ELS EVIEKResponse of short-duration pigeonpea to litrogetlapplication at'tc.1short-term waterlogging on :I VertisolRyoiclli Matsunaga:k,Osamu It(.),Satoshi Tohita' , 'l'hccrthnmP. Rno, C11t.i J o h : n s c il i f c m u iCro/?,v / uL/ J , 11( / ,irit df *jitr 'I I/! , .SCIIII.,\ I,/7'ro/ tc (/C,4/S,\T'i, /',I III 110r1t.4Acccl) cJI0 Jul)1'502 , ?,/, /t:,i , iL)ll,IShort-duratioi pigeonpea sul'l'ers t'ron watcrlogging di m; jicfolloui ig11c,1vyrai t'nllat l l cpre-llowu ngs : g1111c M I I I \\1t11high clay content, such as Vc .tisols.Effecth of short- crm\v:rtcrlol:g g( 3 d ) on hhoo and root gi.owth 0 1 ' s l o r t - d r : t o rpipeonl cagrown on a Vertisol licld were quu rtiticd.;111dtho lior 0 1 ' uiitcrlcigging t l . n ; hyg cI - ( C01 C11itrtigc11,III[:t'e ti! zcrwas examiacd.I educcd lcaf chlorophyll, increased scncsccncc ;lnd obscissio of I C I W I Ic; vcsw c ccihhcrved \ iil1111 3 L I (11' I I Si i t i i r i (11oriwaterlogging. Koot growth and synlhiolic N2 fixation were also hcvcrcly i nl ; rcd.Koot J1s1r1huuoii301 \r ; rrloggcdI I L I I Iu ereshallower than those of the control during the s lbscqi rntrccovcry period hccau.\c new irdvc ltitioi s1 0 0 1 \ wurc for111 Ji l l IIICs h a l l o rather than deep soil lnycr. Yicld o f wntcrlopgcd crops W;IS hignifrci l tly r i a l l 111;111c r 1111: C \ I I I ( I .Top-dressing of nilrogcn at one da yaftcr Ihc tcrri inatio of watcrloggi g: lI '\ iatcJU ' : I I C d1111i;ig O I cithcrI I i)rllplcti.lyor p. itially. Lc;if chlorophyll and shoot dry mass nf watcrloggctl pln itswcrc 7s 2 n d 8 4 ' k trt rllc v; luc.;I I I contrcil pl:1111\irnmciliatcly aftcr watcrloggi lgbut rccovcred lo 91 a11tl9X%of the control c: lucsat thc pod-filling srazc w t ha top-drc\sil pol'50 kg N h a w LNitrogen.applic:ition promoted root growth in rhc slii llnwso11I: ycrsclurinp llrc lirst I I I ; ftcr: ppl c:ittor ,ilnclin tlic deeper soil layers during thc subsequent 16 d. 'Tutal notlulc oclivity was signilicantly rctluccd hy 100 Lg N II;I '. h111iricrc; sedby 50 kg N h a - ' around onc month iifter thc top-drcssil g.'l'hc I-c(luctiunill scctl yicld u.; r,lurpcly co npcriadlctlI'orby 50 hg N ha' I, because of recokc yfro111 watcrlogging darnnpc to al or lir idroot growl11 tnvolv ngincrca\cd trdule.rcIlvtiy.1. I n t r o d u c t i o nShort-duration pigeonpca (4-5 mollths to maturity)is being increasingly used in India, becausc o f the highpotential for developing n e w a n d productive croppingsystems, c o n p a r e dwith traditional cropping systems* Corresponding author. Present address: Japan Intcm; tionalResearch Center for Agricultural Scicnccs (JIRCAS). Ohwahhi I2. Tsukuba, Ibaraki 305. Japan.I Okinawa Branch, Japan lnlernaiiunal Rescarch Centcr for Agricullural Sciences (JIRCAS), Ishigaki. Okinawa 907. Japan.0378-4290/94/ 07.00 Q I994 Elsevicr Science B.V. All rights rescrvedSSDlO578-4290(94)00062-Xusing 111cdiun1- (5-6 r n o i i l o r )lung-duration ( 0 - 9monthh) pigeonpen ( P a n w a r and Yadav, 198 1; Kurl iirR;io a n d Dart, 1987). Shun-duralion pipcoripca is lessuft'ectcd I y tcrrninal drought stress, whicli is oric of thcimportiint factors that limit seed yield in lony-duruliontypes (Johansen ct al. 1989). Paradoxiciilly, sllortd u r a l i o t pigeonpen sulfcrs f r o nwaterlogging d a n n g cfollowir gheavy rainfall on clay soils such as Vertisols( R e d d y and Virmnni, 198 1 ) . ' h a u h a (i 1987)reportcd that pigeonpea w a s very susceptible. to watsr-

