J. Agronomy & Crop Science 159, 264—268 (1987)© 1987 Paul Parey Scientific Publishers, Berlin and HamburgISSN 0931-2250

Contribution from Central Institute for Cotton Research,Regional Station, Coimbatore-641003y India

Leaf Growth, Reproduction Growth and Yield in Cotton{Gossypium hirsutum L.)

J. G. BHATT

Author's address: Dr. J. G. BHATT, CICR-Regional Station, Coimbatore-641003, India.

With 3 tables and 2 figures

Received November 17, 1986; accepted February 17, 1987

Abstract

In three genotypes of cotton differing in height, reproductive growth increased with the increase in numberand size of the leaves and was maximum when leaf area was also maximum. After this stage though the leafarea continued to remain high for 3 weeks and then declined, more buds were shed than produced. Withingenotypes the taller type LRA 5166 produced more leaves with greater area than MCU-5 whereas the dwarftype KD (CAKD) had more leaves with lesser area than MCU-5. The maximum leaf area as well as the yield ofseed cotton were one and a half times in LRA 5166 than in MCU~5. Though the maximum leaf area in MCU~5was also one and a half times than in KD (CAKD)., their seed cotton yields were the same. Since even duringthe period of maximum reproductive growth substantially more number of leaves were produced by LRA5166 and KD (CAKD) than MCU-5y maintenance and retention of bolls appeared to depend not only on leafnumber and area but on their photosynthetic efficiency and perhaps nutrient reserves.

Key words: Leaf area, buds and bolls, seed cotton

Introduction

The leaf area in cotton has been reported tocontrol the number of bolls produced andretained, and the leaf area index (LAI) posi-tively correlated with yield (ASHLEY et al.1965). However, in morphologically contrast-ing varieties of cotton no correlation wasfound between LAI and yield as compact vari-eties with low LAI and the spreading varietieswith high LAI gave the same yield of seedcotton even when spacings varied (BHATT 1974,BHATT et al. 1974, and BHATT et al. 1976). Sincereproductive structures have been shown tohmit the growth of leaves (PRIEN et al. 1980),the varietal efficiency for high yield may there-fore depend upon how best the vegetativegrowth can support and help retain more

number of bolls. An attempt has been made toprobe into this aspect of growth of the cottonplant.

Materials and Methods

Three G. hirsutum varieties 1) MCU-5, 2) LRA 5166and 3) KD (CAKD) were field grown under irrigatedconditions. After the emergence of the first twoleaves, six plants of each variety were removed at 5days interval until 125th day after germination whenmost of the early formed bolls opened. The numberof leaves, leaf area and height of the plants wererecorded, and the material was then oven dried forrecording dry weights. The leaf area was measuredwith the Li-Cor Model 3000 Leaf area Meter. Atmaturity the number of sympodial branches, bollsand the yield of seed cotton were recorded on 6plants randomly selected in each variety.

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Leaf Growth, Reproduction Growth and Yield in Cotton {Gossypium hirsutum L.) 265

10 1

o *

LEAF AMCA

. - L R A SUI

. M C U S

— — . K O (CAKO)

i iuas ANO BOLLS

BLRA SI&(

I MCU S

,-130

40 s: 100 110»0 70 80 90

OAYS AFTER GERMINATION

Fig. 1. Leaf area and the number of buds and bolls produced per plant at different stages of growth m threevarieties.

Results and Discussion

The leaf area in Var. LRA increased compara-tively rapidly from the 40th day and rosesteeply after flowering than in MCU-5 and KD(CAKDj (Fig. 1). With an increase in leaf areathe number of buds and bolls also increased inthe 3 varieties and was maximum when leafarea was also nearly maximum. Inspite of

lower leaf area m KD (CARD) than MCU-5the number of bolls in these varieties from 90thto 110th day varied within narrow limits andwas the same on 125th day. The leaf areaduring peak flowering and boiling was fargreater in LRA than MCU-5 and it also pro-duced the maximum number of buds and bolls.With the decline in leaf area after about 105

Table 1. Minimum and maximum area of main stem leaves and sympodial leaves on fruiting branches atmaximum leaf area per plant

Variety

MCU-5LRAKD (CAKD)

MCU-5LRA

KD (CAKD)

Sympodia from below upward1 to 5

Shed91.4— 99.457.5— 63.6

13.8— 85.214.4—109.014.4— 58.2

6 to 10

Main stem leaves99.1—134.0

113.3—160.163.C^ 81.3

Sympodial leaves17.7— 94.117.7—126.111.4— 68.7

11 to 15

62.8—106.1135.1—156.147.4— 89.8

16.3— 81.714.5—128.210.0— 44.1

16 to 20

—

75.4—125.1—

—

18.0— 74.7—

266 BHATT

UO

14

120

100

inUI

5 •»

LRA

. MCU S

• -• KO (CAKO

UImzz

60

40

40 SO 100 12060 70 60 90DAYS AFTER GERMINATION

Fig. 2. Varietal differences in the number of leaves per plant and height at different stages of growth.

days the nunnber of squares per plant began todecrease. On 125th day LRA had more thantwice the number of bolls than in MCU-5 andKD (CAKD).

