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Light effects during pre- and postharvest stages to improve
nutrition of high tunnel vegetables
Kelly Gude, Ph.D. student, Horticulture and Natural Resources
Introduction
• Light intensity and spectral quality impact the accumulation of several phytochemicals (nutritional quality) (Luthria et al., 2006; Oh et al., 2009).
• However, UV-stabilized polyethylene (poly) is common to maintain its condition, which reduces spectral quality by blocking UV-B and reducing light intensity by 15-20% (Rajapakse and Shahak, 2014).
OBJECTIVE: Evaluate the impact of different poly films on spectral quality and a simulated movable tunnel on light intensity regarding photosynthesis, temperature, crop yield, storage life, and nutritional quality of tomato and lettuce.
2017
July - Oct., 2017
May, 2017
Nov., 2017
Oct., 2017
Harvest Fall Lettuce
Transplant Lettuce
May, 2018
Apr., 2018
Harvest Spring Lettuce
Transplant Lettuce
Harvest BHN 589
Plant Tomato BHN 589
July - Oct., 2018
May, 2018
Harvest BHN 589
Plant Tomato BHN 589
May, 2018
Harvest Movable Tunnel Lettuce
Nov., 2018
Oct., 2018
Harvest Fall Lettuce
Transplant Lettuce
May, 2019
Apr., 2019
Harvest Spring Lettuce
Transplant Lettuce
20192018
Materials and Methods
Materials and Methods
3 12’
130’20’5’
14265
4
1
Rep.3
Rep.4
Rep.2
Rep.1
S
W
6 5324
3 65412
5 2361
…………………………………………10’
BU
FFER
…………………… ……………………
BU
FFER
BU
FFER
Rep.1 Rep.3 Rep.4
BU
FFER
BU
FFER
Rep.2
7
1. Standard Poly
2. Std. Poly with removal 2
weeks prior to initial harvest3. Luminance (diffuse) poly4. Clear poly
5. UVA + UVB Blocking
6. 55% shadecloth
7. Open field
Materials and MethodsYield: weekly harvest for tomatoTomato: Total and Marketable (lbs/plant), Total and Marketable (lbs/sample), Marketability
(Weight %), Biomass samples (g) (9/14)Leaf Lettuce: Total and Marketable Head Weight (g/head)Movable Tunnel Leaf Lettuce: Total and Marketable Head Weight (g/head)
Treatment Effect: measured thrice one week prior to harvest1. Chlorophyll content (SPAD, light transmittance/absorbance), UV-A, UV-B (8/8)2. Canopy and Soil temperature (temperature °F taken in 30 minute increments with
temperature probes)3. Photosynthesis (CI-340) PAR, leaf temp., internal CO2, net photosynthesis rate, transpiration
rate, leaf stomatal conductance rate
Materials and Methods
Storage Quality and Nutritional Quality:1. Water loss throughout storage (%), texture (N and sample wt.), dry matter content (%)2. Phenolic Acid/ Flavonoid (coumarin, chicoric acid, chlorogenic acid, caffeic acid, ferulic acid,
rutin, kaempferol, naringenin, quercetin), 1. Vitamin C (µg AA/100g) in tomato2. Anthocyanin in Lettuce
Materials and Methods
Breaker
Light Red Maturity, measured:(1) on the day of harvest and (2) ‘mature red’ maturity
Breaker Maturity, measured:(1) on the day of harvest, (2) ‘light red’ maturity, and (3) ‘mature red’ maturity
Determined by a* value ((-)greenness to (+)redness)
Light Red
Breaker Mature Red
-4.91 22.90 27.28
Results – Tomato
b
a
b b b
c
0
200
400
600
800
1000
1200
1400
1600
1800µ
mo
l/m
2 /s
PAR (P < 0.0001)
Photosynthetic analysis of BHN-589 in 2018. Photosynthetic Active Radiation (PAR) (µmol/m2/s) measured 8/1, 8/3, 8/5.
