Agroclirnatological Factors Affecting Phenology of o(t Groundnut \io

C.K. Ongl

Abstract

7hc yuanrrlafrr.e rrspon.st~ot'gro~r~~dncrr l o a rvidr range 01 rrnipcr,~rure, h~rr i i rdr t~ . . ;rntl \or/-unrrr drlk-11s 1.j disc~rrs.srcl in rc1;lrion ro /he clrniatc of' rhr ~rrrii-;rr,tl r rop io (.%:I T). Inlorrt~;rr ior~ ohrilinedfrc~r~r c11nlrol1i.d-cnvrri>~irrrrnl 1acrlilic.s rs rr*.ed to pro\ r(lcSa mod<*/ applrc.;rhlc 1 1 1 rhc SA I I h r i ~ o n ~ e y u c r r ~ ~ c of' irrrg;rlron and r o r r ~ l ~ l l dis/r ihu/ron on i ~ r o l ~ phrno111g~ ;rnc/ rhc perirral rel;iticrn hc1u~ccr1 phenolog\ and j rrld are a1511 clr\cii.r.\cd.

I h r linir/ctl imtbr.rnstron on claj.lcrrgrlr rzspon\c.\ \uggc-st.\ rlr,it genrlljprc I ; I I I ~ I ~ I I I ~ I I\ ;in i r ~ ~ p ~ ~ r ~ a n r lacror orrd rhis I> a11 c~rgcnr arcs tbr rrscarc.h t i u n ~ i d i ~ or w ~ u r a / t o n (lclrc.it does r101

h n ~ r ;I drrccl cllccl on crop phcni~log>. atid wo11/(1 proh,~hl j rr~llcrrnce phcnologj r la rhr u ~ I c r - )deplcrjon r;lrc i n rhe sorl. I)c.l;rj.\ r m /he srart of'rhr r ; ~ i q .scn&orr rrducc lhc Iorgrll 01 tllc yn,\rirrp p i~ r iod u hich rnaj rrsull i n low wj re ldo. 4pror l imnto l i~g ic ; i I I ; ~ L . I I I ~ \ u hrctr ;rftc.c/ crop phcnolopr n ~ : i ~ . ; i l ~ o ha\ c a r r~a/or ~nl lr jc~rr i~c~ o r r g r o u r t ~ p r o c i ~ ~ . ~ c ~ ~ , c>.g., 111 /~~ i r r r ! ron ing o l ~ d r j ~ r ~ ~ d r ~ r r - 1 0 pi)( / \ hj teri~perafrrrr. rhcrcfure. stndrrs 01 phcnologr ;in(/ grourh prucrssrs \ t r ~ ~ u / t l hc, rr~/c-pr.rtr(l rrr ~ , rop-u carhcr invrstigarr~~n.\

Introduction mate. I .~ t . th (1974) restr~ctcd hi5 d e t ~ ~ l ~ t ~ o n 0 1 plie- nology to thc study of dcvc lop~ne~ l l ;~ l t ~ r n ~ n p I r l rel;r-

Phenology is defined by thc Chambers Dictionary t lon to thccalend;~r, while tjuxley ( I9R3) rclegaletl ~t (1981) as the study ol organism\ aa affected by cli- t o a descr~pt~ve study of orpanlsm\ in relarlon t o

ITRISAI ( I n t c r n a l t n ~ ~ a l Crops K r ~ e a r ~ l i I n s t ~ t u t c lor t h e S e ~ n , . A r > d I r u p l < \ ) 19Wh Agmmcle,~~ol~,p\ ot y r o ~ l n d l l i l l Pro~,ccdlng\ < ) I .#!I

Inlrrnat~on, i l Sytnpo*lurn, 21-16 Aup 1985. IC'KISA I Sahullan Ccn( r t , l \ l l r t~ l c \ . N I K C ~ Palanchcru. A t' 5 0 2 324. Ind~,+ I1 KlSh 1

their environment. The first def in~t ion 1s obviously too general. while the second definition is the one generally accepted by crop scientists, and I assume it t o he the one meant by the organirers.

Knowledge of crop phenology is important for at least three reasons:

First, for o p t ~ m a l crop yield in an environment it is necessary to match the life cycle of the crop to the length of the growing season. Such informa- tion is nccded to develop better cropping systems s o that high andl o r htablc productivity can be achieved. Second, the introduction of improved genotypes o r new crops into new regions is largely deter- rn~ncd by tempcrature and phenology (Aitken 1974). I-~nally, phcnology is an essential component ol whole-crop simulation models, w h ~ c h can be urcd to spccify the most appropriate rate and tlmc of \pet:~lic developmental processes t o max- ~ r r ~ i / c y~cld .

I'he lirst part ol this review describes the responses ol g ~ o u n d n u t to temperature, daylength, humidity. ; i r ~ t l r a~ l~ fa l l , and defines, where possible. relevant conccptc . ~ n d pritlciples and their applicat~ons. Later scctlons w~l l deal w ~ t h the intcgratio~l ol phcnologi- cal i~ntl phys~o log~c i~ l informarlon, and linally high- light ;Irr;l\ uhere ~nformation I > needed.

Generalization

Both annual rind pe renn~ ;~ l \pccles ol Arachisoccur, hut the pcrenn~al or indeterminate growth habit is Ino\t conitnun In groundnut (./\rachi, hypogaea I.). H ~ ~ \ C < I I I I F groundnut crops 15 rarcly determined by phyr~o log~c ;~ l maturity. 'The atandard harvesting procetlurr I \ dependent on the degree of defoliation of thc crop or or1 the hhelllng percentage, 1.e.. the pcrcentagc of pods that have mature kernels. L)rought affect\ t h u r l ~ c l l ~ n g percentage (W~llrarns et al.. this ryrrlpos~urn) and weather conditions may ~ndircctly alfcct thc tlcgrce of defoliation through foliar disease ( S r n ~ t h , t h ~ s sympnstum). In the absence ol drought or diseasc problems the heat unit or accumulated temperature Index is the most useful lor predicting optllnurn harvest time (Mills 1964). as well as for analyling otherdccelopmental processes such as the start ol flowering and podding ([.eon$ and Ong 198.1). Var~oub rnethodafor determining the harvest-

ing of groundnut crops have been reviewed by Sand- ers et al. (1982).