After 40th day the number of leaves perplant increased and was considerably more inLEA over the other two varieties at all thestages of growth (Fig. 2). After 65 days KD(CAKD) had more leaves than MCU-5 until125th day when there were no differences. Theheight of the plants increased gradually until

about 100th day after germination and the rateof increase was slowed down considerablythereafter.

When leaf area was maximum in the 3 vari-eties, the main stem leaves on the first fivesympodia in MCU-5 were shed (Table 1). ButLRA and KD (CAKD) retained the leaves onthese positions. The leaves were larger in LRAthan in MCU-5 whereas the leaves of KD(CAKD) were smaller than those of MCU-5.Because of its quicker vertical growth LRA

Table 2. Distribution of dry matter in gm per plant at Maximum leaf area

Main stem

19.7Distribution %12.4

20.3Distribution %

8.9S.E. 0.17L.S.D. 0.78 at 5 %

Monopodiaibranches

8.8

5.6

9.1

4.00.090.39

Sympodialbranches

MCU-517.0

10.7

LRA 516625.0

11.01.806.55

Leaves

49.9

31.6

60.0

26.52.398.69

Fruitmgparts

62.3

39.7

112.0

49,611.1240.41

Leaf Growth, Reproduction Growth and Yield in Cotton {Gossypium hirsutum L.) 267

had 5 more sympodia with well expanded mainstem leaves at this stage. The differences in thesize of sympodial leaves followed the sametrend as for main stem leaves. The maximumsizes of sympodial leaves were larger at thepositions 6 to 10 than the first five positions inthe 3 varieties and had increased by 17 cm inLRA compared with 9 and 10 cm in MCU-5and KD (CAKD) respectively. The leaf expan-sion in the sympodial zone 11 to 15 alsoappeared to be quicker in LRA.

In MCU~5 and LRA there were no differ-ences m the dry weights of mam stem andmonopodial branches when their leaf area wasmaximum (Table 2). But the dry weights ofsympodial branches, leaves and fruiting partswere significantly higher in LRA. However, ofthe total dry matter produced, MCU-5 had3 %, 1.6 % and 5 % more dry matter in itsmain stem, monopodial branches and leavesrespectively than LRA which apportioned10 % more dry matter to its fruiting parts.

Both KD (CAKD) and MCU-5 were httleearly as they flowered at one node lower thanLRA (Table 3). The production of fruitingbranches, bolls and seed cotton was signifi-cantly higher m LRA than the other two vari-eties where these characters were more or lesssimilar.

The cotton plant from its original annualhabit to the present day seasonal form hasundergone tremendous changes in its structureand duration. There have been varieties withhighly bushy vegetative growth and those withshort fruiting branches or dwarf but produc-tive stature. In the present study LRA is com-paratively a large plant, KD (CAKD) a dwarfand MCU-5 an intermediate type. Though thenumber of fruiting forms increased with anincrease m leaf area and was maximum whenleaf area was also at its peak, it began to

decrease thereafter even though the leaf areacontinued to be at more or less the same levelfor three weeks (Fig. 1). At these later stagesthe cotton plant is perhaps unable to fully meetwith the nutrient demands of the growing bollsthough the products of photosynthesis maynot be the limiting factor. The decrease innitrogen uptake after peak flowering, dominat-ing influence of growing bolls and cessation ofapical and vegetative growth after this stagehave been reported by EATON and JOHAM(1944), CROWTHER (1934) and WADLEIGH(1944). ASHLEY et al. (1965) also found nocorrelation between number of bolls or yieldwith LAI at latter stages of growth.

The increase in the number of buds and bollsdid not limit the growth and production ofleaves which was much higher in LRA.Though removal of all reproductive growthcaused only msignificant reduction in the areaof individual leaves PRJEN et al. (1980) felt thatit may have pronounced effects on the totalphotosynthetically active leaf area. From flow-ering onwards KD (CAKD) produced moreleaves than MCU-5 though its leaf area waslower (Fig. 2). The production and mainte-nance of fruiting forms thus appeared todepend upon not only the increase in thenumber of leaves and their expansion but bet-ter photosynthetic capacity and retention also.At maximum leaf area both LRA and KD(CAKD) retained their main stem leaves on thefirst five sympodia unlike MCU-5 (Table 1). ItIS interesting to note that fully expanded mainstem leaves as well as sympodial leaves on 6thto 10th sympodium in the 3 varieties and inLRA even on 11th to 16th sympodium hadlarger area than those on the lower sympodia.Thus inspite of accelerated reproductivegrowth more leaves and with larger area wereproduced.

Table 3. Some growth characters and yield of seed cotton per plant at maturity

Variety

MCU-5LRA 5166KD (CAKD)S.E.