*Representative of open field
Results – Tomato Tomato 2017
TRTsTotal Marketable Total Marketable Marketabilitylbs/plant lbs/plant lbs/sample lbs/sample Weight (%) Number (%)
Standard 16.51 a 12.97 0.41 0.40 78.94 80.43
Removal 16.02 a 11.66 0.44 0.44 72.80 72.67Diffuse 17.03 a 13.26 0.42 0.42 77.79 78.00Clear 17.29 a 12.93 0.45 0.46 73.91 73.00
UVA/B Block 15.25 ab 11.83 0.41 0.42 77.69 76.43
Shade 10.13 b 8.71 0.36 0.36 85.55 84.72
P < 0.01
Tomato 2018
TRTsTotal Marketable Total Marketable Marketabilitylbs/plant lbs/plant lbs/sample lbs/sample Weight (%) Number (%)
Standard 12.89 ab 10.54 ab 0.33 ab 0.34 81.84 79.35 ab
Removal 11.72 ab 8.79 ab 0.30 b 0.31 75.89 73.13 b
Diffuse 15.04 a 12.14 a 0.35 ab 0.35 80.81 80.81 abClear 15.62 a 12.15 a 0.36 a 0.36 77.45 76.73 ab
UVA/B Block 14.24 a 11.06 ab 0.37 a 0.36 77.65 78.66 ab
Shade 9.48 b 7.94 b 0.33 ab 0.33 83.96 85.52 a
P < 0.01 < 0.01 0.01
Table 1. Yield analysis of all fruit from weekly harvests in 2017 (7/10-10/3). Treatments marked with different letters are significantly different (α < 0.05). Tukey’s HSD.
Results – Tomato
Vitamin C, measurement of ascorbic acid content of ‘Light Red’ and ‘Breakers’ mature groups.
0
5
10
15
20
25
1 2 3 4 5 6
Asc
orb
ic A
cid
(µ
gAA
/10
0g)
Light Red Maturity
Light Red Mature Red
0
5
10
15
20
25
1 2 3 4 5 6
Breaker Maturity
Breaker Light Red Mature RedStandard | Removal | Diffuse | Clear | | Shade SP SP2W DP CP UVAUVB SCSP
UVA/B Block
Standard | Removal | Diffuse | Clear | | ShadeUVA/B Block
Summary – Tomato Yield• 2017, statistically similar total yield (lbs/plant) for all treatments except
the shade treatment produced less total yield.• 2018, statistically similar total yield (lbs/plant) for treatments diffuse,
clear, and UVA/B block with shade producing less total yield.• Although total yield was higher in 2017, marketable yield was
similar between both years, while marketability (weight and number %) was greater in 2018.
Photosynthesis and Nutritional Analysis• Removal treatments with highest PAR, other treatments are significantly
similar except for shade• Chlorophyll and ascorbic acid content was statistically similar across
treatments.
Results – Lettuce
49
51
53
55
57
59
61
12:00 AM 2:00 AM 4:00 AM 6:00 AM 8:00 AM 10:00 AM 12:00 PM 2:00 PM 4:00 PM 6:00 PM 8:00 PM 10:00 PM 12:00 AM
1 2 3 4 5 6 7
Soil temperature of lettuce in 2017 (10/7-11/17).
Fall, 2017
Trt Soil Temp. (°F) Canopy Temp. (°F)
1. Standard 56.39 BC 50.93 A
2. Removal 54.57 D 50.60 AB
3. Diffuse 57.26A 50.66AB
4. Clear 57.19 A 48.79 C
5. UVA/B Block 56.87 AB 49.42 BC
6. Shade 56.08 C 48.80 C
*Open Field 52.81 E 50.80 A
P <.0001 <.0001
Diffuse and Clear Poly. with higher soil temperatures than other treatments (Std., Removal, Shade, Open). Tukey’s HSD.
