A STUOY DF PEARL MILLET/GROUNDNUT INTERCROPPING WITH PARTICULAREMPliAS I S ON THE tFF I C I ENC I ES or Lt:AF CANOPY AND ROOT I tlG PA TTERr~

AgronomistsICRI5AT

Prepared for the I nterna t iona I I n tcrcíopP in~ Workshep,10-13 January 1979, ICRISAT, Hyderabad, Judia

A study af pear11979 FL - 00448

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ItRY,tOfi. ..P'I,AR\.. ,MILU:T/GROUNDNUT INlERCROPPING WITH PARTICULAR:M,ne;" ON TH~ EFF I C I ENCI ES OF LEAF CANOPY AND ROOTI NG PATTERN,;1, ., ', .•

;J! Fif. "'''','i: "A d~t.l1ed study was carried out on pearl mi Ilet/groundnut

'~rôP~ln~ .~ ICRISAT Center during the ralny seasoll of 197d. Solere groWn on )0 em rows and a slngle Intercropping treatment

';~~

. jnod In a 1 mlllet : 3 groundnut row arrangernent wi th the same~~r9wIpaclngs ~s the sole erops.t~,!~<\;'

The·lntercrop produced a yleld advantage of 2~~ for total dry~~;r(LER • 1.28) and of 26% for seed and pod ylelds (LER Q 1.26).

i:v'lues were a150 computed for leaf area Index and rootlng density,~'

;'these'gavé 'advantages' up' to 30% and 18%, respectlvely. There

,.:"no real evJdence that the Intercrop root sY5tem was any more effi-!!,.,;"i:i~,il{".,:-,, .ti~t"an'the·'root systems of the sole crops. Consldering the leaf...~~(" ' ,

y,:howéver, It was concluded that the dry matter yield advantage'he Intercrop was produced by improved efflcleney of conversion of(;,.,~:. '

f·::.nd not by the Interceptlon of more I ight.

A STUDY Of PEARL MILLET/GROUNDNUT INTERCROPPING WITH PARTICULAR EMPHASIS,ON THE EFFICIENCIES OF LEAF CANOPY ANO ROOTING PATTERN

Research durlng recent years has provlded sufflcient evidence ~p....;,suggest that substantlal yleld advantages can be achievcd fron intercropplng

v~L·ú,compared to sole cropping. But consldering the Incrcaslng emphasls oni'

'~fntercropplng research during the last few ycars. there have ~til 1 becn fewi ":detafled growth studies (Kassam and Stockinger 1~73. Lakhani 1976, Willey

.• rid Natarajan 1978). And yet there is an obvious ~eed for a beLter under-"'stàndfng of the competitlve effects betvleen component crops and their

response to environmental factors such as 1ight. soi 1 moistlJre ando nutrients.

A number of research workers have found that crop cümbinations havingshade tolerant legumes with non-climbing habit such as groundnut. cowpeas,loyabean or phaseolus beans. with maize. sorghum. millet. cotton or castor

!~beans have given greater overall yield trom intercropping compared to solecroppfng (Bodade,1964; Enyi,1913; Evans,1960; Evans and Sreedharan, 1962;

'Oslru,1974; SchI1l1ng,1965; Willey and Oslru,1972). Tht::seyield advantageshave been attrlbuted to the fact that differences between the crops. e.g.

, Jn helght, rootlng pattern or maturity period, can enable better spatialand/or temporal uttllzation of light, 50il moisture and nutrients.

In the ICRISAT Intercropplng programme. pearl millet/groundnutcombfnatlon has been chosen as a typical representative of this non-Iegume/low growlng legume sltuation because of its importance in many areas of theAfrlcan seml-arld troplcs and because it eomprises two ICRI5AT crops. Inltialagronomlc studles at ICRISAT have shown that thls mixture is capable ofproduclng yteld advantages up to 25-30%. Thls paper briefly reports someof the findings trem a pearl mfllet/groundnut intercropping experiment earriedout to obtain some bastc information on growth and resource use.

lhe experirnent was conducted during the monsoon season of 1978 on amediurn deep Alfisol with an avatlable water holding capacity of approximately