Pheriological studies have been more concerned with the timing of developmental processes, i.e.. the start , the duration, and the end rather than with the rate ofdevelopment. The ratcof developmental pro- cessey such as leaf production is usually expressed as numbers per day, whereas events which occur once in a life cyclc, e.g., sccdlingemergence, are generally expressed as the duration (D), for example, for o f the population to reach that stagc. The reciprocal of D is effect~vely a rate and this is a useful way to describe plant responses to temperature, for exarn- ple, as ;I function of rate because the threshold or base ('Tb). optimum ('To). and maximum (I 'm) tempcrature can be detcrm~ned (1;ig. I )

Temperature

Temperature is the domlnant factor c o n t r o l m t h c rate at which groundnut develops (Fartanier 1957, L)e Beer 1963, Cox 1970). In terms ol plant growth and development, the diurnal temperature cycle is more important than tither the regular seasonal cycle o r the random effects of weather in the SA'I ' (Monteith 1977). Even more important for plant processes are the effects ol rnicroclimate slnce soil- surface temperature commonly cxceeds 40°C In

-0.81 x Robut 33-1

0 10 20 30 40 50 Temperature ( " C )

Figure 1. Germination rates for groundnut cultivar Hobut 33-1 nnd Natal Common at various tempern- tures (" C). Base (Tb), optimum ('So). and maximuln ('I'm) temperatures are indicated for Hobut 33-1. (Source: Mohamed 1984.)

many parts ot the tropics, especially when the soil surfact is dry (Virrnani and Sinph, this symposium). I'hc extremes of temperature over a period of day5 or hours may sevcrclv reducc the growth and devcl- opmcnt of many crops. I-or ex;ilnplc. (iarcia-HUI- dohro et al. (19x5) foulld that exposure of irr~bihed pearl millet seed\ 10 5U°C for I I1 rcduccd the gcrml- n;ition rate irnd the percentage germir~atron hy 14(%,. However, similar ~ n l o r n ~ a t i o n is not available for groundr~ut.

Thermal Time or Accumulated-Temperature Concept

I Ilc concept ol thermal time is uit lely uscd lo r des- cribing the temperature re,porisc\ of many crops Including groundnut (Gallaphrr 1979 lo r whcat, Angus et at. l Y X l tor nl;iny (roprcal \pccies. ant1

e l al. 1979 lo r groundn~rt). Hut there IS stil l rrn *# alnty concerning thc choicu 01 hnsc ternperil- ture. Some workers (Weilgola,kr 1974. and A r ~ g u \ r t al. 1981) support the vie* tllat I'h 15 l ~ i g h c t du r i r~g the rrproductive phasc (3-10°C higher) than durillp the vegetative pllasc, and othcrs \uggcat th;r~ 'I 1) i \ 111gIily var~;tblcc\cn tor the stme pl~asc. I n cotltr.l'ir. Ong nrld h~ , cowc~rkers ( O n y IllX3u. 19X3h. 1-cong and Ong IOX3. O r ~ g and Raker I n press) oht;r~rlecl results tllat \bowed t l ~ a t T h IS conservatrvc for the

lnhle I. Bnsr (Tb), 11ptimu111 (Ttr). und r r~~ximurn (TIII) ternperuturc\ of I 4 groundnut culti\ar\

IC(; 47 Kohut 33- I I MV2 MK 374 I'love~ I(.(; 21 M I3 Swallow N Common Kangcr

1 able 2. Vulucsol hmr tcmperuturrs(l h)and thermal tinlc (0) in "('d ut \rveral devel~rprnrnlal protr5cr\ 111 round- nut c v Hohur 33-1. He\ult~ from 5-10 Ireutments.

I)evel(~pmcnt~l prtri.c\s I b ( " ( ) 0 ( ( il) -~

I cal producr~i~n 10 II Sh pel Ir..il Iir;rnchulg J 5 101 pc~ br.inch rrmr to f i t \ ( IIOWCIIII~ I O X 518

r ~ r r i c lo l i rr l pcgglng 10 h (170 flmc to Irr*t podd~~ip

-- --

1 1 3 720 - -

Si~ork,c I r i lng , ~ o d 0 n ~ I V X i

rrl;tr~\i proccssc\ and phahr\ c n i r ~ n ~ r ~ c d (\cc T.thlt. 2 tor gruul~dnut cv Kohut 33-1). Kca\orl\ l o r the app;rrellt v> i r ia t~on ill cxtrapol;~ted \;rlue 01 I h ;ire J~scusscd by 011g and R;tkcr (19x5) V:iluc\ ol I h and thu thermal time ( 0 ) rn ' C ' d l o r e;icli p r t ~ c c \ In 'f;tblc 2 ;ire calculutrd Iru111 ~c \u l t s ;it f i l e trrnpela- turc'i hetuccn me;ln ternpcr;il~lre\ (11 I 9 : ~ n d 30°C'. 0 i c tlrc rccrprocal of the slopc o l the ~ ; ~ t c tcrnpcrattrrc relatiorlship I h r;irlgcd I rom 9 5-1 1 4" ( ' , ul1ii.h I\

c.lo\e to thc \;rlue n f lo"(' u\ed h) Mc('lo~rd ct '11. ( 1980) for the t'NIJ'IS niodel I hc\c I-t.\ults \ ~ ~ g g c \ l that the v;~lue t11 I'h orlc procc\\. KC.. gcrlmn:i- tio11. cotrlti he ~ r \ c d t i1 ~~:iIcr~l:itc t h c r ~ i ~ : ~ ! IIIIIC lor o t h c ~ dc\clopmcnt;~l prt)cc\\c\ 101 each gc.tio1ypt~.

1'1gu1e I illu\tr;ltc\ II1e IJIC Lernpt'lnlurc rel;rllon- \hip for the germl l~at ior~ of tut~ coritra\trng RI ound- nut c t~ l t i \ a r \ (\loharried 1084). I he gc~rnrr~alron (l;~t;r were o h t ; ~ ~ r ~ r d ,I{ con\t;lnI terrlprratuIe\ 115ing a

largc therm;il gradrent platc In \tc.p\ 01 2 - 1 ( ' (;el111 t yp~c t l i l l e~enccs in the rille o l ~ c r r n ~ n a l r o ~ ~ arcgre:il- est ahove 1 0 . hut ;r 0-7°C' \arl;rtrorl III c a r d ~ l ~ n ! tcrnlxl.;lturc\ w ;~ \ ;ilso fount1 For c~';;~rllple. ~ c \ r ~ l t \ ft)r I4 corltra\tlng genotypes \Ilouetl llr,rt I h ranged f r o l l ~ 8-1 1 .5"(.'. l (I from 29 0 - 3 0 5 ( . ;111d 1111 fro111 41-47°C ( I';rhle I. Moharrlccl 1984)

I~crnperatr~r-ca close hr I 11 ;111tl 1111 ~ r ~ ~ ( i u c t . :I lo\\ rate of gcrii1rll:ttrorl ( I<g), ~III l11t.11 I I I ~ ~ ~ I ~ I I L Y OII I IN~ proport ion 01 bccds wh~c l i II~I'III\ ~ C I 111111.1ttxl I 1111) I\

~CI I~ I~~PICXI I (IC~CII~CII~ (I-I~. 71 to^ c\;trt~ple, (1111

o fcv M;ihulu Red. ;I Ilighland I \ r r ~ ~ r c h nlolc s c r ~ \ i t ~ \ e to a reduction In K g e;ii~\cd hy Ihrgh ( .2X.SUC') rather than hy l o u tcnlpcrarurcs. I h ~ \ genotype is theretorc poorly adaptrxi to 111gh terll- peraturc\ ccrl~iparcd to cv Plover. ,I Hr;i/rli,t~~ pcno- type. that 19 not grcatly aftccted u l ~ r r l the tenlpcrir- tur f lcaches40.5"C. l 'hs sc.lcctron for ;I heat-toler;~nt groutl t i r~ut cult~\;rr 1s Ihc rc lo~c po \ \~h lc I r l m;tny t rop~cal reglolls *here so11 tcmllcrature\ rcgul;trl\ exceed 40" ('.