logging and that nearly 50% of waterlogged plants wcrckilled by a 4-d treatment.In most leguminous crops leaf chloroais and senescence prevail after the initiation of wotcrlogging, atiddamagc seenis to bc n o r e sevcrc than in cereal crops(Canncll et al., 1979). Root growth is also i npairedby w itcrlogging (Cannqll et al., 1979; Heathcrly iuitlPringle, 1991; Pardales et al., 1991; Thomson ct ;I/.,1992). In cereal crops waterlogging restricts scoiinalroot growth, causes a breakdown of root tissues i ntireduces root mass. In contrast, it promotcs the fortnatlon of nodal roots from the shoot basc in wlicat(Trought and Drew, 1980), oats (Caancll ct ill., l985),sorghum (Pardalcs ct al., 1991 ) and barley (Cat ncllet al., 1984). Few studies havc reported tlic cl'l'cct o fwaterlogging on the root distribution in ficld-grownIcgu ninouscrops (Cannell ct al., 1985). Sincc pigconpea is well adilpted to tlic semi-arid tropics, severalphysiological studies have been cat iedout on droughtresistance (Muchow, 1984; Flowcr and LudIow, 1987;Lopez ct al., 1988; Johansen ct al., 1989). Ilowevcr,therc liavc been relatively few studies on the rcsponscof pigconpea to waterlogging (Chiiuhi n,1987; Matsuuaga et al., 1992).Depression of nitrogen uptake after watcrloggiligli111itsthe growth and grain yicld of cereal crops (Watson ct nl., 1976; Cannell et al., 1985; Veen, 1988),soybean (Nathi nsonct al., 1984; Sugitnuto et at.,1988b) ilnd pigeonpen (Matsunaga et al., 1992).Therefore, nitrogen application can compensate partially or completely for the reduction uf grain yield tlucto waterlogging damage by pro noti igtillcring in cisreals or increasing the rate of photosyrithcsis in soybeanor both (Watsonet al., 1976; Cnnnell ct al., 1985; Vccn,1988; Sugimoto et al., 1989). There has, Iiowevcr, hcenno report on the influence of nitrogen npplicatio towate loggcdpigeonpea.In India nearly 6 Mha, especially of Indo- ;angelicalluvium and Vertisols, are prone to waterlogging during the rainy season (Chauhan, 1987): According tothe n eteorological study of Red ly and Virmani(1981), waterlogging is a major constraint to rainyseason crops on soils with high water-holding capacity.Sinha (1981) postulated that low yield of pigconpeain some areas may be due to waterlogging. In the present study, we attempted to quantify the effects of shortterm waterlogging ( 3 d ) and top-dressing with nitrogenfertilizer on shoot and root growth. We also invosti-gated il' liitrogcn application riiight alleviate yicldreduction duc to waterlogging, because brceding ofnew val.ieties toleratil to wale1 logging i.s not completcd.2. Material and methodsS