~ 100 mm In the top 90 em of the profile. Rainfall durlng the growing perlodwas 968 mn, whlch was above normal and also well distributed during the seasoq~

i

three;treatments in four randomlsed bloeks.;' ~

501. pearl mll1et,

Sole groundnut"ntercrop of .1 row pearl mi Ilet : 3 rows groundnut.

j~' 10 t~ls expertment a replaeement series teehnique was employed wherein

;';tJ'~~r;th"m;lllet/three-fourths groundnut proportion \~as achieved by rcplacing

Y$:/~~r,th ~O't:" of sole groundnut by a row of mi Ilet. This kept a standard~~h.J,,~r,ow splcing for each crop, whether in sole cropping or intereropping,

:kl;}~(attemp~ed to malntain a constant total populatlon pressure for both,',~\r:~~r.~~s an4 the Intercrop. This was done to faei I i tate comparisons bctwecn~~Li,9Ie' crop$ and the intererop, although It was appreeiated that in practice

... "tntercrop mtght have a somewhat higher optimum population requi rernent:.h···"'~han the sole crops. AlI treatments were on 30 em rm'ls and within-rO'tl spacing

,1;,10 em and l5 em for mlllet and groundnut respectively. A fertilizer

. ppltcation of 50 kg/ha of P205 was applled to aIl treatments, and both$oleand tntercrop mfllet were top dressed with nitrogen at a rate of 80 kg/h~.~oth crops were·sown on 25th June; millet was harvested on 16th September

fAd groundnut on 8th October. Cultivars were BK560 Millet and Robut 33-1

roundnut.

Dry ~tt~r and leaf area sampling was carried out at weekly intervals

tarttng from~O days after sowlng. Sampling areas were 1.8 m2 for sole crops'. 2

nd a total of 2.4 m (2 rows of millet + 6 rows of groundnut) for the inter-

rop~ Llght lnterceptlon was measured uslng tube solarimeters (Szeiez,

ontelth and Dos Santos, 1964). One solarlmeter per plot In sole crop treat-

nts'and tlo«) solarlmeters per plot In the intercrop were placed at ground

1.v~1 and the dtfference between the5e and a 'contrai' solarimeter recordingfui' Inçfdent Ifght was measured ?s integrated dai Iy totais.

Rootlng patterns were examined by coring on seven oceasions, at vleekly

lntervals lnltlal1y and at 10 day intervals later. Core samples of 6.8 emLameter were taken on the crop rows and also mld-way between the rOW5. This

ave two corlng posttlons in the sole crops but flve dlfferent posltions to

over the ful1 Intercrop pattern (see Figure t); these five positlons \'Ieít~

ece5~ary because of the likelthood of growth being different in the miJdlc

roundnut row compared wlth those next to the mlllet.' ....• ,~,

These cores were dlvided Into sections representing depths of0,,10, 10-20, 20-30, 30-"40, 40-50, 50-70, 70-90 em. The sectlons weresoaked In water overnlght and then the roots were washed out using 0.5 mm$Ieve. Roct length was estlmated In each seetion by the 'Iine intersect'me~hod (Newman 1966) by spreading the roots out randomly on a piece ofgraph paper wlth 1 em squares.

c;

Mean root density (em root/em3 soi I) across alI sampling positionswas then ealculated at eaeh profile depth for each sole crop and the inter-crop. For the sole crops, the two sampling positions were ~veraged, forthe Intercrop the different sampling positions had to be given differentwelghtings so.the Intercrop pattern was correctly represented (see Figure 1).