P l o v e r

1 .0 - 28.5

0 . 5 -

Makulu Red 3 6 . 5 _I: 4 0 . 5 v d r i e t y ) ( h i y h a l t i t u d e

+~7----, 0 0 . 5 1.0 0 0.5 1 .0

R a t e o f g e r m i n a t i o n ( R ) 9 4thr

14

I.igure 2. Relntion\hip o f n ~ n x i m u m germination and rate of germinntion to temperature ("C) of groun2%ut cultitars hlnkulu Red and Plover. (Source: Mohamed 19x4.)

Flower ing a n d ( ; rowth

Work 111 g ~ o w t h c ; ~ h ~ n c t \ ( t o r t ; ~ n l r r 1957) shows that tlrc fluwering and growth rc\pon\e\ of ground- nut cv Schaar , 21 to tcrnpcrature are remarkably sim~lar to tIl,~t dcscribcd for gcrnl~nation (Fig. 3). I lie optlnluni tcmpernturc lor hoth processe:. Ileh betucen 32-34"C', whict l~s C O I I ~ I \ ~ C I I ~ with the valuch reportetl lo1 germlnatlon 3rd brar~chi~lp(Mil ls 1064. 1)e Beer 1963). 7 he flowering ufgrourrdnut docs not rndrcdte ilny thermoperrodicity ;rnd most species arc day-neutral (Fn r t an~e r 1957).

I'hcrc is littlc informat~on o n the effectsof ternper- ature 011 the phcnology oi groundnut in the tropics. W~ll lams ct al. ( 197.5) reported that the growth of c\ Makulu Kcd varied at rrlcan air temperatures of 18, 20, and 23°C. Crop5 were harvcstcd when 95% ol their lzaves were lost by natural defoliation o r until 70%) of the pods had matured. l h e total growing durations lor these crops were 176d at l Xo ( ' . 17hd at 20°C. and 1.51 d at 23OC'. Growth-analyhis results showed that only the 23'C crop reached physiologi- cal maturity, 1.e.. total pod dry weight reached con- stant valuc and cs t~matcs ol thermal time (maturity index of 2000°C d and T b 01'8.5~C) indicated that the two other crops were harvested at least 68 and 15 d earlrer than the 2J°C crop. It is possible that the

low ternperatut.e or disc~rac bu~ ld -up rliay havc cdl lh~d thc substaritiaI foliage lo\ In lhesz c lop\

At IC'KISAT Center (17"N) the mean air tempcr- atures during the rainy and pohtralny seirsons arc very diffcrcnt. 1)uring the rainy cajon (.lun-Sep) the mean air temperature IS 2Y"C' for thc l i n t 0 weeks

00 1 10 2 0 30 40

Mean a i r temperature ( " C )

Figure 3. Hate 9f flowering (1/1)) of groundnut cul- tivar Schwarz 21 as a function of mean air tempera- ture (' C). Recalculated from Fortninier (1957). D is days for 50% of the population t o produce the first flower.

and declines to 26°C for the reruaindcr of the grow- ing pcriod. In contrast, the mean air temperature during the early poatrainy seirson (Nov-Pee) is about 21°C' and increases s tcad~ly to 2Y°C in April (ICRISA'T I984 pp, 1x3-185). Since plarrt develop- rnenl 1s prrdom~nant ly controlled by ternpcratlire there areconsplcuous differrnccs in the tirnc to flow- cring. podd~ng . arid the total durat io~r ol crop growth in the two seasons ( l able 3). hesc results were h;ised on act~~alohserv;itionsol 'cv Kob l~ t 33-1. and are consistent with calculations hased on ther- mal time (niaturity indcn o i 2000°C d and 'r ol lO"('1

Daylength

Larly str~diea in growth rooms h o w r d that the phr- nolc v ol grountlnut IS not allected by daylength ( , ; q i e r , 9 7 5 ) tiowtver. recent rese;~rcli tias i n d - catel that pod yicld i\ greatly rr\!lurnced by day- length (Wytinc and Emery 1974. Ketring 1979) and genotypic variatron in yield r rpon 'es to short and long days has been repol led by Wlt7enbergcr ct al. ( In prcss). I Ile last group of wot.kcr\ reportcd ylrld incrcast\ of 36-1065 undrr short clay\ ( I 1-12 h) In four culti\ars but slightly ~ncrcascd !leld in lorig days (15-10 h) ill the rematning tM0 cultivars. 1 he difference\ I I I qicld responses to daylength arc mainly tlur tochanges 111 rhc numher arrd proporllon of largc kel-nels. Clearly. there IS arr urgcnt need to ideutily daylength ser~silivity 111 tile exi\ting gernl- plasrn to match a spscificdaylengtl~. cspcclally when e x o ~ i c cultl\,;~r$ ;ire grown rn new leglons 01- when two crops are grown withir~ a )car In regions of high latitude.

It IS well estahl~shed that lotig day\ promote veger:ltivt: p rowt l~ , e,g.. i~rcrca\etl sten1 Icr~gth and

Table 3. Crop phenvlopy olcv Hohul3.7-l rainy and pwt- rainy seasons, ICRISAI' Center.

Po\Ir'tiny Growth stage Ra~ny seaon 5cason

. . . . - -

Day\ to first llowelirrg 24-26 40-44 1)ays l o pod filllr~g 52-54 80-X.I 1)uration ol pod fill~ng (d) 60-64 60-62 I,c.ngth ot'growtll ( d ) 110-1 15 1.75-140

or 2000" ('d -- . . - . -- -

Source, l ) ~ ~ c l h d r . ~ l n p u b l ~ ~ h c d

leal growth at the experisc of reproducti\e growth (Ketcllaper IYhY), hut therr I \ some uncertainty about the influence of daylength on thc d u r a t ~ o n of reproduct~ve growth. In a atutly of sebcral cult~vrirs Sengupta et al. (1977) found that flowering was delayed by a davlctigth shorter o r longer than 10 h, whereas in contrast. K e t r ~ n g ( 1979) did not o h s e n e any effect (11 daylet~gth (8. 12, 16 h) on flower initla- tion. 140th the$e worker\ used diflerent cultivars In their experiments and it is possible that genotypic v a r ~ i ~ l i o n I I I rcaponse to diiylength miry also be Irliportant.

