown It seems plausible however that leaf anatomy or cellular configuration is involved figure 1 shows that a mature soybean leaf has a very porous mesophyll with few spongy parenchyma cells compared with the other crop leaves Soybean leaves also had high negative coefficients for reflectance at the 1450~ 1950~ and 2200~nm wavelengths and for transmittance at the 1450- 1650- 1950- and 2200-nm wavelengths Peach pigweed tomato bean and onion crops also had high negative correlabon coefficients for transmittance at two or more of the 1450- 1650- 1950- and 2200-nm wavelengths These wavelengths are within the watershyabsorption spectral range (1350- to 2500-nm wavelength intershyval) and as leaf~water content increased light reflectance and transmittance decreased and absorptance increased High pos~ itive coefficients were obtained for the correlation l)etween leaf
or
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
LEAF MESOPHYLLS OF TWENTY CROPS 31
transmittance (T) and absorptance (A) by uplJer lea 1tpper lea surfaces of 19 crops
COlTelation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-080 -093 092 049 -O~ 089 -078 -093 OJU -078 -094 OM -66 -82 ampl -27 -73 75 -67 -Jili aa -60 -82 82
~ - 04 -10 06 08 -15 08 17 -10 04 02 -17 14 -61 ~ -09 -66 67 -54 -86 M -52 -80 85-~bull -08 -07 08 17 06 -13 -18 -12 16 -05 -05 06 -40 -75 68 -10 -60 58 -41 -76 69 -36 -72 68 -41 -57 61 19 -55 38 -23 -64 62 -25 -59 59 -48 -41 50 -19 -31 37 -71 -48 65 -48 -34 44
~ -33 -52 55 -00 -56 60 -33 -53 57 -42 -58 64 ok -09 -52 63 -01 -65 67 -08 -39 67 -13 -59 66
-54 -26 44 -33 -10 29 -25 -33 33 -46 -19 35gtshy-59 -66 66 -49 -67 69 -41 -69 66 -68 -69 70 -54 -81 82 -23 -69 68 -13 -~ 59 -50 -73 77 -61 -77 77 -71 -73 79 -52 -81 79 -70 -~ 8L -36 -03 22 -26 19 -00 -33 -14 26 -38 02 17 -63 -16 40 -58 -11 40 -02 -23 21 -57 -14 32 -33 -77 68 -47 -65 72 35 -77 31 -46 -76 74
-43 -42 52 -50 -41 52 -41 -40 46 -45 -42 51 ~ -23 -89 ~ -37 -M Jg 05 03 -05 -23 -89 J11
thickness and percent light absorptance for the soybean peach pigweed bean and onion crops at three or more of the 1450- 1650- 1950- and 2200-nm wavelengths
It was thought that the amount of water in the leaf tissue that was placed over the port of the spectrophotometer might have influenced the spectral energy measurements Accordingly grams of water per cubic centimeter of leaf tissue was calculated for each crop leaf used in this study except for wheat Coefficients for the correlations of grams of water per cubic centimeter of leaf tissue with reflectance transmittance and absorptance are given in table 7 There was no correlation between reflectance and grams of water per cubic centimeter of leaf tissue With transmittance coefficients above 0775 occurred only with okra leaves at 1000- 1450- 1650- 1950- and 2200-nm wavelengths The correlation between absorptance and grams of water per cubic centimeter of leaf tissue gave high positive coefficients for okra leaves at 1450 1650 and 2200 nm Variability in grams
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
--
32 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE 7-Coefficients for correlation of reflectance (R) trans at seven Wavelengths with grams of water per
Correlation coefficients
Crop 1 550nm 800 nm 1000 nm
R T A R T A R T A
1 Cotton -033 024 -014 -032 013 J15 -031 010 017 2 Pepper -31 -17 26 -42 12 36 -45 14 34 3 Corn -49 25 -07 -53 57 04 -53 55 10 4 Tomato -08 47 -30 -54 33 47 -42 41 15 bull 5 Cantaloup -63 -02 27 -06 22 -17 -25 24 -07 6 Pumpkin 64 -08 -36 -16 -42 42 -19 -44 49 7 Sorghum -56 -46 54 -03 05 -02 -09 03 06 8 Watermelon 55 -45 14 39 -53 39 41 -56 41 9 Soybean - -37 29 04 -32 56 -50 -25 56 -64
~ ~ ~
10 Bean - - - -23 15 00 -29 26 -14 -15 29 -28~ ~ ~
11 Orange - - - 19 -18 -05 -08 -43 52 -09 -45 55 12 Sugarcane -
~ ~
- - 14 40 -36 -34 44 -21 -38 40 -08 13 Sunflower
~
55 19 -32 12 -27 22 10 -30 26 14 Pigweed 04 -55 48 65 -43 -08 62 - 39 - 08 15 Avocado 11 -16 09 19 -14 -17 18 - 22 - 02-- 16 Okra -29 -40 49 31 -73 34 26 -78 48 17 Peach -49 43 06 -53 67 -31 -52 To -36 18 Lettuce 26 24 -25 -22 -31 39 -49 -50 69 19 Onion -42 19 -06 -22 06 35 -23 14 01
1 Crops are arranged in ascending order of grams of water per cubic centimeter of leaf tissue Wheat is not included
bull Correlation coefficients underscored equal or exceed plusmn 0775
of water per cubic centimeter among okra leaves had an imporshytant influence on their light absorptance and transmittance compared with the variability among leaves of the other crops
Optical and geometrical leaf parameters
The flat-plate model (2) for calculation of effective optical constants of leaves has been applied to leaves of the 20 crops All available values of reflectance and transmittance for the
~
leaves of 20 crops were reduced to average values a b at the 41 wavelengths 050 055 250 fL Optical parameters a b are defined elsewhere (4) Thirteen data points in the vicinity of plant pigment and water-absorption bands were deleted in advance (wavelengths 050 055 060 065 070 140 145 150 190 195 200 245 and 250 fL) from calculations of refractive indices n Such editing is justified because determination of the index of refraction n is weak in the vicinity of absorption bands
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
33 LEAF MESOPHYLLS OF TWENTY CROPS
mittance (T) and absorptance (A) by uppe1leaf sU1faces of light ~
-i C1Lbic centimeter of leaf tissue of 19 crops
Correlation coefficients
1450 nm 1650 nm 1950 nm 2200 nm