L.S.D. at 5 %

Firstfruiting

node

4.35.04.00.180.57

Number ofsympodia

19.026.0

17.01.41

4.62

Numhcr ofbolls

18.3

39.017.53.51

11.47

Yield ofseed cotton

(gm)

76.6118.679.76.79

22.17

268 BHATT, Leaf Growth, Reproduction Growth and Yield in Cotton

Considering the duration of 160 to 165 daysfrom germination to the last picking of seedcotton for MCU-5 and LRA, about 100 daysafter the opening of the first flower is the mostcrucial period within which reproductivegrowth should be balanced with the growth ofleaves. This period is shorter for KD (CAKD)with the duration of 135 days. The genotypicefficiency for boll setting and ultimately thehigher yield has to be maximum within thislimit. Since uptake of nitrogen and minerals incotton is slowed down after peak floweringeven under irrigated conditions, the varietieswith growing leaves which build up nutrientreserves particularly for nitrogen would be in aposition to mature comparatively more bollsset 50 days after the opening of the first fewflowers.

The number of mature bolls retained perplant in relation to the total number of squaresproduced is in agreement with MAUNEY (1979).The maximum leaf area in LRA was one and ahalf times that of MCU-5 and so was the yieldof seed cotton. But though the maximum leafarea of MCU-5 was also one and a half timesthan in KD (CAKD) their yields were the same(Table 3). During the period when reproduc-tive growth was maximum LRA and MCU-5produced 47 and 20 leaves respectively whereasKD (CAKD) produced 39 leaves. Thus in ahigh yielding variety during the active phase ofreproductive growth simultaneous productionand expansion of comparatively more numberof leaves may help retain more number ofmature bolls, and similarly in an early matur-ing type it may help attain the same level ofyield as in a normal variety inspite of lower leaf

area.

Zusammenfassung

Blattwachstum, reproduktives Wachstumund Ertrag von Baumwolle (Gossypium hir-sutum L.)

Bei drei Genotypen von Baumwolle unter-schiedlicher Hohe nahm das reproduktiveWachstum mit der Zunahme der Anzahl undder Groi5e der Blatter zu; maximales Wachs-tum wurde mit dem Maximum der Blattflacheerreicht. In diesem Enrwicklungsstadium ver-blieb die Blattflache gleich hoch fiir etwa dreiWochen und ging dann zuruck; dann wurden

auch mehr Knospen abgeworfen als produ-ziert. lnnerhalb der Genotypen produzierteder grofiere Typ LRA 5166 mehr Blatter miteiner grofieren Flache als MCU-5, wahrendder Zwergtyp KD (CAKD) mehr Blatter auf-wies mit einer kleineren Flache als MCU-5.Die maximale Blattflache und der Ertrag anBaumwoUsamen betrug bei der Sorte LRA5166 eineinhalbmal mehr, als bei MCU-5. Ob-wohl die maximale Blattflache bei MCU-5ebenfalls eineinhalbmal grof^er war als bei KD(CAKD), ergaben sich keine Unterschiede imSamenertrag. Da selbst wahrend der Phase ma-ximalen reproduktiven Wachstums substantiellmehr Blatter produziert wurden von der SorteLRA 5166 und KD (CAKD) als von MCU-5,diirfte die Entwicklung und der Verbleib derKapseln nicht nur von der Anzahl der Blatterund der Blattflache abhangen, sondern auchvon ihrer photosynthetischen Effizienz undden Nahrstoffreserven.

Literature

ASHLEY, D . A., B. D. Doss, and O. L. BENNET,

1965: Relation of cotton leaf area index to plantgrowth and fruiting. Agron. J. 57, 61—64.

BHATT, J. G., 1974; Leaf growth and leaf area indexin morphologically contrasting varieties of cotton.Cott. Gro. Rev. (London) 51, 187—191.

, T. RAMANUJAM, and E. APPUKUTTAN, 1974:

Growth and nutrient uptake in a short-branchstrain of cotton. Cott. Grow. Rev. (London) 51,130—137.

, R. C. SHAH, and A. N. SHARMA, 1976: Net

assimilation rate of cotton in relation to spacing.J. agric. Sci. (Cambridge) 86, 281—285.

CROWTHER, F., 1934: Studies in growth analysis ofthe cotton plant under irrigation in the Sudan.L The effect of different combinations of nitrogenapplication and water supply. Ann. Bot. 48,877—913.

EATON, F . M . , and H. E. JOHAM, 1944: Sugarmovement to the roots, mineral uptake and thegrowth cycle of the cotton plant. Plant Physiol. 19,507-^518.

MAUNEY, J. R., 1979: Production of fruiting points.Proc. Beltwide cotton Res. Conf., pp. 256—259.

PRIEN, S. D . , M . E . T . SCIOLI, J. R. GOODIN, and

J. D. BERLIN, 1980: Reproductive control of leafexpansion in cotton. Proc. Beltwide Cotton Res.Conf., pp. 41—43.

WADLEIGH, C . H . , 1944: Growth status of thecotton plant as influenced by the supply of nitro-gen. Bulletin No. 446. College of Agriculture,University of Arkansas, U.S.A.