Humidity or Saturation Deficit

Satur;~liolr dcl ic~t ( S l l ) i\ an Important ; igrocl~rnat~c f:~ctc~r because 11 1s :I 111aior (leterriiirrant 0 1 p~tcrllial cvaporatlon In many clirr~;ite\. S1) nor ntl i~rdc- pendent \ a ~ i a h l c , hut is clo\cly cuuplcd 10 the tairl- fall and tempcr;i\\rre. Groundnr~ t crop\ are oftcn irrigated or grown on stored molsturr dllrrng the postr,lrriy hca\on wlicn S1) cxcecds 3-4 Kl'a. It I \

~ ~ a u a l l ) ~mposslhle to conrrol SI) c l l cc [~ \c l>~ ill tllc field. $1) ph!aiolop~cal \ t ~ ~ d ~ c h 01 S l ) l~:r\c hccn res- trictcd to ~o111roIIed C I I V I ~ I ) I I ~ I I C I ~ I \ Hc~xt.ver. not r n l ~ c l ~ I \ kliowrt ahorit thc ~nllucn'r ot SI) on the pllct~olop! oI gro~indnllt hec;i~i\c : ~ t t c ~ r t i t r ~ ~ ha\ heen ~ I ; I H I I to thc corrscrvalrvt' \ \ ' ;I! . that \10111~116 re>porrd 111 S l ) t o I~rnit tlic actual riite t ) t t rdn\p~~-; l t~or l (Hlacb and Squlrc 1079).

Sa tu ra t~on cfcliclt rn;i ha\ c 311 e;~rI! ~ I f cc t O ~ I crop e s t ah l~~hrnenr h! 11) direct ~nI'l\ici~cc on the crapora- tlon 1 ) 1 jcctl-hcd mo~s tu rc t o r c\aniplt.. ~ o r k In controlled-cr~\~ionrnerit grccrrllousc\ \bowed that sccdl~tlg cstirhll\hmcrrt 01 prourrcl~r~i! drcl~ricd by 20''; whcr~ tlic rn;ik~rr~rirl~ S l l ir~crcascd 11-orii 1.5 to 2 5 Kl'a (Orrg ct ;I] . 111 prcrj). OIICC the pl;~rlts arc full> c\~;rhl~slicd the rnllucrrcc 01 S l ) I S dcpcndent or1 the I.:IIC 01 water uptahc h! the roots, rlie fn l~age atea. ant1 tlic sorl-moistnrs L,ontcnt (S~rnnnundb and Oiig. In p r o s ) . I hc intcracllon hct\rren S l ) and the watcr-htor;lpc c,ipacrty ol thc \ o ~ l urll oh\~o?~sI!. hr a nlrllc'r factor In detcrrnining H Ihe11ie1 crop p l~eno l t~g \ is allected. In add~ t ion , the cat I? plrcrlolog~c;rl s t a p and procch\es durrng carly growth arc less I~hcl) 10 he affected than thc late prclce\ses auch a \ pod filling. Fo r instar~cc, the <tort ot'tlowcrrng ol c\ Kohut 33- 1 15 ~~lra l lec ted hq tnrall S f ) Idrlglng Ilo111 1.0 to 2 5 KP;i (Orig ct al. In press). ' I he 111Iluence of SI) on crop growth and phenology w~l l contlliue to he poorly understood unless rnorc con~rolled-cnviron-

tilent I ~ C I [ I I I C \ are abailahlc to \;irk the S I ) and the tcoIpcraturc d~urn;llly i t 1 tlic 11:1tura1 cII\Iroilnicnt.

Rairllall ir the n ~ o r t \ignilic:~r~t c l ~ r n a t ~ c f a ~ . t o ~ allocl- ing c ~ o p p r o d ~ ~ c t i o n In the S A l hccau\c niost crops are ~ -a~nfc ( l A Iou and liighl) bar~iihlc ra~rlf;ill couplcd u ~ t h roils of low uatcr-hol t i~r~gcapact ty arc c ~ l c d ;I\ 111c 1llii)01 constraints tcr cl-op ploductioll In thew rcpions ( V i ~ r n ; ~ n i and S ~ r ~ g h . th15 ympoaium). hut thc rcl;tt~onrtlip hctuerrl g r ~ > u n d ~ l u t ylcld ;inti

\ea\o~l;il r;~ir)t;~ll ir c~tten pool (I'opov I1)X4). Figure 4 ~l lu \ t ra te \ the highly \ariablc yields in Barnhey. Senep;tI, h e t w c c ~ ~ 1932 ant1 1964. iind \how\ tour- lol(i change\ ill a \e;ihon;ll ruini;lll of XU0 nlrn. Slrrl- ilarlk, groundnut yicldk ;it I( 'KISAI ('cnter arc ~ I O I I ! cor~eliitcd u ~ t h total r;~lnf:ill ;tild there I \

cons~dcr ;~ble variation in thc har.ve.;t irldcs ( ' I able 4) It 1s rlnt clcar whctllcr such > ~ e l d 1luctt1;itions arc due to tllc d i r t r ihut~on ol r;iinf:ill. waterlogging. or the niagrr~ti~dc ot tlir d~ \easc d; i~nagc

1 ;:

0.5 I l e l . * l , , , * ,

400 600 800 1000 1200 Seasonal rainfall (rmi)

Figure 4. Comparison of groundnut yields (t ha-') and seasonal rainfall for 32 years (1932-1964), Bam- bey, Senegal. (Source: Popov 1984.)

I ahle 4 ( omparlson of pod yield (t ha I ) and harvest index of groundnut c \ Robut 33-1, I ( HlSA r Center. rnlny sea- *on\ 1978-1981.

Pod yield ( I ha-I) -

1.19 3.00 1 7 0

4 41

I h? 2 44

- --

Hiirvc\r index

I lic Inlp~irtarlre 01 ~ r t~n la l l d~st r~hut i r rn reground- nut yield i \ ucll ;~ppr.eclated. hut expcr~inentaj,ebi- dcnce IS poorly docurnentetl. In Oklahom'~. WtlM~ck ct ; \ I . (1961) rcp~)r ted a yield of 2.7 t h a ' with sup- plt.mcntar> irrlgatitrl~ o f75 Inn1 on 21 July. but otlly I .X t ha-1 wlien the rarne irrigation was i~pplied on 31 .lul?. t.ew drought htudlc, h a w ntternptcd to d i s t~n - puisl~ the effect of the amount, Irequency, and the d i s t ~ i b u t ~ o n of rair~fall on gl-oundnut yicld. Work in controlled-erlvironrnent greenhouses at Nott~ngllam linivcrsity. I I K . rhowed yield which was four times greater than thc yield of crop, wl l~ch used the ramc amount ol water, hut w a i r t~gatcd d r~ r lng the vege- tative phase only ( 0 I ) A 19x4).