Soil molsture, nutrient uptake, nitrogen fixation and crop conductancestudles were also condueted in this experimcnt but only the data on drymatter accumulation, leaf area index, rooting patterns and Jight utilizationare reported here.

lhe patterns of dry matter aecumulation in the sole crop5 and theIntercrop of mlllet and groundnut throughout the growing season áre shm'inin Figure 2. One striking feature to be ~een In the curves is the timedifference In the erop growth between the two sole erops although they were$own at the same time. It is evident that millet ,establlshes early andInltlally has a faster growth rate than the slower establhhing groundnut.Sole millet had a consistently higher rate of dry matter accumulation thansole groundnut. At final harvest, the dry matter aecumulated by solemlllet was 8134 kg/ha eompared to 4938 kg/ha produced by sole groundnut.tn the intererop, It can be seen that the growth of groundnut was onlysllghtly less than the 'expeeted' leveI (I.e. the levei that would havebeen achieved if the mi 11et row had produced exactly lhe samc d.:gree ofcompetition as a groundnut row). On average, the groundnut IJroduced a drymatter LER of between 0.7-0.8 compared to the 'expected' LER of 0.75.Hlllet on the other hand suffered less cOlllpetltiollill intcrcropping andproduced dry matter lERs of between 0.5-0.6 compared with an 'expected'LER of 0.25. lhe partltionlng of dry matter clearly indicated that theaddltlonal dry matter of millet in intercrop was due to an increased

- number of tlllers per planto

Gralo or pod ylelds, total dry matter at final harvest, and harvestIndex .re shown 10 lable 1. Sole mi llet produced 2226 kg/ha grain yield andIntererop mlJlet 1227 kg/ha, glving an LER for millet grain yield of 0.55.Sole groundnutpod yleld was 1185 kg/ha compared to 840 kg/ha for the inter-crop glvlng an LER for groundnut pod yield of 0.71. lhis gave an overalllotercropplng advantage for graln or pod yleld of 26% (i.e. a total LER uf1.26)compared to 28% Intercropping advantage obtained for total dry mattcrat final harvest. Harvest Index of the Intercrop of both specles was olllyone percent hlgher than the sole crops.

Leaf area Index (lA!), of sole and intercrops is shown in Figure 3.Haxlmum LAl ln mlllet was reached at about 45 days afte( 50wing and was2.62 and 1.49 for sole and intercrop respectively. Maxirnum LAI in grouncJl)IItwasachleved at about 60 days after sowing and was 3.09 and 2.32 for sol~and Intercrop respectlvely. LAI values showed palterns 11\ agreernent with thv',eof the other growth factors. LER values based on l.AI5 were calculated il'lJshowed that the LER for mil1et LAI was between 0.5 - 0.6 throughout the a<:tivc.~gr~wlng period. lhe LER for groundnut LAI was about the expected value of0;75 untll mi Ilet was harvested. but after the mi 11et harvest i t even reachcJ.0.89. lhe total tntercropping advantage In ter.llSof il1creased lAI durin~J rlle·,1.of the growtng period averaged about 30%, bút arollnJ 70 days when the mi 11elwas senesctng, it even reached 39%. This sugges~s a beneficial interactionbe't~e~n the canoples, slnce the Intercrop was able to support much more leaf." '. ;,,,,~,,",,,,,,,,,,.;.; .••.• ~,.;, •••• ,>

.th~".'.expec ted.

llght interception patterns are presented in Figure 4. As expccted, solemillet established ground cover most rapidly and reached approximately eo~ lightlnterception at about 40-45 days after sowing. Sllbsequentlya peak intercqlionof 86% was achleved at about 50 days but 'this dropped back to 60% near finalharvest. The much slower development of the groundnul c.:..rl()~Ywas partic1,IL.J(lyappare.nt, as at 40 days after sowlng this crop had intercepted only 4:J~ 01

Incident llght. At about 65 days it had reached a near lnaximum value of abau!85% and thls was more or less malntained until the final harvest. A siniÍl3r

time dlfference between the two specles was observed for achieving maXil.,Ui:1;(;ufarea development, and In fact the peaks af llght interception and leaf ~re0development colnclded.

.• ,0#

In the lntercrop, attempts werl: :ni~'L: to rnC:<:Jsure lhe ",iliount '.If Jight

Intercepted by each individual crop, but thi:, ,1':'5 pos~iblc on1y during lhe, • "o,

mlddle of the season and by that time I~c'~,k ill:,(~rccptjon value. I'I<':i'(: already

'achieved. Thus lhe curves in Figure 4~ho\'J th~ total inteI'C\~pliGi1 uy both

crops. The levei of interception by tiw j'll' rcl'op V'Jas inter'i,cu:<::tc betw'~ên

the two sole crops, as expected, unti I mi llcL Ivil:.) harvested; i t lias then

reasonabJy constant until the groundnut -,pn-::s';;cd. The Iflélximun, ínt.:.'rceptiun

of 82% by the Intcrcrop was achieved 60 da)'s at'ter' s<Ming.