h o 1-duration pigconpca (C ljotrnscujutr (I,. )Millsp, ghcv. ICPI. 87) was sown on a Vcrtisol ;I[ICKISAT Center on 17 Junc 1991 and 18 Junc I992Thc so11 t r l ' i (0-30c c c n )was a ci\lcareou heavyclay, a colilnion property of Vcrtisols (Keddy and Virmalii, I OS I ) . T c idnys before sowing, singlc super IiospIiakand urca wcrc.broadcaht at 60 kg P and 75kg N l i i ', slid incorposntcd into tile soil to 20 cmclcpll hy disc ploughing. Scetls wcrc sown 15 cni apiuti l l two rows on tither sidc of ridges spnccd at 60 cni( i.c. two rows on a ridge, and tl cn15 X 30 cm spacing).At 14 11 i fters o w i pli ntsgwcre thiuned to one pli ntpcr hill.l'rc; tliicntswerc allo iitcdin tlic field as n split-plotdesign will1 three rt'l,litates. Main plots ( 9 X 30 IT] inI99 I end 0 X 20 In in 1992) wcrc control (no watcrlogging) and watcrlogj;ing trcatrncl,ls, atid subplots( 9 X I0 n wcre) N treutr11cnts. Before tlic waterloggi lgtrcatnictll, subplots were cncloscd by eaitlicn bunds turctnin water on the soil surl'ace, W;dzrlogging wasimposed ;it the prc-!lowering stage in u uofs bothtycars wlie ilcgurninous crops are v e ysusceptible towatcrlogg ng (Mincliin ct al., 1978; Cannell cl al.,1979; Sugimoto et al., 1988a). The treatment wasal plietlby furrow irrig; tionon thc morning of 17,Augusl 199 l , and 20 August 1992. Water was applieduntil it rci chedaround 5 cnl above tlic tops of ridges.This lcvel was tnai itair cdby adding water as neccssary, ulltil noonof 15 August 1991 and23 August 1902,respcc ivcly.One day after thc termination of wateslogging ( DAW) , urca was top-dresscd at 4 5 0 and i 00kg N ha (referred to as NO, NI and N2) to e;rchsubplot in 1991, and at 0 and 50 kg N lia-' (NO andN l ) in 1902.Oxygcr concentralion in the soil air at 20 cm depthwas monilored every day during 1 to 29 August 1991and on cvcry second day l'rom 10 August to 10 September 1992 with an oxygen analyzer (LC700F type.Toray 1311gineenLimited, Japan) as an index of soilaeration. Around 5 ml of soil air was collected with aplastic syringe at 20 crn depth through glass tubes'

(inner volume 0.I ml) that had becn instiillell in blithcontrol iund watcrloggcd subplo: with N1 one weekbefvrc ineasurements began. Thc oxygenconccntralio iw: src,.ardrd ash% whet) soil air c o l t l hei os: niplcdttlu .inpwi tcrlog eingand, in 1992, I'raluent rainfall.l c i d c ofl c I)i yro/ ittltnrtrcblight wi s lcpligiblcinmaG,:plots it1 1991, but it severcly dan ngcdplants i nso111cparts ot'scvcral subplots in 1993. dur to frcclucntprccipit; tionin early August. Thcrcforc, in 1993, S;IIIIpiing ul' plants was tlladc ' Y O I I Iiireas not al'fccted hyI ' l r o l ablight, i o rtor avoid thc dircc pathologicalcl't'ec JII the physiological and 11lorp11ologic;iIrrsponxcof pigc'onpcia to waterlogging.SII IOS ; II I I I CwcrcSti kc lfro111I\VO I .2-111row\ ;it10- I;) 14-d intervals i ftcrwatcrloging, a1it1 liciroven Ir ctlIII:IYS dclcrniinctl, I.eaf' discs (?, nlm tli:unic cr)I L C L ,j i111chcCIwith ;I cork horcr I'roni thc l'ou tilc;ilt)clo\v tllc uppcr