A severc water dcl'lcit can delay the onset of flow- ering ;inti rapid pod growth (Rills/ and Ocha 1961, Hllla/ IYO?). Y~eld 15 often reduced by drought evcn uhen plant stress is relicvcd by irrigation because pod maturation is delayed, and 11 15 not always pos- sible to drlay harvesting. Hoote and Hammontl (1981) reported a delay ol I I d In flowering when drought wa\ imposed between 40-80 diiyr aftcr sow- ~ r ~ g ( D A S ) . Stansell and Pallas ( 1979) found tha' 4.e

pcrcentagc of' mature kernels of :he saine cul, dr '

was reduced to only 34Y of thc control when drought was ~nlposed 36-105 [)AS. Uetailed intor- mation on the irrigation. water use, and water rela- tions of groundnut is reviewed by Boote et al. (1982).

Integration of Phenology and Growth

Agroclimatic factors that influence crop phenology may also have a major effect on crop-growth rate

;rrld t l i r partltlolllnp o f d iy ~iIi!,ter. I t i \ u\cl l l l there- Iorc to Iritcgl;ite p l rcr~olop~c;~ l and growth re5ponsc.h For eu;~r~~ple. te~ i~per i~ tu rc allectrd thc dry-nlaltc~ protluctlar\ of pearl nill let hy povrrnlrlp rhe r;lte o l l u r r r l a t~o~ i and the dur;~t ion ol canop! ratllcr than the ~ I I I ~ I C ~ C V 121 o l a r tnerg! cori\cr\lc)n ( S q u i ~ c ct al 19x4). A arrll~lar ;rnalysir of tht. rnlor nlation on

p ~ t i u n t l n u ~ 5liowh that the d u ~ , i t ~ o n I ~ o m \ouir ig to theerrtl o l pod l ~ l l ~ n g ( d r l ~ n e d a\!OOO"Cd) increa<etl r o d at I ' ( ' t o 2 2 2 d ;I! IO"('(I.lg. 5 ) . 1Irlp11h- I~shvd dat:r (H M;~rshall. Nt ) t t~ngham Ilmvcr,~ty. prlsorlul con1111~1lrcatior1) \hl)u.s that r;lpld canop) l o ~ ~ n a t i o r ~ \tai ls at 300°(' d ;III~ rcachec canop! c lohu~c at XO0"C d at a Ic;~l area ~ntlc.: ( I A l ) ot 3 A\\urnlng ;I rllaurnirlm g rvu lh rate of 20 1: m .' d ' (1)unc;ln ct al 1978) ;it all ternprratulu\ tor the rcrn;~ indc~ ol the prohlr1K per~od. the total dry- mattel. p ~ o d u c l l o n 1s L2.X \ ha ! at ? \ ' ( ' and 32.2 t ha 1 ;I( 2 2 ' ( ' ( F I ~ 5 ) . l lou.t.\rr, l ic ld ohher\:~tioti \Ilo,-that 1I1c c r o p - g ~ o h l h rille I\ 111ucrcd h? teni~lar;rtItre, heion 23°C' (Wll l ianl\ cf ;11 1075. I t i r

Mahulu Red) arltl LIIC tcltal d l ) ~ r ~ i l t t c ~ I\ ieduce(I hb O(l(', ;it I X " ( ' antt 40"; ;it 2 0 ' ( ' ( t .~g . 5 ) 1 Ilc cftccl ol 111gh t e ~ n p ~ ~ ~ i i t ~ ~ r c ( 31°C') 1111 c r o ~ ~ - g ~ o ~ t t i rate I\

1111k11oun alth,>ugli thc appalcnt ~'hr~ros\ntIirhi.; 111

- Dry r r ~ a t t e r

D u r a t i o n ----- 3 C l - Dry l n a t t e r when c r o p

growtl! r a t e a f f e c t e d

Temperature ( " C )

Figure 5. Temperature rlfrctr on the duration horn sowing to end of pod filling and the final dry matter produced. 'l'he duration i s calculated using a matur- ity index of 2000" C d and l'b of 10°C'.

~ n d r \ ~ d u ; ~ l Ic;~rc\ 15 ~cduccd h) 2.51, uhcn tcinpcrcr- turc lricrt;1\e$ t10r11 3 0 to 40 ' C ' ( I~\I;I~\:II-I 19741

Ie i~ lpcraturc al\11 ha\ a prolotrnd cllcct on thc part i t lonlng ni dl? mnttcr r o pod, i n ground nu^ (C'ti\ 1970. 0r1g IVX3) I ' od -g~ou th rate 01 I.lurr- giant groundnut I\ reduccd h) 45' ; uhcn the tcr11pcra- turc I\ I I I L , I ~ : I ~ ~ ~ Iron1 24 'C' t c i 3 2 , ( ' ;irld t t ~ c 11r1aI kernel we~pll t i \ r cd~~ced by 30'; ( ( ' I ) \ 1Y7Vl I he np~ i rnum ternpcri~turc lor pocl i c l d ~ \ t h c ~ e t o r c c ~ i ~ ~ - \ i ( l e ~ ~ ~ b l > 10ht.1 r1i,111 t t ~ t i t l o r the r.11~ of dc\cIoprncr~- ral proce\\c\. Rohut 31-1 \\,I\ ,in optlmunl rclnpcrn- t u ~ c for pact g ~ o u t h ol 24°C (Ong 19x4) u l l i ic Makulu Red lid\ 1 o ot ?(I-'( 1\4illr,irr1r ct ;I]. 10731. I IICIC arc \r\et;ll other rc;isc)Ii\ u l i > h ~ g l ~ c r ten~j>er ;~- lure\ ; l r cdc t r r~~~cn ta l t o ~ e p l ~ i l u c l ~ \ c pro\btll. pollen tle;~th IS ~cpor tcd 11) o c c u ~ at 13 ( ' ( 1)c I k c r 1963). Iewcr pep\ ;111d pods i i ~ c produced: glcatcr \ten> g1-11u th rna? c~inlpete dlrcctl) \vlIh rc[)rot luct~\e o~-gari\ tor ; i 5~1n i1 Ia t r~ ( 1 o l t~ inrc l lCJ57). <111d tii l l \ t c i~ r \ Il ia> IMC\CIII pcgh I ro lu 1cac11111g ~ h c p o u n d (WIIII~III\ ct ;\I. 1975. 1 corip and O n g 1983).

High \o11 tcrnpcialure ( .30'C') m:1\ ;II\I~ he ,III Irrlport;int I r r r l~ tat i~ in l o ~ I O L I I I ~ I I I I ~ pod )reld 111

r r~uch of ~ h c SA I hec:~u\e IoL.;II hcar~np ot tllc pol l /one rC\ultcd i n rn;ijor ~ c d ~ ~ c t l o l l In plld b~c ld u l ~ c n tcmpe~aturc cxccc.ded 24 ( ' (I)rc!c.~ ct al 1981 1.