The efficiency wilh which lhe int·:rc.l~plt~d ligtlt ene.-S1Y wa:i.o;wertcd

lnto dry matter during the growing periorl ís Illustrated in Figure 5. Althaugh

groundnut has a 20 day longer maturity diffcl'cl1c:e over llIillet, al final htlr'lest

It had lntercepted 19.25 Kcal/cm2 comparcd tu 14.26 Kcal/cm2 by th? 1lillet.

At millet harvest. the total energy intercêpted by the intercrr;p ",éb 12.5 Kcal/cmZ

compared wlth 12.64 Kcal/cnrZ interceplec1 by the sole groundnul. Al final harvest

of groundnut lhe total amount of light energy intercepted by the !ntercrop was

17.3 KcaJ/cm2 which was only slightly less than 19.25 Kcal/cmL intercepted by

the sole groundnut. Considering the cfficiu1cy ~vith vlhich ttl;~ irlLcrcepLed

lIght energy was converted into dry matLer, I;,illet \<Jas mL!ch n,ol'(' ·.;tficient

than groundnut. t1i1let produced 5.7019 ()f dry íll<.ltter per kilocalorie inter-

cepted. whilst groundnut produced only 2.~)7 IlIq. Tt1Cse diffel"cnt ~:fficÍC:ncie5

of light energy conversion were presumably du<,~ to difrerenct~-':; in p!lo~osynth(;;tic

rates of the two species i.e. C4 as cOIf,par'~_~ to C3• The efficicncy of the

lntercrop to convert intercepted light ener~y irlto dry malter was 51 ightly

but consistentJy higher théln sole mi IleL up to 6) JdY:;, but ()n~,- I::i llet started

senesclng the effic.lency fell and follc,·,ed the pattern úf Qrocu:Jnut. l\t. final

harvest, the Intercrop had proJuced 4.6 :ng vf dr,/ fIl;)ltcr p.::r ki i(;(aíoric i'lt,,;r-

This efficiency of light energy cCollv..;rsío/l by t.he intercro::; is of

particular interest because this must indic.Hl~ to what extr~nt tl1,-, (:;r',-,uter dry

matter yield of the intercrop was due to the Intercep~ion of '[(,1'(; 1ight or more

efficient use of light. In facto If th(~ drr rr:()tter yielJ of e,:d. u;n.ponent in

theintercrop had been produced at the same efficienc.y as the é.(JqJ]rable sole

crop, the total 'expected' interceptlon would have been 22.111 r.c\..:!~ cO:1Dared to

the actual Interception af 17.25 Kcals; also lhe 'expected' raLe :.Ji ::fficlency

. ~ould have becn 3.59 rng/Kcals comparcd \'.ilt. tr;c actu·::d of 4.t j/;,.c.al. So

;~,.{"

cleàrly the intercrop was converting Jight more efficiently, and calculatiL;1l

show,that It W8S actually 28% more efficient. Thí:, Llatches lJp vt::ry cluse!,'J '

wlth the dry matter LER of 1.28, Thc i'nferellce, therefore, is that the dry

matter yleld advantage trom the intercrop was due elOtir-.:ly to improvcd eff;--

eJency of conversion of Ilght rather than the int(~r(f';i'i iun of nlorc I ight.

Conslderlng the lncreased LAI af the intercrap, I'Jhicl1 ccmpar"d closely \/irh

the lnereased dry matter, this Improved efficiency af conversion mu~~t h;:.v,

I;>een partly due to the fact that !ight was better liístriuutL-! over more

leaves. There also remalns the pússibi !Ity, uf cnu!"Sl", t.hat SÚrllcJf etw

lncreased efflclency was due to a combinatian af a C3 cror below a C4 une,

~hough whet~~r thlscan actually cause greater efficiency :;ti!l seelii~ :,./ ~;(-

a matter of conjecture.