nostunfoldcd 1c;ii'on thc riisii h l i i .T l cto::il chlorophyll conccntr;ttion was Jc crminetlhyspcctrr pliotc nic ricmcasurcmcnl following clilraclionwiti Xi)%, acetone (MacKi lncy.1911 ).'I h c csoil colu11ii1 were tiikc11, rcspcctivcly. vcrtically helow ;I plant, and at 10 :ind 20 c i i11w;1y i'ronipl,i!i:s in thc intcrrow of ull h p l i )SaniplinpI .wnsc;ar.r icil out lo 100 cln deplll will1 ;I 5.08-c1u tlia nctc*r:iugcr on 41 DAW in 1991 and I, I2 a id2S DAW 1111992. 'l'he soil colunltis wcrc sectioned into I 0-cnl layers :inti ciirefully washed with wuter to cxtrnct the roots.Roo1 lcngth was measured will1 n root length SciItIIicS(Com;\ir*,Coinmonwealth Aircraft Corporation L I I itcti, Australia) after roots wcrc scpasatcd I'rum o t l c '1 I i 1 1 i tclcbris.So11 iionolithhwcre 1;ikcn to dctcrniinc nodulc aclivily hy acctylene reduction assay on I? I AW in 1991,i ndiai 1, 12 and 38 DAW in 1992. Soil nionoliths of'30 r.30 X 30 cm were carefully taken to spiol lniddlcridge lo midclle row in all subplo s.Roots and nodules\vcrc irumediatcly washed from thc soil and placed inloincubation bottlcs. Aftcr thc addition of acctylcnc( 10% o / u ) into bottles they were incubatcd at 30 C I'orone llour to determine ethylene evolution with a gaschromatograph with a FID detector (F33 type, PcrkinI3tncr Limited. UK) .Seed yicld was determined by harvesting malurcpods from around 10 m2in i l l plots twice on 30 Octoberand 2 December 1991, and fro1115 to 8 ni2 on 4 Novctnber and 3 December 1992.3. Krsults.j,1, ) , . v l l ,L.,.il,,.(,,;l,,l,,:,jl,/,.0\\gc11L . I I C I II I I soil , I, irI :\I 20I I CIII iicptli \I ,! 1901 :\;id L * I I I ; I ;I I I IC I O IcSoll\talil,I[, I.\)LIIIII20' t i l l hotli L.OI II.OI;itld \v;itcrIt)gp8dpi015 IlCIolc \\ ,itcllo . lll !(l:l;.I . \ ) , Xi) so11 'ill \ \ ; I \s;1111 1Ii cltl111,i11 tliib 1-d \ \ ' : \ I c i l o iI C ; I s I I \ C01)I .s c i O I I I I I ; I :\ \I;OI \ I sig i lic ii \:ljION cr I I I \\ ;IIL*Il o g g I I Il, I I ill ct) itt. )I I o I !'or I .\\\'. 'l'licri ;il' ,l)sygc iL \ I I C I I I ; I rcco\c ctiI III(lt1i 4,Ij10 20''; , I I L to tii11ii111:iIr;ii il'; lld11ri11 1111spcriotl.I CC;I\I C01' C C L IS;IIIII',I!ICI Il i ' l :111(li . I I ' I C [lieI I I I I olI IOY);CIII i i , i s u r c ill: 1002c \ [:is. 111 ) *IIO g;!s i*o111tIl)c J I I I I C L I Irol) !lie \ t i ii l l i * i t l i c o i t t i lor \\ ;ll l lo ! cii[ I O l h (01 1I1c tirs: ,-i;.I11d;l! \ ( I0 10 I?, \ L I I I l:ig, I I H ) , cvc i1li0 1gl111,) I I L *wiitcr x l t111 lilll) cs csllllcllt ll[ l\)I. 'l'I1e c llcclllr iti\ l I l l collll llpIi11s r *co\'crcc!lo /(I( i ill 111 'ili!ti;ltit)ll i ' \ \ i t l ! o ; : g i l l :itid sI; yctl; ro rricI20iA IIICI, - II'I I.,c i , c p;I[t 1 1 1 I C:III I I I1C1 1 1. L \ )I L I IIOth( bl' C S ' I C I ' L Illlllg C ) L !(;;ISli)r 4 clays (watciloyg ngpcr ijtl I - I i1;1),: l'tcrtllctscatllicllt I . O.\!I L IIcol:ccntriltloli 111 \\'iIlcIloppt'tl p l l \s C L O \ lllolch L I \ I O \ V I Ill loo,? , 01 1 ii!t!(l\vllll 1001,1101 i i l ' l ' tl ycriiinf; lllIIIm*3020AuguslSeptemberbig. 1 . I ,t11) relnlull (c, lulllllr)und cahon;il ch,lllgc 111 oxygullc o ! c c i rIIIs oil l airo a: 20 cnl d c p hill 199i ( A I I I I902I (BIOhygc ici ncc :r.aiio )ill cotitrol (yolid IIIIC) and wi rcrlogging(1110ken linc ) plorc; duration of watcrlogg ngIrriltmcnl ( A ) 12- 1 .'. \ U L I \ I 1901 and (B)20-13 Augusr 1902.