Daylength and Saturation lleficit

I herc I\ ;I dearth ol inlorrn,itior~ on 111c effects of tllc\c lacto15 or1 thc phcnolog~i.aI arltl p r o ~ t h resporlsc\ ol gr111111dnut /I\ preciously p o ~ ~ i t e d out. rllc Irnpor- titnce of d:~\ i lcr~gth on plirncilogy and >lel(t I\ proh;r- hly depcrldcnt 011 carrcl!. Worker\ ;II lC'KIS/ZI Center ;II~ ~ n t e s t ~ g n t i r ~ p [hi\ ;I\prct.

Sntul-;~~ion detlcit h i l l ha\e ;I maior cllect on thc hater-use ralc n r ~ d Ihc g r o ~ ~ l i 01 g~oundnu t ~UOVVII

on stored n i o ~ s t u ~ c . 1 he w;ltcr-uhe rftlcrenc\ (WI IF I , dcfiricd a\ the amount oI d ~ y Intlttcr protluced per urli! o l w;lter t ~ a n \ p ~ r e d . I\ ~n\erscly propor t~onal to SI) (S~minor ld \ ;~n t l Ong I n picah) hul ~ n u c h Its\ IS

known about the way In w h ~ c h dry-matter protluc- tron 15 related tn SO. Work In controlled-cnvii-~IIIIICIII grecnhouac\ \how> that IirrgCSI> ( , 2 . 5 Kl'n) accel- erates thc tleplrtlon of soil-molsturc rc5crvt.s and greatly rcduces L A 1 hy lower~ngt l lc turgor potential of the cxpanding leacea (Onp et al. I n pres,).

Hecnu,c cxpanding Iravc.5 are more \ens~tive to nlolature deficit than pod\, the p a r t ~ t ~ o n i n g of dry rrlatter is l~ke ty to be aflected by SI). Fo r instance. comparison 01, the rates o f peg production and leaf expansion at lour levels 01 SL) shows that pegs arc

12, - L a t e cultivars differ widely in their recovery when

20 40 60 80 100 120 Days a f t e r sowing

Figure 6 . Compnri\on of the dry-mntter production (t ha I ) of ground~~u icu l t i va r Rohul 33-1 with cnrly and lntc irrigation. Both crops received the hame amount of irrigation. (Source: 0 0 i Z 1984.)

rclali\cl! ~i~iaI'l'ci.ti.J h) drought stle\\ 11nt11 prcdauri watci potcriti;ll ~eachch -0.8 M l'a (t'lp. 6).

I hese o h \ e ~ \aticlris aic con\lstent wlt l i tlic f i nd~ng that when the rnajo~ riiiks t i l e wnaitive to u;iter def~cits, dry rriatter is prelcrenllally distributed to other parts ot tlie plitnt (Wardlau 1969).

Ra in fa l l

I n contrast to the poor correl;ltton between the arnclurit of ra~n la l l arid g ro~~nt lnu t yicld (l.ig. 4. I'able4). field studiesshow that yield is proportional to tt,e amount of water appl~ed wher~ rainfall is low (Bootc ct at. 1982, for review 011 irrigation effecth). The postraiiiy season at IC'KISA I Center provides an ideal rain-free environment to study the interac- t ion between phenology and drought. Re9ults from a serier o f experiments there ( ICRISAI ' 1984) show that:

early stress (29-57 D A S ) does not influence pod yield greatly, pod yields are increased by 15 g m-2 cm o f water applled 93-1 13 [)AS, i.e., seed-filling phase, cind

drought stress 1s relieved (Williams, this sympo- \ ium).

The analys~s o l Kowal and Kaasam ( 1974) illustrates the strong connection hctwcen the length of the growing per~od (asde te r~n~r~cd by total rainfall), and the ~ i e l d of a 120-d groundnut crop In northern Nigeria ( ' I ahlc 5). The delay ~n the alart of the rainy season witt i increa$inglatitudes reducestlie length oi the growing per~od, which results In lov,cr yields when the growllip per~od 1s Iehs thari 90 d . 'I his analysis highlights the Irnportanct. ol the interactioi~ between plisnology and the rainfall pattern.

The 1rnport;lncc of variat~on In rainlall distribu- t ion oil g r o u n d n ~ ~ t yield 1s not well understood bccau\c rcscarcl~ has concentrated on withholding watcr at dil'fcrcnt times of thegrowingacason (Pallas et al. 1970. Starlscll ct al. 1979). Ilntortunately, In man) of thche experiment\ the ainourlt o f rter applied changed w ~ t h the treatment so tt "'he cffccts due to the timing and amount of watdr ap- plied could not be separated. I)etalled analysts of thc expcrirncnts coiiducted at Nottirighain University ( 0 r ) A 1984) shows that the dry matter ciccumulated hefore pot1 f i l l ~ n g 1s not avail;ible l o r retranslocation to pods anif thc part i t ion~ng of \uhsequent assimi- I;ite\ i b unaSICctcd by tlie treatmentb. The crop5 w h ~ c h received early or late i r r igat~on used the same amount of watcr and produced the same amount o f dry rnattcr, but loss of' leabcs wa\ observed In the late-irrigation treatment only (Fig. 7). I'his experi- rncrlt dcrnoiistrates the substantial effcct of rainfall d is t r~but ion on groundnut yield and provides one

-- - ~

Table 5. I he effect of variation in the length of growing period and rainy reason on groundnut yields with latitude in northern Nigeria. &

Length Lenglh . . of ~rainv ot growing Latitude Y~cld ~eason (d) per~od (d ) ( O N ) reductic~n (76)

1 1 5 120 1 1 2 0 l lo 120 1 1 2 0 109 1 20 I1 2 0

YO l lo 1 1 3 0 80 1 00 1 1 5 R 70 90 If X 28 60 80 12 0 40 SO 70 12 1 56 - - - -- - - - . - -- -- Cuuric K u w d l nnd Knaaurn I974

PCLJ (11 Oc'dct 1 or1 - Leaf vexpanslor1

2.5 D 3 . 0 D

Iqigurc 7. Helationchip hetween predawn leaf-wntrr

potet~t ial ( MPa) and rates o f leaf expansion (cm7 d I )

and peg production. Treatments are identified by the

m a x i r r ~ u n ~ \aturation deficit (KPa) and the coil

1 regime: N for wet and I) for stored rnoi\ture.

* c~p lana t io l i for the large var1;ttlnrl In the harve\t

Index ob\er-~cd Irorrl year to )e;ir ( l ahle 4).