R T A R T A R T A R T A
-041 -009 023 -044 -007 026 -014 -007 011 -039 -010 022 11 10 -13 -21 12 02 -08 16 -10 05 12 -12 ~
-53 -02 26 -63 27 21 -50 -17 30 -59 07 23 -12 42 -23 -26 41 -16 -26 33 -07 -15 40 -22
-61 02 24 -39 -00 17 -72 16 36 -46 -02 19 03 -60 46 -04 -53 48 36 -52 37 11 -50 38
-16 -35 34 -17 -19 28 -09 -40 36 -14 -32 35 -05 -64 57 28 -59 50 17 -59 50 10 -60 51 53 56 -56 -01 55 -59 043 57 -54 46 55 -55
35 39 -40 45 38 -43 22 37 -36 47 42 -46 -20 -49 65 -24 -44 60 23 -51 52 -21 -48 58
-69 -31 55 -63 02 040 -62 -48 57 -69 -15 42 -34 -66 62 -22 -61 64 07 -64 54 -33 -64 62
25 -28 11 52 -36 15 16 -11 04 20 -33 22 -22 -21 22 05 - 19 14 -25 -17 20 -06 -15 13 -54 -86 80 -38 -86 83 -28 -81 68 -54 -Jlli ~
13 59 -46 -06 71 -58 44 52 -52 27 68 -61 A
57 -66 78 -70 -70 ampg -45 -22 48 -60 -67 77bull -36 19 -05 -25 17 -03 07 -24 -07 -29 18 -08
bull
Figures 7A through 7T display the 95-percent confidence bands of the dispersion curves Computational and statistical procedures used have appeared elsewhere (13 10) Statistically 95 percent of experimental points fall within the confidence limits The dispersion curves of figures 7 A through 7T assumed to be cubics wavelength A are expressed by the relation
n = s alA (1) where the coefficients aOI aa were determined by regression Table 8 contains the coefficients of equation 1 for all data discussed
The dispersion curves of most of the leaves illustrated in figure 7 are remarkably similar With the exceptions of onion (H) pigweed (L) and lettuce (F) the dispersion curves are characshyterized by similar shapes and relatively close confidence bands For the exceptions mentioned the flat-plate model (2) appears not to apply However the onion pigweed and lettuce leaves
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
34 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
15----------~___ Io_---r---r----
A
A
i z Q lshy 10L--+---L--2~--- 10--_---_--_--L-_ f) 2 ct a u w a u AI o A X
15r------------- 15------r---r--~W o ~
0
J
10 L-_---_-L_-~-10---+---L-~2---- 2
WAVELENGTH (MICRONS)
FIGURE 7-Dispersion curves of light over the 500- to 2500-nm wavelength interval for leaves of 20 crops by index of refraction showing confidence bands A avocado B bean C cantaloup D corn E cotton F lettuce G okra H onion I orange J peach K pepper L pigweed M pumpshykin N sorghum 0 soybean P sugarcane Q sunflower R tomato S watermelon and T wheat
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
35
-4
LEAF MESOPHYLLS OF TWENTY CROPS 15i-------------
1
z e
i= u
A- ct Q I 10UI Q
II I e X UI 0 ~
~
A
~
10
a
IS
Z e j u ct Q 10 UJ- Q
IS~ II e
Igt X UI 0 ~
2 10
2
10 2
WAVELENGTH (MICRONS)
I
2
2 10
2
IO---+-------i2----J
FIGURE 7-Continued WAVELENGTH (MICRONS)
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
36 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
1515
I-M Ishy
z Q
0(0 ltt rr 10 10 ~ u 2 2W rr
15u 0
X w P 0 ~
J1010 2 2
WAVELENGTH (MICRONS)
15 15
oC
bull
z 0 0 ltt a 10 10u 2 2W a 15 15 (0 u 0
X W 0 ~
IO--+------~2--- 10---------~2----
FIGURE 7-Continued WAVELENGTH (MICRONS)
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
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(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
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(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
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(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
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(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
-----------
----------
LEAF MESOPHYLLS OF TWENTY CROPS 37
TABLE 8-Coefficients of dispersion curve n = ~aji for leaves ~
-4 of 20 crops where is expressed in microns
Crop a at a a
Microns Microns Microns Microns Avocado _ Bean - - ---------- shy
Cantaloup --~~-------
~ Corn ------~-~--------
Cotton --- ---------Lettuce _______________
Okra _--------- Onion -- -------- ----Orange ----- --- -shy Peach ----- ------ -shy
A Pepper - ------- ---shy
~ Pigweed -- -------Pumpkin -----_ --Sorghum ----- _---- Soybean - _----------Sugarcane Sunflower --------- --TomatoA -------- ---- shy
Watermelon gt Wheat --------- ---- shy
1398 0063 -0120 0025 1365 059 -067 006 1425 -062 013 -008 1403 017 -065 011 1320 196 -177 030 1792 -878 587 -127 1347 134 -134 022 1481 -217 156 -044 1390 037 -071 010 1347 117 -115 018 1393 005 -031 -003 1721 -628 334 -071 1406 011 -058 007 1408 004 -055 009 1394 003 -033 127 1402 079 -145 032 1355 110 -116 020 1379 062 -078 010 1377 076 -098 016 1487 -185 085 -021
were different from the other crop leaves--only one-half of the tubular onion leaves was used lettuce leaves were immature and veins of pigweed leaves (fig 1) are surrounded by large cubical
parenchymatous cells Table 9 includes the leaf parameters that relate to the amount
of water and air in the leaf As explained previously (1 2 3) the quantity D in the flat-plate model is the equivalent thickness of pure water necessary to produce the light absorption observed in the leaf The quantity N in the model is the number of compact layers into which D must be subdivided in order to achieve the observed partition of energy between reflectance and transmittance The infinite reflectance Roo at 165 p (4) proshyduced by leaves piled sufficiently deep is listed in column 5 of table 9 The quantity Roo can be measured directly the number listed in table 9 however is a calculated value obtained by techniques previously described (4) The entries of table 9 were obtained by adjusting the quantity D over the spectral range 14 to 25 p to achieve the best fit of the leaf absorption k to