"Irwith N top-drcssing. This effect disnppearcd, howcvcr,by 30 DAW (Fig. 21)).Sttoot growth beciin ei11ucI.r slower after wa!crlogging without N top-drcssitig in both 1091 and 1997,(Fig. 3). Shoot miiss of watcrloggcd plants wasincreased with N1 trcahnent at 30 n r t l40 LIAW (12ig.3B). Howcvsr, N2 treat ncntdid not inctcasc sl ootmass of w;;ints. Thc ci'fect ot' N top-drcssing was no1 significant for control plil rsduring [liesampling pcriod ( L to 40 LIALf'; Fig. 3 A ) . Stlootgrowth of wiiterloygcd pla itswns cnh;incc(l by N topdressing after 30 DAW in 1992 (Fig. 3U). 'rllerc wasco siclerilblcit crcascill shoot inass of co1lt1.01l.ilants i t20 DAW but tlic dif'r rcncewas losr by 30 DAW(Fig. 3C)., 4'?(// ,i- 20II,1in nlrlst C I Y C Stoot,I :ig,[hdc :sity (RI,D) clcclitlcdlinenrlywit11soildcpthtt) 10 cm dcpth ;n 41 DAWDays aHer termination of waterlogging(inirl-pod-lillingstage)in1991 (Fig. 3 ) . In NO, shortFig. 2. fiffccl of N top-dressing on ctilo .opliyllc o i c c t .iil l t i o imaturc uppcrlenvcs nrtcr walcrlogping ill I99 I ( A : ctt ltrol.13: w:llcr.tcrin waterlogging incicasctl IILD in the 0.1C cm soillogging) and 1992 (C: cnnlrol, I):wntcrlogpinp).NO (C)), N I ( I )Inycr (3.17 i:0.99 versus 2.46 :t 0.37 km I I - 'for ;liemd N2 ( ) trci trncnts.Vertical burs itrc sta tli rclc r r o r h DI' IIIL';IIISfor the co npnrisossi l any trcutlllclit co tihir atiot .to20-%100103040atid reached almost h s:uncclcvcl as in control plotsby 10 DAW.3.2. Lct chlnro )hpllor clshoot gro\\ /lrChlorophyll conccnvution in Inaturc. upper lcavcs ol'control plallts incrcascd rapidly from I (i round14 dbefore flowering) to 30 DAW (ci rlypoll-filling stitge),but decreased at the 1;ist measurcmcnl ( 42 DAW) in1991 (Fig. 2A). The scusonal it:crcasc wab nuchslower fur watcrloggcd plants witllout N top-dressing(Fig. 2B). Tllc chlorc phyllcoilcentratioa of both cantrol and waterlogged })li tItswah significantly enhancedby N top-dressing (NI and N2 trent nents)at 14 IIAW.This was particularly distinct for waterlogged plantswhich showed no differcticc in leaf color from controlsat this stage. However, he effect of N top-dressing onleaf chlorophyll disappeared by 30 DAW for cont oland 40 DAW for waterlogged plants. Ixaf chloropliyllconcentration in control plants was not affccted by Ntop-dressing in 1992 (Fig. 2C), while concentration inwaterlogged plants increased significantly at 10 DAWF1g. 3. Bfkct ol'N top-drrssing on shoot muss nftcr wi terloggingin1991 (A: corltrol, R: ualcrlogging) nnd 1992 (C: conlrol, D:water.logging). NO (3).N i (R)aid N2 ( t ) trcatliiellts. Ver icnlbusarc: standard errors of nleans for the conipnrisons :I( :111ytreatmentcombination.