Further u o ~ L I\ llecdetl to dctcrmilrc u l i c the~ the oh \ r t \ cd p;ittcrli I\ typrcal t i t the rr\[,tin\c\ to the varlatlorl In r~i111Ial1 d r s t ~ t h u t r o ~ ~ . I hcle 15 ,t po\h ih~l -

~ t y t l l ;~t cir l t~\;rr\ that h;t\e the ;~hrl i t> 111 ~ t t r a n \ l ~ i -

catc r n u c l ~ o l ~ h r htorcd d l \ rrlattrt to pod\ v+oultl hc

Ic\\ \rnsrtr\c to va r r ;~ t~~ in In ra~nfa l l ~ l r \ ~ r ~ h u r l o n

('onclusions and Research Needs

no ~ r l l o r r n a t ~ o n (111 whcthcl h ~ g l l tsmpe1;iturc (-'-.40"C) in1 only :I lew l ~ o u r \ 111 tllc day ha\ ;I nialor

ellect on crop developn~r:nt. I t i s c\ldcrlt that 111gh 4 ro l l tclnpelaturc\ can reduce aeedl~ng esti~hlr\hrlier~t

and litnit reproductive yield in marly areas o l the

, I@ cs. I.ahorntory studies show that \octrcch 01

rc. . tancc lo high or low temperature\ exist i n the germplasm (Moharncd 1984). and t t~c\e cultivnr\

should beutilized to cnaure better ylr ld atahllitv I t I\ vital that agroclirnatologihts collrct ~ntorrnatiot l on

soil temperaturc throughout thegro~~ndnut-growing

areas to predict the phenology o f grtrundllut. Differ- ences i n microcl in~ate may explriin the reported dif-

ferences in the yield of sole and intcrcropped ground- nuts (w i th a tall cereal sucll as \orghurn) during tht. dry season. llnpublished data show that hl iad~ng b!, the sorghum leaves reduces the temperature or rhc

groundnut lcaveh by 5 - I O ° C ' during the day.

Kucent studlr\ at ICRISA I ('cnte~ have dernon-

ftratcti the Irnportancc ol ge t~o t )p~c differences in

the hcnsltivitv ot groundnut > ~ ' l t l \ toda>length. I he

elfcct of d a ~ l e n g t l ~ on the du ra t io~ i of the reproduc-

t ~ b c phase I\ \ttII uncert;liri and lurther work I\

rlcedcd to assch\ the cxtcnt l i t gcnrtlc \ a r ~ a h ~ l ~ t y .

S;tturatro~~ d c l ~ c ~ t IS l ikcly to aflcct thc d u r a t ~ o r ~ of

late dc\c lop l r~c l~ta l stage\. SO interaction wrtll ~ o ~ l -

uatcr contcllt \Iioultl hc e\:irnllied I i l r ther. Such s t i ~ d ~ c \ mu\! be cal I led uut 111 co t i t ro l led-cr tv~ronmrr~ t

grccnhouhc\ \11 rI1;it tlie S l ) driti the rcrr~perriturc can he \;~rrcd t l ~ ~ ~ r n ; ~ l l \ a\ they do In ll lc n;itul:il cnb1-

rorinicnt. I lit. ~ntlui.nc.c 01 r a~n ln l l cln g~ourlt lnu! > ~ c l t l \ I\

ccrrriplcs bccau\r of I[\ ni:llor cllect or1 the p;lrtltlrrn- ing o l clr? Ili,ttrcr. cli;irlgc\ In pod rn;rtul.atron, and

thr ~llcrtltlncr ill I o l ~ a ~ d~s~. .~\e\ th,it rn;i\ lnucr L,rop

grout11 rate

I.rn;~lly, progre\\ III u r ~ d i . ~ \ t a n d ~ ~ ~ g crop-~eat l lc r

lel~1tlol l \ l l lp\ rlccc\5lt;ltc\ a L.Ill5el lllti.gl:i1lorl l l fc~ l l lp plierlolop> and grout11 rcsporl\r5. I .or c\;ilnplc. I hr

\~ l r v r \a l or Irnal r t l tn~brr 01 gr:llnr pr~itluc.ccl in nia17c*

a n d m ~ l l c t IS dependent r i l l tlie g r ~ i u t l i !;ire 111 lhe

uholc pI;111t a \ well ;I\ on tcmper stlire I I l ,~uLrn \ ;tnd ('oilper 198 I . Orrg and Scll~rrc 10x4) I l ~ t . c ~ i r ~ c c p t ( i t ,I thermal p r o a t i ~ ratc h:r\ p r ~ i t c d usclul 111 r~ndcr-

\talltl III>\+ \:<Id corriponelltr itre dc~crrn~ned III

ccrcal\, allcl 11 \hould ht. e\;~lu;itcd fcrr g~o~r r idnu t .

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Mohamed. H.A. I9X4 b ; ~ ~ ~ e t i ~ l t l~ l lercnrr \ III tile renipr1:t t u ~ c rc\potisc\ (11 gcrlrlin;itlon ;tr~d crop ebt;~hl~shrncr~t 1'11 1). l l ~ r . i ~s . \ I t~ t \c r \ t ty cil Y<IIII~~II~IIII, \<II[III~\I~~II, \ ! K

Monteith. J.I.. 1977 ('111nate I';tgc\ 1-25 irr t cop l~) . \~o log 111 ttcip~cal crnp\ ( A l \ IIII, I' I , <i11c1 ko/lc)wak~, I ,T eda.) New Yot L . 11SA A i a d c n ~ ~ c I'r.

Onp, C.K. ll)X3;1 Kespon%e to tcnipcraturc 111 a \ t ;~nd ' pc;irl tnlllct (P?r lnf i r lun~ !,phortlc.s S, 6i I { ) . I Vcgct;il~v ~ i c \ r l opmc r~ t .Ioi~rr~;tl 111 L ~ x p c t ~ ~ ~ i r n l a l Hut;i l~y 34 122 736

Ony, C.K. IYX3b. Kr~ponse to tctl1per;irute In ;I \ta7 & pearl 1i111lrt (Prrrnrscturn typhoidcs. S. B H). 2 . I<cpr(. , . tire dc\elopnicr~r Journal of Fsper~rr~cnt;tl Rotany 34:377 348.

Ong, C.K. 1984. I hc inllucnce of tcrnperature and uatt dcficits on t h t parritloncng of dry matter In groundnt (A rach r hjpogaen 1 .). Journal o l T:xpt.rtrnen~al Rotar 154:746-755.

Ong. C.K., arid Baker, C.K. ( I n prc\\.) Tcrnperi~ture ;in leal growth. In Control o l Ira! growth (Baker. N H L)avies. W.1) . :ind Ong. C' K.. edc.). Cambridge, I J I Cambridge l i n lw ra~ t ) Press.