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
38 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
the absorption ko for pure water Column 6 of table 9 is the standard error (SE) calculated from the relation
SE = ~[log (kko)]2[n(n-1)]) (2) The summation in equation 2 includes the 23 values at 005-11 intervals over the range 14 to 25 fL This quantity SE can be considered a figure of merit because SE would vanish entirely if the model were exact and the material were water The quantities D and SE in table 9 are positively correlated (1
A
= 0728)
As indicated previously (1 2 3) the quantities DIN and Roo are strongly correlated Figure 8 indicates the relationship The quantity D and the leaf thickness are also correlated with Roo The thinner the leaf the greater will be reflectance produced by a pile of such leaves This fact has important implications in the interpretation of remote-sensing data
TABLE 9-Parameters that specify amount of Water and intercellular air space in leaves of 20 crops
Standard Crop D N DIN Roo 3 error
Microns Number Percent Avocado 190 173 1093 408plusmn07 0022 Bean 219 220 995 469plusmn05 015 Cantaloup 239 156 1528 376plusmn05 016 Corn _ 113 144 1196 418plusmn08 013 Cotton 199 152 1308 397plusmn04 016 Lettuce 524 105 4997 176plusmn15 018 Okra 181 165 1095 426plusmn07 017 Onion 606 113 5336 185plusmn06 094 Orange 209 227 919 447plusmn05 019 Peach 119 165 720 503plusmn05 019 Pepper 189 176 1073 444plusmn06 015 Pigweed 173 143 1211 410plusmn04 017 Pumpkin 152 148 1023 440plusmn05 017 Sorghum 101 151 670 507plusmn07 018 Soybean 111 145 768 508plusmn10 015 Sugarcane 224 155 1441 364plusmn05 022 Sunflower _ 242 154 1571 369plusmn05 017 Tomato 260 170 1527 366plusmn08 019 Watermelon 203 159 1278 399plusmn09 018 Wheat 169 182 924 456plusmn08 017
1 Equivalent thickness in microns of pure water necessary to produce the observed leaf absorption (1)
bull Number of layers into which D must be subdivided to achieve the observed partition of energy between reflectance and transmittance (1)
bull Infinite reflectance at 165 JL wavelength
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
39
1
bull
bull
LEAF MESOPHYLLS OF TWENTY CROPS
60
50
-~ 40
~ IampJ U z 30 ~ U IampJ J lL IampJ 200 IampJ ~ Z iL 10 ~
00 600
ON (JJ)
FIGURE S-Infinite reflectance Roo at 165 p for 20 genera of plant leaves plotted as a function of the characteristic linear dimension DIN
Table 10 is a compilation of the mean absorption spectra in cm-1 units over the range 14 to 25 JL for the leaves of 20 crops These values correlate (r = 0998) with those previously obshytained (3) on other leaves of agricultural interest The published values for pure water are also presented in table 10 for comparshyison
Figures 9 and 10 are comparisons of experimental and comshyputed values of leaf-water thickness obtained by procedures previously discussed (13) The shaded portions on the bar graphs represent plus or minus one standard deviation All data are plotted for the laboratory water determinations that were made on entire leaves Sugarcane corn sorghum and wheat leaves are not included in figures 9 and 10 Their thickness and watershycontent determinations in the laboratory were made on sections of entire leaves With the exc6ption of pumpkin avocado okra tomato cantaloup and lettuce there is no statistically significant difference between water obtained experimentally and water determined theoretically However none of the six exceptions
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
40 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE lO-Mean light absorption spectra of the leaves of 20 crops compared with those of water over the 14- to 25-p wavelength range
Absorption spectra
Wavelength of light Leaf Water
Microns Cm- Cm- 140 143plusmn 10 125 145 246plusmn 20 258 bull 150 165plusmn 15 185 155 99plusmn 3 98 160 68plusmn 3 65 165 56plusmn 3 51 170 58plusmn 4 52 175 72plusmn 4 60 A
180 81plusmn 3 81 A
185 155plusmn 10 98 190 587plusmn 64 810 195 779plusmn187 1060 200 495plusmn 32 680 205 337plusmn 19 430 210 242plusmn 6 260 215 193plusmn 7 190
6 Jl220 176plusmn 160 225 203plusmn 8 180 230 264plusmn 10 220 bull 235 348plusmn 7 310 240 463plusmn 19 430 245 598plusmn 19 600 250 700plusmn 42 830
1 Average from leaves of 20 different crops Each kind of leaf was ~
bullassigned a statistical weight of unity
bull Values for pure water as published by Curcio and Petty (6)
exhibit a highly statistically significant difference (unpaired t 4 (Ii
test) between observed and computed values for leaf water Table 11 includes the absorption spectra over the 05- to 13-fL
range for 11 kinds of plant leaves (first 11 entries) reported in an earlier paper (15) plus the 20 (last 20 entries) crop leaves introduced in the present paper Note that corn appears twice-once in the earlier work and again in the 20 leaves reported in this paper
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
41 LEAF MESOPHYLLS OF TWENTY CROPS
z 0z 0ct 0ILl a zILl I 52 ILl ILl ct 0(I) U IL ct IL U I shy iii 0 )0- ct E ~ a IL 0 I-Cl
ILZ (J)
ILl l ILl gt 00 300 IL a 0 IL ct ua u ~ ~ ACTUAL
250(J) (J) ~ THEORETICALILl Z u 200 I l shy
I- 150 z ILl J ct ~ 100 l 0 ILl
50
0
PLANT GENERA
FIGURE 9-Comparison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviatin
z 0 J IL a ILl l ILl E 0 ~ILl ILl