Figures 6a and 6b show root densities of c;olt, -..:rops .:Jnd intuu\...,p

at dlfferent profile depths Investigated on severo (Ju.J;i'Jns during the

growlng season. In the intercrop I t was found c/lJt the c.omponcnt erer-

'root systerns could not be distingulslled. Hence, dtteillfJts werÇ only n:'ue

to have some comparlson of the tO'lal intercroppin':) r,~()t system lt,iUI t e

respective sole crops. It was found that mlllet (:,(hihited <J rather diff"rv,_

roottng system from that' of groundnut. It was clearly e' ..icl..:nt that ~r' 'J:I<Íí'd

had a more ramified and very detIve rooting sYSt(:i11 Lo;1centrated rnostly in

the top 40 em of the 5011, whereas millet had a dct>(wr rooting system JiSil

buted even up,to 90 em depth. The total root densitl v,~lues af lhe interc,,)p

were Intermedlate between the t,'IO sole crops.

An attempt was abo rnade to calculate 'Lff~' villu::; for rootil,g ,>':r,,,ity

patterns. The I ntercrop tota I root dens i ty Wclj part i ~i úned accol-d i li:; ~ , elC:

proportlon of each crop in the total dry matter; thÍ'i, af course, aSSU,liCS

that the shoot/root distribution is not effectp.d L't illtercropping, \,ljth Lh,s

assumpt lon i t was found that intercrop tota 1 root ciells i ty gave UR v" 1LJl '> UIJ

to 1.18. These values were more or less in line "1;(11 dry rnatter efft.:·~s.

SolJ molsture measurements durlng the grovling pniud indicated no al-'r·rccic'llIL

dlfferences In molsture use by sole erops and illtt:rJúp, though the iiC>U'c

normal rslnfaJI produced wet conditlons throu::jhoul the growing season. i~utlients

were a150 eonsidered adequate. These results SU(;'')êSt that, although ilile,--

cropplng produced a greater root density than thut •..•h i ch v/ou 1d hélve beel1" lexpeç.~d I If there had been no intercropplng effect~, this greélter OUl ; i t Y

was reasonabJy in accordanee wi th the greater dry Illé1t ter produced. ~lLE: re

thus seems little reason to suggest that this reoting effect was the cause,rather than simply the effect, of greater dry matter. There was also noparticular evldence to suggest that the intercropping roet system was anymore efficlent In producing greater growth per unit of roat length.

We gratefu11y acknowledge the valuable advice of Or. P. Gregoryand Dr. B. Marsha11, Unlverslty of Nottingham, U.K., on the measurementof rooting patterns and 11ght Interception, respectively. We also acknow-ledge the help of Dr. Sardar 51ngh in roat sampling and Mr. A.A.H. Khantn llght measurements.

Graln or pod ylelds, total dry matter, and harvestIndex In millet/groundnut Intercropping.

Gra in orpod ylelds

kg/haTotal drymatter

kg/haHarvestindex

%

,,·~te{:grQundnut 1185 5617,Jntererop groundnut 840 3900

L E R 0.71 0.69-------- ------

Sole ..Hlllet 2226 8085.;:..Intererop MI11et 1227 4775

L E R 0.55 0.59-----~- ------

Total L E R 1.26 1.28

SolePearl millet

Pearl lIli lletlgroundnut ; ntercrop

IIIf

, II I

<b IA ?c,9~

I II II fI II II :

Solegroundnut

IfIff II I

<Doif II II II II II 'I !

Figure 2. Dry-matter accumulation in sole groundnutand pearl millet and in groundnut/pearlmillet intercrop on'·Alfisols at ICRISAT Center, rainy season 1978.

/.~...".,: ••.• It'

.,.' :;.:;-" ),.",<;;.-. I

.../'- Exrec ted...;/ inter-crop

,../'.,';( ;,ctual

.:9:'~'k..-ir:tercrOf

'"""",./

",'",;-,r- __,-"

".-I

/I

"C~LJéi l--~/ .I ,.'~

I.... Expec tedI ,.'

I.', ..1 .', .. .