Results – Lettuce (Fall, 2017)
Yield analysis from fall harvests in 2017 (11/3-11/17) *Open field not statistically analyzed
Red Leaf
Trt Fresh Wt.(g/plant)
Core length(cm)
Leaf Area(cm2)
Moisture Loss D5 (%)
Dry Matter (%)
Standard 51.93 A 17.26 A 141.5 A 11.48 7.71
Removal 51 A 16.06 ABC 120.28 AB 11.53 7.56
Diffuse 52.13 A 16.71 ABC 120.59 AB 11.17 7.27
Clear 45.57 AB 15.58 BC 105.32 AB 11.21 7.22
UVA/B Block 39.58 AB 15.16 C 96.04 B 15.04 7.77
Shade 29.61 B 16.18 ABC 99.1 B 16.56 7.91
*Open Field 14.1
P < .01 < .05 ns ns
Green Leaf
Trt Fresh Wt.(g/plant)
Core length(cm)
Leaf Area(cm2)
Moisture Loss D5 (%)
Dry Matter (%)
Standard 68.67 A 18.43 127.22 18.23 AB 8.92
Removal 79.67 A 18.13 139.27 15.97 B 8.82
Diffuse 68.69 A 18.31 142.4 19.39 AB 8.60
Clear 62.44 AB 17.48 136.07 18.78 AB 8.64
UVA/B Block 56.65 AB 16.67 124.92 19.49 AB 8.68
Shade 40.68 B 17.52 120.06 25.5 A 8.14
*Open Field 17.51
P < .01 ns ns < .1 ns
Results – Lettuce (Spring, 2018)Spring, 2018
Trt Red Leaf Fresh Wt. (g/head)
Green LeafFresh Wt. (g/head)
Standard 156.54 137.88
Removal 153.67 158.83
Diffuse 158.86 145.54
Clear 149.06 136.97
UVA/B Block 138.63 131.37
Shade 114.63 115.37
*Open Field 10.74 35.87
P ns ns
Yield analysis from spring harvests in 2018 (5/3-5/10).*OF not statistically analyzed **NS between treatments for quality parameters
Results
40
42
44
46
48
50
52
1 2 3 4 5 6L* (
ligh
tnes
s(+)
> d
arkn
ess(
-))
D0 D5
Color measurements from Red Leaf spring, 2018 (5/3-5/10). Analysis days analyzed separately, L*D0 NS, L*D5 P < 0.05
1 2 3 4 5 6 7Standard Open FieldDiffuse Clear UVA/B Block ShadeRemoval
Standard | Removal | Diffuse | Clear | | ShadeUVA/B Block
Results
-14
-12
-10
-8
-6
-4
-2
0
1 2 3 4 5 6
a* (
gree
nn
ess
(-)
< re
dn
ess
(+))
D0 D5
Color measurements from Red Leaf spring, 2018 (5/3-5/10). Analysis days analyzed separately, a*D0 P < 0.01, a*D5 P < 0.01
1 2 3 4 5 6 7Standard Open FieldDiffuse Clear UVA/B Block ShadeRemoval
Standard | Removal | Diffuse | Clear | | ShadeUVA/B Block
Summary – Lettuce Leaf Lettuce • Yield: standard, removal, and diffuse with the greatest lettuce yield
(g/plant) for both Red and Green leaf in fall, 2017.• Nutritional Analysis: Treatments removal and clear with darker,
redder color valuesTBD on correlation to nutrient accumulation
• Temperature: diffuse and clear poly had statistically higher soil temperatures in comparison to the rest (P < .0001)
12’
2’
North
66’
Standard48 h Removal1 wk Removal2 wk Removal
4’
Movable Tunnel
Results – Movable Tunnel
Green Leaf
TRTs Fresh Wt. (g/head)
Core Length (cm)
Leaf Area(cm2)
Moisture Loss D5 (%)
Dry Matter (%)
Standard 105.97A 17.31 A 120.30 18.23 7.60 AB
48 h removal 122.96A 17.98 A 114.88 19.52 6.26 B
1 wk removal 103.05AB 16.83 A 103.55 19.31 7.31 AB
2 wk removal 69.60B 13.96 B 82.87 17.16 8.47 A
P < .05 < .05
Red Leaf
TRTs Fresh Wt. (g/head)
Core length(cm)
Leaf Area(cm2)
Moisture Loss D5 (%)
Dry Matter (%)
Standard 76.69 15.90 a 140.20 A 14.65 7.34 A
48 h removal 88.11 14.98 ab 107.14 C 25.90 5.82 B
1 wk removal 97.36 15.19 ab 127.63 AB 29.56 5.72 B
2 wk removal 67.71 14.41 b 111.75 BC 29.39 6.27 AB
P < .1 < .01 < .01
Yield: 2 week removal (plants exposed to full sun 14 days prior to harvest) resulted in less yield (g/plant) for Red and Green leaf
AcknowledgementsMANY thanks to Olathe Horticulture Recreation and Extension Center (OHREC) team for harvest and management support (Paul Anderson, Cassidy Fleck, Ashlee Skinner, Carley Estes, Kim Oxley, Brian Boutte, Vicente Mascote, Tracy Oelschlaeger, Claire Barnhart)
MANY thanks to KSU-Olathe Postharvest Team for analysis day all-hands-on-deck support (Joe Rundquist, Tricia Jenkins, Kostas Batziakas, Helena Chiebao)