Cla J 0 0 U ILl Z J I- l I- e[ Z ~ LL ct l- Z
e[ z z E 0iii a ILl e[ I shyl 0 ILl Zz ~ 0 (I) u (J) I shy J 0o
a u
~ ACTUAL~ rn rn ~ THEORETICAL ILl zG 800 J I shy
600
bull 400
PLANT GENERA
FIGURE 10-Compalison of observed and computed values of effective water thickness of leaves The shaded areas represent a variation of one standard deviation
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
- - --
- --
42 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
TABLE ll-Light-absorption spectm of 80 kinds of plant leaves over the 05- to 13-p ~vavelength range
Wavelength in p
09 10 11 12 13Plant leaf 1 05 06 07 08
Cm- Cm- Cm- Cm-Cm-Cm- Cm- Cm- Cm- 06 06 13 17
4 5 5 12 17 Avocado 980 1218 137 07 06
Banana 552 602 97 4 2 2 2 9 16Bean --- 362 462 71 1
2 2 3 3 10 16Begonia 216 193 30
5 4 4 5 11 18Cantaloup 444 543 83
7 6 6 5 12 17Corn 762 817 157 17Corn 702 791 150 5 4 5 5 12 18Cotton 486 580 92 5 5 6 6 12
Crinum -- 295 295 46 3 3 5 4 12 17
Eucalyptus 563 610 97 7 6 6 5 12 16 4 16Ficus 455 481 59 3 3 4 11
Hyacinth - 427 473 77 4 3 4 3 10 16
Lettuce 26 27 10 4 5 6 6 16 23
Ligustrum 449 487 57 3 3 4 4 11 15-18Okra 547 618 112 7 6 6 6 13
- -- -- 17Oleander 547 576 97 8 7 8 7 14 17Onion 134 156 28 2 2 4 4 11
Orange 1036 1213 144 8 8 7 7 14 18
Peach 1121 1371 170 7 7 6 6 12 17
P(p)er 463 535 88 3 3 3 3 10 16
Pigweed 547 783 135 4 4 4 4 11 17
Pumpkin 742 847 134 9 7 7 6 13 18
Rose _ 1081 1288 189 6 5 5 5 10 15 1 3 2 10 15Sedum 104 102 20 1 7 7 6 13 18Sorghum 826 1021 208 9
Soybean 745 914 150 5 4 4 4 11 16
Sugarcane 302 370 84 8 8 9 9 16 21
Sunflower 450 506 86 5 5 5 5 11 17
Tomato 592 820 92 9 8 8 8 14 21
Watermelon 520 620 87 9 8 7 7 14 20
Wheat _ 1057 1083 163 8 7 7 6 13 18
1 Data for the following 11 entries have previously been reported by Gausman and others (15) Banana begonia corn crinum eucalyptus ficus hyacinth ligustrum oleander rose and sedum
~
ltshy
4
A
amp
-4 4
shy
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
LEAF MESOPHYLLS OF TWENTY CROPS 43
Literature Cited (1) ALLEN W A GAUSMAN H W and RICHARDSON A J
1970 MEAN EFFECTIVE OPTICAL CONSTANTS OF COTTON LEAVES Jour Optic Soc Amer 60 542-547
(2) ___ GAUSMAN H W RICHARDSON A J and THOMAS J R
1969 INTERACTION OF ISOTROPIC LIGHT WITH A COMPACT LEAF Jour Optic Soc Amer 59 1376-1379
(8) - __ GAUSMAN H W RICHARDSON A J and WIEGAND C L 1970 MEAN EFFECTIE OPTICAL CONSTANTS OF THIRTEEN KINDS OF PLANT
LEAVES App1 Optic 9 2573-2577
(4) _~_ and RICHARDSON A J
1968 INTERACTION OF LIGHT WITH A PLANT CANOPY Jour Optic Soc Amer 58 1023-1028
(5) CARTER D L and MYERS V r 1963 LIGHT REFLECTANCE AND CHLOROPHYLL AND CAROTENE CONTENTS
OF GRAPEFRllT LEAVES AR AFFECTED BY NASO NACL AND CACL Proc Amer Soc Hort Sci 82 217-221
(6) CURCIO J A and PETTY C C
1951 THE NEAR INFRARED ABSORPTION SPECTRUM OF LIQUID WATER Jour Optic Soc Amer 41 302-304
(7) DUNCAN D B
1955 MVLTIPLE RANGE AND MULTIPLE F TESTS Biometrics 11 1-42 (8) ESAU K 3
1965 PLANT ANATOMY (2d ed) 767 pp Wiley New York NY 1- (9) FAHN A
1967 PLANT ANATOMY 534 pp Pergamon Press New York NY
(10) FREEZE F
1964 LINEAR REGRESSION METHODS FOR FOREST RESEARCH Forest Products Lab Madison Wis p 81
bull ~
(11) FULLER H J and TIPPO O
~ 1949 COLLEGE BOTANY 993 pp Henry Holt and Co Inc New York NY
(12) GAUSMAN H W ALLEN W A and CARDENAS R 1969 REFLECTANCE OF COTTON LEAVES AND THEIR STRUCTURE Remote
Sens Environ 1 19-22
~ (13) --- ALLEN W A CARDENAS R and RICHARDSON A J 1970 RELATION OF LIGHT REFLECTANCE TO HISTOLOGICAL AND PHYSICAL
EVALUATIONS OF COTTON LEAF MATURITY App Optic 9 545shy 552
(14) --- ALLEN W A MYERS V 1 and CARDENAS R 1969 REFLECTANCE AND INTERNAL STRUCTURE OF COTTON LEAVES
Gossypium hirsutum L Agron Jour 61 374-376 po (15) ____ ALLEN W A SCHUPP MARCIA and OTHERS
1971 REFLECTANCE TRANSMITTANCE AND ABSORPTANCE OF LIGHT OF
LEAVES FOR ELEVEN PLANT GENERA WITH DIFFERENT LEAF
MESOPHYLL ARRANGEMENTS Texas A amp M Technical Monograph No7 38 pp
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
44 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
(16) HAYWARD H E 1938 THE STRUCTURE OF ECONOMIC PLANTS 433 pp Macmillan New r
York NY lshy
(17) HEILMAN M D GONZALEZ C L SWANSON W A and RIPPERT W J
1968 ADAPTATION OF A LINEAR TRANSDUCER FOR MEASURING LEAF
THICKNESS Agron Jour 60 578-579
(18) HOWARD J A 1966 SPECTRAL ENERGY RELATIONS OF ISOBILATERAL LEAVES Austral
Jour Biol Sci 19 757-766 4 (19) JENSEN W A
1962 BOTANICAL HISTOCHEMISTRY 408 pp W H Freeman amp Co San
Francisco Calif
(20) JOHNSON R E 1967 COMPARISON OF METHODS FOR ESTIMATING COTTON LEAF AREAS
Agron Jour 59 493-494
(21) KLESHNIN A F and SHULGIN 1 A 1959 THE OPTICAL PROPERTIES OF PLANT LEAVES Dok Akad Nauk
A
SSSR Bot Sci Sec (translation) 125 18-110
(22) LUNDEGARDH H 1966 PLANT PHYSIOLOGY 549 pp American Elsevier Publishing Co
New York NY
(23) METCALFE C R and CHALK L t957 ANATOMY OF THE DICOTYLEDONS 1500 pp Oxford University
A Press London II
(24) Moss R A and LOOMIS W E 1952 ABSORPTION SPECTRA OF LEAVES Plant Physiol 23 370-391 bull
(25) MYERS V 1 USSERY L R and RIPPERT W J 1963 PHOTOGRAMMETRY FOR DETAILED DETECTION OF DRAINAGE AND
SALINITY PROBLEMS Trans ASAE 6 322-334
(26) RABIDEAU G S FRENCH C S and HOLT A S 1946 THE ABSORPTION AND REFLECTION SPECTRA OF LEAVES CHLOROPLAST
SUSPENSIONS AND CHLOROPLAST FRAGMENTS AS MEASURED IN AN
ULBRICHT SPHERE Amer Jour Bot 33 769-777
(27) SANDERS C L and MIDDLETON E E K 1953 THE ABSOLUTE SPECTRAL DIFFtSE REFLECTANCE OF MAGNESltM
OXIDE IN THE NEAR INFRARED Jour Optic Soc Amer 43 58 (28) SHULGIN 1 A KHAZANOV V S and KLESHNIN A F