I.', ... "".:1. ; jJ ..'

I;'/:/:

/'1.'

/'/.'

/ ..../.'

.:...:-.~.;;.-~._.,

II

/

Actual,/ ir.tercrop

.~ ....-....

....'/'

/., ~xpcç teu/. (Ir:tercrcp

~ ...",., .....""''''

Fi•••" 3. leaf-area indel ia sole pari millet anel groundllrt and in pearl millet/groundnut intercropon Alfisols atICRISAT Center, rai",' seasorf 1978.~.. '~,

1~-' . I" i

, jiI

!, 1I

IIIIII1

I!I

:

/:":'- .,,' " ""'- ....-.----.

./ ~'" . '\

!:/)' .\,""'-..."-"I I r c I ,

/ "//~.~ ,:

~:~/~' .. /" . .-//:--

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/'/' \

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\\,

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l_o __ "_/ __ ,----,.------ .

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---'1';'

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...•. -... ......•....••. --- -. -...... ...••......•

oVi.t/

--------"'------ "- -~-_._-----._~I

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f"11IR 5. t::rrkiency of conYll'Sion " interceptld lilltt eneru into dI} matter ia sole pearl mlllet and 1I'0UIIdnut •• Inpe.t miliet/groundnut intercrop GIl Alflsoljt·atLÇRISAT Centar, rainy season 1918.

5000ro

..•••.cn4.

L.40CiJ(l)

+.J+.J

E>-c..o 3000

•

"","""

"".•./,,'"~"

~--- -- -'" ~ Pear J mi 11ct/groundnut~~ intercrop..•. ~

Figure 6a. Rooting patterns in sole pearl millet and groundnut and pearl millet/groundnut intercrop on Alfisols at ICRISAT Center, rainy season 1978.

~

,J' , t dén",ity (uni l-I ; )

O 0.5 1.0 1 . ~ Ü 11 . .J. !) 1.5 () (,. !, I. li I r (j d. ') I.ll 1

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20---.c:.•..o. 40eu

"O...•..eu 60..-E

boeu-O (J. () 7 l..'.11! () . L'} rJ. ~ ~V)

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O I. ::. G 1 r O I c' G 1 ['. .) . ) ..)......L.----I-Eu--- 20.c

..~ .•..o.eu 40

"O...•..,.- ='~C 60

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eu 0.06 ú.o8 J. 17 0.21- 100OV)

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1000.07 0.10 0.19 0.28

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Days after 25 3.1'. ilO lj]

sowing

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---0:-'---'-- __o

.Begg, J.E. (1965). The grovJth and develop"1C:it 0'= <) cro,Jof hullu::..n ífíillet(Pennisdurn tvpho!des S & H) . .J, A.1i"ic. Sei. 65:3'il-3!;),____ •__ .-W..- _

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Evans, A.C. and Sreedharan, A. (1962). St.lji.,o, uf inlel'croPfJir.j (; i) (·)storbean with groundnuts or sOY'-lbcan. (:, Arr. J\qric. F'Ji. ,'.

l<assam, A.H. and Stockinger, K.R. (19/3).and mil let in mixed croppln~.

GrV\~tn élfld' ri i t r()'~C:fl upLdí '. 01' 50rghuillSam:1ru l;gric li~\J5'(,tlt:r iS:28.

Lakhanl, O.A. (i976). Crop physiologicil1 :;tu'~y' uf rni;tur,',:; ct ','.Irl' ;~),'.::r éindfodder radish. Ph.D. Thcsis, Li1iv, (A R~(Hling, Enc,Ii:.J.

Newman, E./. (1966). 1\ 1.If=thod of estir,nti'll roté,) 1:~n9th of rr\C;t ir: ,J'x.iilple.J. Appi. Écol. 3, 139-145.

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Schlll1ng, R. (1965). Groundnuts intercrop'~2d ..líth cer~~Jls. Dlc'd:1in:::ux.20. 673-676.

Szelcz, G., Montelth, J.L. and Dos Santus, .J./i (196~). Tute SOI"r"iI7etcrsto measure raJlation amon'j plants. J. Appl. Eco1. I: IV}-l]lf.

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