On& ( .K., Hlnck, C.H., Simrr~orrd,, I..P., ,~ntl Snffrll, H . A . (111 l i~e \s j ln l luc~iccol <:rtrir,it~tiridcI~c~t 011 1c;iI p r o d ~ ~ c t ~ o r ~ and expansr~rr~ In st.ir~ds c!l g ~ ~ r u n d n l i ~ (/ti;ci.hrr Irj,pcly.~c~ I . ) g ~ o ~ ~ i w1tt10r11 rrrlgirtlon. A~ir i i i I \ 111 Bot;in>

Ong, t'.K.. Simmond*. I..I'.. 'Terry. A,('.. ar~d Matthew*. R.M. ( I n p ~ ~ h \ ) Kcsponre to \;itusation t lc l lc~t In ;I \tand of gro11n~111ut ( .\r;lchr\ Il!p~!yac;~ I. ) II (iruwth and (ieveloprrre~~t Ar~r~a ls o l Rotan)

Ong, C.K. , and Squire, ( ;A . lYX4 I~t'sl!~rnhr 111 tcrnpcr,l- t u ~ c 111 ii {tand 0 1 1ie;irI rr111Iet ( l ' c r r i ~ ~ ~ t ~ t r ~ n ~ ~~/I/~~IIC/C,~ S & t i ). VI1. ihrral ncrrirlier crf >plkclct\ drld gr,rrrl\ Iournal ol t xpe~rnirnt ;~l 11ot;111\ 15~123~-1?40

Ong. ('.K.. A I I ~ Baker, C.K. 1'1x5 I rrn[icr;lturc .111d lcitl g ro \+~I i I';~ge\ 176-200 i n ( '1111t1ul 111 leal g r ~ i u ~ h (H;rkcr. Y.K , I);I\IC\, W 1) , ;III~ OI I~ , ( ' K , c(l\ j. C' : is~~h~~i lgc. 1 I K ('srnhl-rdpc I :~ i r \c r \ i t y IJrr \ \

G.F. 1083. ('I~II' r l i on l l ~ r r r r~g ;~s~~ l IO I~C~I \~ I I I~ I'<I~I.\ rn . \p~or r lc tc~ !~o lop ( 1 1 \ r~~g l l r~ r r r arid 1111llcl 111 t l i i .

r c l r l l -~ l id troprci proceeding\ (11 tlic ~n tc r r l~ r ron.~ I \!Inpo \IIIIII. 15-20 \<I\ 1982 l<'l<lSA I <'c,~~tcr, 11id1:1 f'dtL1~i- chc111, .4 I' 7 0 2 J23, IIIC~ILI I~ I c I I I ~ I I ~~~ I~ , I I ( 10115 I<c\e:rr~,l~ In5t1!utc lor ~ h c Sc rn~ -A r~d I roplc\

Snndtsrr, T.11.. Scllubcrt. A.M.. ; ~ n d I'attcc~. 1I .L. 14x2 Matc~r~tk ~ ~ ~ e t l ~ o d o l ~ r g ~ and [ i t ~~ t l i i i r \ c \ t 11liy\111log> I"rgc\ 024-054 111 I't';~nrll \clc'ncc ~ 1 1 d l r c l ~ l ~ o l ~ ~ g \ (I'dttec. ti I and Lt!utig. ( I . cd5.j. Y(I.I~UIII. ICX.IS. I S \ AIIIC~IC;II~ Peanut K ~ \ ~ a ~ e l i i i r r ~ i tduc3t101i SI~CICI~

Sengupta, I1.K.. Sironi. G.S.. Pokhriyal, T.( .,,inti Ka in~. X1.S. I977 I ' ~ I I I ~ ~ ~ ~ ~ ~ S I ~ ! ~ ~ I C c(1111roI (11 I l ~ ~ r r ~ r ~ g 111 g ~ o u ~ ~ d - nu1 (.\i~i./ri, h~pog:r<.:r I ) C'lirrcrit Scrcncc 4 1 271 ,272

Simrnonds, 1,.P.. rr~id Ong, ( ' . K . ( I n p r w ) I<c.\por~rr 10

U ~ L I I ;IIII!II ( l e l ~ c ~ t III 4 \t;in(I 01 g r o ~ ~ n ( l ~ r t l., lr<r~ h ~ \ I I~~O~~IL*~~ I ) I . h i i l c r rlre Asiridlh o l n o t ; ~ n ~ .

Smith, I).II. lYXh I)i.\c;~rr-li!icc.i\t~rig nrrt hod lor ground- nut Icaf <[>or d~ \ r : ~ \ c \ P a p 2IO-242 in !\g~oniclccirt!lop\

groundnr~t p r o c r r d ~ n g ~ of an Inlcr~rat~oni i l 5\rnpos111111,

iC AUK 19x5. IC'RISA'T 5atielritr1 ('enter. Krarnc>. I1nt;~nchetu. 32.P 502 324. Intlla I~~tc rn ; t t ion i~ l

Crop) Krsearch In\trtutc lor Ihc Setil l-Ar~tl 1 ~uprc \

Squire, (;.It., Marshull, B., 'l'rrry, A,('., atld Montcith, J.L. 19K4. Kcjponst. 10 tcnipelaturc in a \t,rnd of pc,~rl rr~illet \ I 1.1ght Intelceptroti and (Irk ~nattcr producl~ol l Jnurrial (11 I xperlrnerrtal Htrtnriy lS.SL)L)-610,

Stansell, J . H . , drld IBulla<,J.t. .lr. 1979. t'c;irrut rcspl!rlsc 111

t ~ r n i r ~ g and ~ U I ;ltlon { i fdroupt~t stre\\ a\ ~el l rctc<l III Lcl ncl

Virmnni, S.hl.. .rnd Singh, P. IOxh ~ ~ ~ I ~ ~ ~ I I I ~ I ~ I ~ I I I O ~ I ~ ~ , I I I~I,II,IC~CI I\IIL\ 01 t he ~ I L ! I I I ~ ~ ~ ~ I I I I - ~ I ~ N I ~ ~ ItTgilin\ 111 !lit' \~IIII-~III(~ tropic\ I1;igcs I 5 1 5 III , \ g ~ ~ ~ ~ r ~ c t c i ~ r o l c ~ g \ ill

Q ~ ~ I L I I I ~ I ~ ~ I I I ) ~ ~ C C C ~ I I I ~ \ 01 ;In III~~III~IIIIII,~~ S\rnpo\lt ir i~. !I-20 AIIR IOX5, I I ' K I S A I \,~Iii~li:rn (crltC,r. VI,III~C\. h ~ g c ~ I ' ;~ l ,~nc l~er i~ . ,\ 1' 5(1! 124. l n d ~ ; ~ 1111crn,tt1~11i,1l Clop\ Kc\c;rr[ h II~\~IIIIIC for 111r \ ~ I I I I - , \ I I ~ I 101ir{.\

iicld arid qi~i~lr ty. I'roct.ed~ng\ ol .Arncrlcan I'ciln~lt K c \ c < i r ~ t ~ nd tducat~ciri Suclcty I l .h l