1960 ON THE REFLECTION OF LIGHT AS RELATED TO LEAF STRlCTURE (Translation) Dok Akad Nauk SSSR 134 471-474
(29) SLICKTER F C WEARDEN S and PAULI A W 1961 LEAF AREA DETERMINATION IN GRAIN SORGHtM Agron Jour
53 187-188
(30) STEEL R G D and TORRIE J H 1960 PRINC1PLES AND PROCEDURES OF STATISTICS 481 pp McGraw-
Hill New York NY
(31) THOMAS J R WlEGAND C L and MYERS V 1 1967 REFLECTANCE OF COTTON LEAVES AND ITS RELATION TO YIELD
AgronbullTour 59 551-554
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
LEAF MESOPHYLLS OF TWENTY CROPS 45
(32) WEBER F P and OLSON C E JR 1967 REMOTE SENSING IMPLICATIONS OF CHANGES IN PHYSIOLOGIC
STRUCTVRE AND FUNCTIONS OF TREE SEEDLINGS UNDER MOISTtRE STRESS Ann Prog Report for Remote Sensing Lab for Natural Resources Program NASA by the Pacific Southwest Forest and Range Expt Sta 61 pp
(33) WIEGAND C L GAUSMAN H W ALLEN W A and LEAMER R V
~
1969 INTERACTION OF ELECTROMAGNETIC TERRAIN FEATURES Proc Earth
ENERGY WITH AGRICtLTURAL Resonrces Program Status
Review Earth Resources Div NASA Manned Spacecraft Center Houston Tex Sept 16-18 1969 Vol II section 22
1-14 (34) WILLSTATTER R and STOLL A
1913 UNTERSUCHtNGEN UBER DIE ASSIMILATION DER KOHLENSAURE
shypp 122-127 Springer Berlin
shy
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
Appendix OJ
res of 10 leaves for each of 20 crops for 41TABLE 12-Average percent light reflectance of upper leaf SU1 ~
wavelengths over the 500- to 2500-nm wavelength interval 0 trJ
lI Reflectance of light at wavelengths of- Z
0800 nm 850 nm 900 nm 950 nm 1000 nm
Crop 500nm 550 nm 600nm 650nm 700 nm 750nm gtt
Pet PetPet Pet Pet Pet PetPet Pet Pet Pet tI c89 68 72 266 479 504 503 501 494 497
Avocado - - -- - 82 t~-~ 558 562 tBean ~ ~ bull ___ _____ bull - - - - 152 185 120 H17 373 557 569 569 565 trJ
Cantaloup ___ _____ 127 100 99 286 461 477 477 475 468 473 ~116 Corn __ __ bull __ - __ 127 162 120 93 248 454 463 464 462 455 457 Z Cotton _________ - 98 118 80 77 286 458 472 472 469 462 466
236 367 346 353 Lettuce ______ ____ bull - -- 276 303 268 337 376 376 375 Olell290 472 490 492 490 484
Okra ~yen~----- - - 108 129 95 92 487 404 396 377 385
Onion ----- 101 116 85 81 250 394 405 c --~ ~
71 289 532 558 559 557 552 556 W89 102 72Orange ~------- ---- 477 495 495 493 490 493
Peach _ _ _ __ - - - - bull - - 96 109 83 86 291 tl 514 507 510 trJ
Pepper ___ ___ - - 128 168 110 93 328 505 516 516 tl
93 90 266 439 457 455 454 448 451 ~Pigweed __ bull - __ 0- 109 124 89 106 291 449 464 463 462 458 467
_ __ __ M _~ ~ ~Pumpkin 102 U8 470
0 j282 458 473 474 473 469Sorghum -- ___ 150 172 133 113
288 456 466 465 463 459 460 gtSoybean _____ - 109 131 87 79 Cl 299 458 469 468 464 456 457 gtJSugarcane _ - - 159 186 134 114
110 84 85 275 454 473 473 471 465 469 0Sunflower 96 c
259 466 484 486 485 478 483 tTomato -- 100 111 86 86 ~ 468 470 470 463 468
Watermelon 119 144 107 99 304 456 c gtJ77 273 502 515 517 514 510 512
~~~-~-Wheat 103 134 96 trJ
~ ) r Y~ bull bullbull
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
rr t ~ ~ P 1 ~ ~l -) J
Reflectance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet 497 493 471 468 471 452 410 263 192 231 566 560 536 535 536 508 449 256 185 246 476 460 470
470 455 464
446 433 442
44S 432 440
445 435 442
419 418 420
367 383 375
206 234 217
148 168 152
191 210 196
t ll gtIJj
363 350 303 296 298 264 214 118 91 104 lil 490 485 466 452 464 445 404 256 181 223 ll
rJl 394 557 494 514
382 554 491 408
333 531 477 485
325 528 477 484
329 530 478 486
290 512 465 464
230 471 430 417
103 312 303 250
68 223 243 176
84 266 288 226
0 CI a c t t rJl
451 462
446 457
428 442
425 440
426 440
406 421
362 374
215 246
156 190
199 236
0 IJj
470 468 455 453 454 443 417 309 247 282 l 462 460 472 486 472 515
458 454 466 480 466 510
445 429 441 454 445 489
445 426 440 452 444 488
444 427 442 454 445 492
431 405 417 427 422 472
401 359 364 373 375 435
277 207 204 205 220 277
218 144 143 144 166 217
261 183 184 189 212 265
~ ll Z l -lt () ~ 0 CI rJl
~ ~
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
~ TABLE 12-Average percent light reflectwnce of upper leaf surfaces of 10 leaves for each of 20 crops for 00
41 wavelengths over the 500- to 2500-nm wavelength interval--Continued gt-J tr1 0
Reflectance of light at wavelengths of- ~ Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nmCrop 0
Pet Pet Pet gtPet PetPet Pet Pet Pet Pet t
Pet Pet olPet Pet PetPet Pet Pet Pet Pet
102 c 231 97 75 t
325 341 332 312 303Avocado 290 80 60 94 ~ Bean ___ 331 384 409 406 375 352 242
gt-J69 86 194 81320 315 289 274Cantaloup 255 299 Z79 72 97326 301 288 231 Corn _ - 271 310 329 76 60 79
323 319 294 279 199 ~- --~~-~~~p-
262 304 Cotton 64 0gt106 62 56168 150 138Lettuce 130 154 168 94 70 94323 308 230288 330 350 345Okra 44 49 c~~~--- ~ 131 94 49172 170 146Onion __ 120 151 rn
398 390 366 354 278 114 86 120 Orange - _ - 333 376
125 105 144 tl364 356 274Peach __ 343 375 389 380 tgt1
66 94322 234 85 d Pepper _ 300 347 369 366 339 l77 58 80291 276 195 Pigweed 261 300 318 313
71 106 0295 216 90346 331 313 zjPumpkin - - 292 326 156282 141 120369 353 342 _ _ bull _ ~ w _ bull~Sorghum 332 361 374 gt102 81 121345 333 255 Cl352 366 363Soybean 319 ~62 82 3M 300 275 259 188 76
Sugarcane 242 280 81 0 266 189 80 65 c305 281
Sunflower 249 293 313 t60 79321 317 289 273 191 73 gt-J
Tomato 256 300 91 c324 299 287 205 80 69
Watermelon 274 312 330 97 90 128 ~ 352 343 273327 364 382 374Wheat
~ ~ lgt ~ J yY
~
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
~ ~ )- c~~~~= J )i
Reflectance of light at waYelengths of-Crop 2050 run 2100 nm 2150 run 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 run 2500 run
Pet Pct Pet Pet Pet Pct Pet Pet Pet Petilvocado __________ ___ 132 157 181 195 174 142 116 95 78 70Bean _ _____________ 141 189 226 240 215 172 128 95 72 59Cantaloup _ _ _ _ __ 111 142 165 175 157 126 99 80 66 60Corn ____ bull _ _ ____ t126 158 183 198 176 144 116 93 75 67 trJ Cotton 108 gt ---- -------- 141 167 168 158 125 98 75 60 I1j53Lettuce bull ____ bull _______ 74 84 92 94 88 77 66 58 52 49Okra __ __ __ bull ___ ____ is128 163 190 202 183 149 118 93 73 trJ65Onion __ _bullbull _ __ rn56 66 76 80 74 63 54 48 46 45 0 Orange __ ____ 158 192 221 236 212 174 141 111
90 78 ~Peach __ __ __ bull _ 183 216 243 257 231 193 160 132 107 95 ~ Pepper _ bull _bull ___ bull _ 132 171 202 215 193 154 117 89 68 57 t
Pigweed --- ----- 110 143 168 178 159 129 99 76 59 51 rn
Pumpkin __ _ bull ________ 0140 172 195 209 182 149 121 96 76 70 I1jSorghum ________ __ 191 221 245 258 237 204 174 147 124 113 ~Soybean ______ _ __ 166 206 235 248 227 191 154 121 95 82 ~
trJSugarcane - _--- - - 105 131 155 164 145 118 95 78 65 60 ZSunflower - _------- 104 132 154 162 144 116 93 76 65 60 ~
Tomato ~~------ --- 107 137 163 173 153 122 95 74 gtlt
60 54Watermelon bullbullbull _ 121 153 177 188 168 135 n108 85 69 62 a
Wheat 166 202 226 244 0 --~----- - --- 217 182 150 122 97 85 rn
Ngtshyco
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
01TABLE 13-Average percent light trpnsmittance of upper leaf surfaces of 10 leaves for each of 20 crops for 0
41 wavelengths over the 500- to 2500-nm wavelength interval ~ tltI
Transmittance of light at wavelengths f- 1I1 a
Z900 nm 950 nm 1000 nm 500nm 550 nIn 600 lim 650 nm 700 nm 750 nm 800 nm 350nm
Crop a-Pet Pet Pet Pet
Pet Pet Pet Pet Pet Pet Pet t Avocado _____ bull ________ 23 41 14 31 249 424 448 454 455 455 461
txI Bean __ bull __________ ____ 36 266 409 420 422 420 415 422 c69 109 55 t488Cantaloup ________ - - - -- 49 87 39 24 275 463 481 486 486 480
~ 507 512Corn bull ______ bull ____ bull _____ 7 226 489 505 509 511 ~37 98 37 493 390 494306 478 491 494 ZCotton 81 131 70 42 -------~-------- 548 526 537495 553 556 555 Lettuce 384 443 395 340--------------- Okra __________________ 41 271 446 464 467 469 467 473
59 148 58 Cgt
Onion _____________ - - - - 117 188 108 66 358 543 557 557 550 529 540 n Orange ________________ 5 5 176 360 382 386 386 384 389
7 19 c Peach _________________ 271 455 473 476 477 476 479 rn35 62 26 28 Pepper ________________ 464 460 465
69 126 64 31 284 448 462 465 tl
Pigweed ______________ bull 37 27 286 492 5Ui 520 520 519 524 tltI54 95 d Pumpkin ________ - - - - - - 56 88 43 56 300 471 489 494 496 495 501 ~
499 503Sorghum _______ - - _ - - - - 50 90 42 21 244 467 491 496 498 0
Soybean _________ bull _____ 54 325 500 514 518 519 518 522 ~100 156 87 Sugarcane __________ bull __ 75 122 69 41 267 450 469 472 473 469 476 shy
cl 63 91 57 51 278 464 484 488 488 484 491
~Sunflower _ _ - - - - - - - -- 15 9 236 419 438 443 444 440 447 aTomato _------------- 26 55
479 c466 471 474 472Watermelon _ _____ bull - -- 52 96 43 20 287 452 t 446 ~ Wheat bull ___ _ __ __ bull --- 19 58 21 7 203 418 434 439 441 439
~
~ gt- ~ lgt ~ ry -- bull
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
~ ~ -~~~ _~middot=77 J)~
Transmittance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 mltl 1400 nm 1450 nm 1500 nm
Avocado _ _ _ __ Bean - shy ~ - - - ~ ~ Cantaloup _ _ ___ Corn - ~ -~~-----~
Cotton - - ~ - -
Lettuce _ _ _ _ _ Okra __ _ ~ _ w _ ~ _
Onion Orange Peach Pepper Pigweed - shy _-Pumpkin Sorghum - ~ - - ~
Soybean _ _ _ Sugarcane _ Sunflower Tomato Watermelon Wheat -
Pet 466 424 495 517 499 549 478 554 395 483 470 529 506 508 526 481 497 453 485 452
Pet 463 419 490 516 496 537 476 541 393 481 467 526 504 507 524 479 492 449 482 451
Pet 450 399 465 497 478 482 460 482 377 471 449 510 middotL91 498 514 460 468 426 463 434
Pet 451 400 466 498 479 474 461 474 376 473 450 512 193 500 516 460 468 426 465 436
Pet 456 402 470 505 483 480 465 481 382 477 454 516 497 504 519 465 473 430 470 442
Pet 440 381 445 490 466 437 450 434 369 467 437 499 482 496 508 449 451 407 450 428
Pet 394 335 392 459 427 359 415 351 337 439 398 458 437 473 480 408 400 359 407 397
Pet 261 173 206 288 267 146 268 125 201 315 239 299 295 351 349 246 222 186 241 243
Pet 205 118 146 205 196 62
193 41
130 262 169 231 238 282 287 173 150 123 183 185
Pet 256 173 197 268 254 111 245 87
172 313 227 291 297 332 343 230 210 179 243 239
f ~ is trJ rIJ 0 d
= ~ rIJ
0 1
gt-I
~ Z gt-I gtlt n ~ 0 d rIJ
en
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
CJ1 TABLE 13-Avemge percent light transmittance of upper leaf surfaces of 10 leaves for each of 20 crops for ~
J1 wavelengths over the 500- to 2500-nrn wavelength interval-Continued ~ tltj
Transmittance of light at wavelengths of-()
x Z1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm 1550 nm 1600 nm 1650 nm 1700 nm Crop ()
Pet Pet Pet Pet Pet gtPet Pet Pet Pet Pet t
88 67 123354 341 251Avocado bullbull 320 358 376 370
54 til 185 37 19 c322 295 279Bean bullbull 249 296 322 t218 42 21 60365 336 320Cantaloup 282 337 366
50 118 ~ 430 431 40G 396 320 65 ~Corn __ - - - - - 351 402 74 45 102381 370 271 ZCotton -
~
332 380 404 403 5 17152 21310 270 244
_ _ bull r -Lettuce 199 266 305 52 107 Jgt359 273 86
Okra _ _bull ~
- - - - ~
- 320 366 392 391 370 0gt 12 5 6 Cll247 220 131243 284 288Onion -~---- - -- 175 62202 53 26296 276 269Orange _ _bull _ - bullbull - - - 235 276 300 c
104 173406 317 126374 4il9 428 423 409 mPeach 63 38 89354 340 250Pepper - 304 353 378 378 tI99 69 135 tltjPigweed _ _
~
__ 371 419 445 444 422 410 303 149 d292 102 83431 411 395 ~Pumpkin _ _ _ 368 412 435
122 199441 366 154462 463 448Sorghum - --~- ~- 399 440 0117 193458 448 355 146 1Soybean __ 413 453 474 475 67 40 93360 348 251Sugarcane _ 307 357 385 384 gt
65 0225 60 23370 366 340 327 ~Sunflower _ 291 344 291 196 37 18 54 ()308 334 333 305Tomato 257 - 61 46 101 c362 353 253Watermelon - 318 365 388 386 t
267 60 52 107 ~ Wheat _ ____ ~
- _ 307 347 368 363 343 337 c j
)0 ~ ~ bull p ~ r r ( bull
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
T~~T r --ltj ~ ~ - ~~ ~ ~ C J j t
Transmittance of light at wavelengths of-
Crop 2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Avocado 173 212 240 252 233 198 162 121 98 69 Bean ~ ~ - - shy 103 153 186 197 184 152 113 78 49 35 Cantaloup Corn Cotton
_ _ _ 115 186 168
169 246 226
205 285 262
218 303 277
201 283 261
164 244 225
121 199 179
81 148 129
50 97 88
34 70 66
t to gtshySJ
Lettuce 45 88 122 135 122 90 56 29 14 8 a Okra 168 222 257 271 257 222 181 136 97 75 tJj
rJJ Onion _ bull _ bull _ _ 25 60 90 102 88 60 31 12 5 5 0
Orange _ Peach ___ ___ Pepper __ bull __ __ Pigweed _ _ _bull _____ Pumpkin __ __ _ _____
103 234 150 207 214
141 281 205 268 268
168 312 242 307 301
181 325 256 322 313
165 306 242 306 294
136 272 208 ~~69
258
107 236 164 222 215
78 191 119 170 167
51 147
81 12l 119
38 122
60 96
102
xl 0lt t t rJJ
0 SJ
Sorghum --- -shy - ---shy 267 319 353 369 354 321 282 236 184 156 gt-3 Soybean bull __ __ bull _ __ Sugarcane bull __
267 151
327 200
363 237
377 250
363 230
330 193
286 151
235 108
185 70
158 49
~ to Z
Sunflower bull bullbull __ 119 171 205 216 197 161 121 82 50 33 ~ Tomato _ _ _ _ ___ 102 152 186 198 182 148 108 72 43 30 Watermelon Wheat
- ~- --shy 161 159
213 204
247 233
261 247
244 228
207 196
166 162
122 123
82 86
63 65
~ 0 11 rJJ
01 CampI
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
- -
TABLE 14-Average percent light absorptance for uppe1 leaf sU1faces of 10 leaves for each of 20 crops for 41 en iPgtshy
Wavelengths over the 500- to 2500-nm wavelength interval ~ txl
Absorptance of light at wavelengths of- 0 t
1000 nm Z 0
Crop 500 nm 550 nm 600 nm 650 nm 700 nm 750 nm 800 nm 850 nm 900 nm 950 nm Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet Pet gt
Avocado __ bull _ ___ 895 870 918 891 485 96 47 42 43 50 42 t
Bean _ _ ____ bull ___ 779 706 824 857 361 34 12 10 115 27 18 bl
8Cantaloup - 835 786 860 877 438 76 42 37 39 52 39 t~ ~
txlCorn ~ -~- -- ~ ~- 836 740 843 900 526 57 32 27 27 39 32 ~ Cotton __ ______ __ 821 751 850 881 408 64 37 34 38 48 40 Z
Lettuce __ _ _ _ _ _ _ 340 254 338 424 168 71 68 70 85 128 110 Okra __ ____ bull ______ t833 722 847 867 438 82 45 41 41 49 40 Onion -~-- ~ -- ~- 782 697 807 853 393 62 38 40 54 94 75 5
0gt -~
Orange _________ ______ 904 879 923 924 535 108 60 56 57 64 55 cPeach 868 829 891 885 438 68 32 29 30 34 28
--~-----~-~- in Pepper --~ 803 706 826 875 388 47 22 19 22 33 24
--~-
Pigweed -- - 837 782 870 883 449 69 27 25 26 34 25 tl txl
Pumpkin _ _ _ ________ il842 795 868 838 409 80 47 43 42 46 32 Sorghum -- _--- - - 801 738 826 866 474 75 36 itO 28 33 27
~
Soybean - - - ~ 791 713 827 866 387 44 20 18 18 23 18 0 gtj
Sugarcane _ _ _ _ ~
___ __ 766 692 797 845 434 92 62 60 63 75 67 gtSunflower _____ __ 841 799 859 864 448 82 43 38 41 51 41 Cl Tomato 874 836 900 9004 506 115 78 71 71 82 70 0 ~
Watermelon 829 759 850 881 409 92 65 59 57 65 53 c t
Wheat 878 807 883 916 525 80 51 44 44 51 42 ~ c ~ txl
~ jI ~ ~ ~ ~ 1 f ~bull
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
~~- - ~ lO 1 A ~
Absorptance of light at wavelengths of-Crop 1050 nm 1100 nm 1150 nm 1200 nm 1250 nm 1300 nm 1350 nm 1400 nm 1450 nm 1500 nm
Pet Pet p(t Pet Pet Pet Pet Pet Pet Pet Avocado 36 44 79 81 73 108 195 476 604 513 Bean 10 21 65 65 62 111 216 572 698 581 Cantaloup Corn Cotton
29 23 32
40 28 41
90 70 79
91 71 80
85 60 75
135 93
114
241 158 199
588 478 516
706 627 u51
613 523 550
t tzj
gt1
Lettuce Okra Onion Orange Peach Pepper Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato
Watermelon Wheat
88 32 52 48 23 16 20 31 22 12 59 32 60 44 33
113 40 77 53 28 25 27 40 25 18 67 43 70 53 38
215 74
184 92 52 65 62 68 47 41
111 91
121 92 77
230 77
200 96 50 66 63 67 48 40
114 92
121 92 76
222 70
190 88 45 60 58 64 42 37
107 86
115 8S 66
300 105 276 119 68
100 95 98 62 61
146 133 166 128 100
427 181 419 192 131 185 180 188 110 119 233 236 269 218 168
736 476 772 486 383 511 486 459 l39 374 547 573 609 540 480
847 626 891 646 495 654 613 572 471 495 682 707 733 651 597
785 532 829 562 399 547 510 468 386 397 588 60S 632 545 496
~ tzj en 0 x gt-ltt t en 0 1
gt-l tzj
Z gt-l gtlt Q ~ 0 en
01 01
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
~TABLE 14-Avenllge percent light absorption for 1ppe1 leaf surface of 10 leaves for each of 20 crops for 41 m Wavelengths over the 500-to 2500-nm Wavelength interval--Continued
t-3
~ Absorptance of light at wavelengths ofshy I Z1550 nm 1600 nm 1650 nm 1700 nm 1750 nm 1800 nm 1850 nm 1900 nm 1950 nm 2000 nm Crop
Pet Pet Pet ~ Pet Pet Pet Pet Pet Pet Pet t Avocado 390 317 283 297 334 356 518 815 857 775
te883 921 852Bean 421 32Q 269 273 330 368 573 c
t854Cantaloup - - - -- -- 463 364 314 350 376 406 588 878 911 ttzjCorn ______ _ _ _ 377 288 241 244 294 316 449 856 878 785 ~820325 351 529 850 895Cotton -_ - - ~- - - 406 317 272 278 Z
742 917 939 919 M bull _ __ ~ ~_Lettuce
~
671 581 527 522 580 618 i- 878 799 Igt-Okra __ _ 392 304 258 265 307 332 497 821
649 775 939 951 945 0gt
Onion - - - 705 606 544 542 607 ~ ~
888 818Orange _ 432 348 302 314 359 177 519 833 c Peach _ _bull 281 216 183 196 226 258 409 749 792 684 ln
895 817Pepper ___ 395 301 253 256 308 338 516 851 t
Pigweed _ 368 281 237 243 288 314 501 824 874 786 tzj Ij
Pumpkin __ 339 261 220 238 276 310 492 808 840 745 t-3 Sorghum _ _ 269 199 164 168 200 216 351 705 759 645
195 159 162 198 218 389 753 802 686 0 jSoybean _ _bull 269
Sugarcane - - 450 360 311 315 365 393 556 857 898 825 gt~
871 912 854 0Sunflower - - - 460 364 317 329 379 407 586 ~
Tomato 487 392 345 351 406 436 613 890 922 867 -Cl
~
a __ bull
859 885 808 cWatermelon ~ ~
408 323 282 291 339 360 542 t--~~~~
306 320 458 842 858 765 t-3Wheat - - - -- ~ - - ~ - 367 290 251 263 ~ tzj
~ bull ) Y fbull
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
T ~ -i -y-~ ~ ~~-- --- ~~ __ ~~~w-__w_ -1 - ~
Absorptance of light at wavelengths of-
Crop
Avocado Bean Cantaloup Corn Cotton Lettuce Okra Onion Orange Peach Pepper _ Pigweed Pumpkin Sorghum Soybean Sugarcane Sunflower Tomato Watermelon Wheat
2050 nm 2100 nm 2150 nm 2200 nm 2250 nm 2300 nm 2350 nm 2400 nm 2450 nm 2500 nm
Pet Pet Pet Pet Pet Pet Pet Pct Pet Pct 694 631 579 554 593 660 722 784 823 861 755 657 588 563 601 676 759 828 890 906 774 689 630 607 642 710 780 839 884 906 t 688 596 532 500 541 612 686 759 828 863 L2J
gtshy724 633 571 633 420 650 723 796 852 881 Xl
881 829 786 771 791 833 878 913 934 943 15 ~ ~ ~ ~- ri _ 7004 615 553 526 560 628 L2J701 772 830 860 (JJ
919 874 833 818 838 877 915 941 949 950 0 ll
739 668 610 583 623 690 752 812 859 884 ~ 583 503 445 419 464 535 604 678 746 783 ~ 718 624 556 529 565 638 718 792 850 882 t
(JJ
683 589 525 501 535 602 679 754 817 853 - 645 560 504 479 524 593 664 736 805 827
0 gtrj
~ ~ ~ ~
542 460 402 374 410 475 544 618 692 0-3732 567 467 402 376 410 479 560 644 720 761 ~ 743 669 608 586 623 689 754 814 865 891 Z 776 697 641 622 659 723 786 836 885 907
j
gtlt791 711 652 630 664 730 797 854 896 916 c718 634 576 551 589 658 726 793 849 875 ~ 675 594 541 509 555 628 688 755 817 850 (1
(JJ
01 -J
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
58 TECHNICAL BULLETIN 1465 US DEPT OF AGRICULTURE
Glossary of terms References by Esau (8) Fahn (9) and Fuller and Tippo (11)
were used for the definitions below
Abaxial
Adaxial
BulJiform cell
Chlorenchyma
Compact leaf
Cuticle
DorsiventraI leaf
Druse
Epidermis
Genus (pI genera)
Directed outwards from the axis (leaf surface faces away from the stem) Directed toward the axis (leaf bull surface faces toward the stem) An enlarged epidermal cell occurshyring in longitl~dinal rows of simishylar cells in the Gr(L1nine(Le It is thought to playa role in the rollshying and unrolling of leaves Chloroplast-containing parenchyshyma tissue Leaf as COlll (Ze(L m(LYs L) with a mesophyll comprised of relativeshyly compact chlorenchyma with few intercellular spaces (nonporshyous mesophyll) A layer of fatty substance cutin on the epiderma1 outer cell walls which is almost impermeable to water A leaf ith palisade parenchyma
~cells on one side of the blade and t
spongy parenchyma cells on the other A globular compound crystal that has many component crystals proshyjecting from its surface The outer cellular layer of a leaf primary in origin if multiseriate (multiple layers of epidermis) only the outer layer differentiates epidermal characteristics A group of closely related species In the binomial system of nomenshy clature the generic name usually refers to some distinctive charshy
~
acter of a plant and the species name is descriptive of a plant
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616
LEAF MESOPHYLLS OF TWENTY CROPS 59
Related species constitute a genus and related genera constitute a family
Intercellular space Space among cells within the leaf Isolateral leaf A leaf that has palisade parenshy
chyma cells on both sides of the blade
Lacuna (pI lacunae) Air space Lysigenous space An intercellular space that origshy
inated by cell-wall dissolutions Mesophyll Parenchyma tissue of a leaf beshy
tween the epidermal layers Multiseriate Consisting of many layers of cells Nectary A multicellular glandular strucshy
ture in leaves that secretes a sugary liquid
Palisade parenchyma layer Parenchyma layer of a leaf mesoshyphyll whose cells have an elonshygated form (palisade cells) pershypendicular to the leaf surface
Paradermal (tangential) Refers to a section made parallel with the surface of a leaf
Parenchyma cell Thin-walled cell found in leaves that is capable of growth and division
Pubescent Covered with hairs Schlerenchyma Thick-walled cells whose principal
function is strengthening plant parts Schlerenchyma cells mayor may not have a protoplast at mashyturity
Spongy parenchyma layer _ _ Parenchyma layer of a leaf mesoshyphyll with conspicuous intercellushylar spaces (porous mesophyll)
Storage cells _ - Large thin-walled cells used for storage of water and mucilages
Succulent leaf ~ Fleshy-type leaves (malacophylshylous) with many cells that store water and mucilages
Transection See transverse Transverse A cross section A section taken
perpendicular to the longitudinal axis of the cell Also called transhysection
-laquo us GOVERNMENT PRINTING OFFICE 1973 0-478-616