So:l depth ( cm )l'ig, 4, Effcct of N top-drcs\i ::o n root lenplli lcnsityi l l v;isicrrr\ soilI; ycrsal 41 days nflcr ttr11iin;lrinn of watcrlogping i l l l ' l l / l . C I I I I I I . IA, U) i n dwaterlogged plnlith (C,D). NO (0).N I I N) ;IIKI N!I 4, j treatnients. Vertical birrs arc sl;lnd;lnl clrors or nlc:ini I'ol Ihcco nparisonsat any trci nic itcombinalioli.rxicankstandard crror oT watc .lopgcd ant1 control.respcctively), but decrc: sedconsiderably ill lht: soillayer 50-100 cm (0.30 5 00.03 versus O.bI rk 0. I J kill111'. f'ur wate logpcdnn lcontrol, rcspcctively ) . Consequently the root distribution of waterlogged pigconpca bccamc slinllow without N top-dressing.Top-dressing of N did not affect R1.D signilicantly inboth 0-50 cm and 50-100 c11i soil layers f ) colltroirplants (Fig. 4A and 4B).Meanwhile, the cll'ect of Ntop-dressing on RLD of wtrterloygcd pla itswas cvidcntin the 50-100 cm soil layer (Fig. 4D).The iticrcasc inKLD was more evident in N 1 than in N2, although bothwere considerably smaller than in the 0-I0 cm soillayer for control plants (Fig. 4C j.The observations of root proliles wtre carried outthree times in 1992 for each of the four treatments toexamine seasonal changes in more detail (Fig. 5).Increase in RLD of control plants without N top-di.cssing was confined mainly to the 0-30 cm soil layer from1 to 12 DAW and then extended to deeper layer (0-50cm) (Fig. 5A). Top-dressing of N enhanced rootgrowth of control plants in the &20 cm soil layer fromI*So11depth ( cm )I : I . 5 . SC SOIIIIcI1.111gciri r(1o1 lc iglhdcnsily in vnriouv a111l Inycrri11icrwi rcrloggingin 1392. Coa roliitNU ( A ) and N 1 (R ) r i i t i c n .;rnd walcrloggi gntNO (C)and NI (I)) Lrciilmcnls. I (0).I?. (N)tcrrn atiu rof wa eriogging.iuid 18 ( .t ) days

'Table 1Effects of N top-drcssiogo n torill nutlulcilflcr wolcrloggingilcliviiy I n111oI111 " 5-Trcntmcni199119926.585.791.355.804.421.761.09b. l R'r-.-.-.--*---ControlNON1N2Waterlogging NONIN2SE(k)hlhc tcrnliirnliorr --------0.840.61 : l c l i r g a i"SI;III I:WLI lg.iwors 01colnhil1:hiorl."Daysilflcrmc:lllsfur lhc colnl)arisorls at ilny trcarlllclllN Trcstmcnl Sccd yiclil ( g 111 ')'"Figt msill pnrcl hcscashow rcsi cc ivcsc .ilyiclrls :IS ;I I) of yield ut NO Lreallncnl in h chnillcwiitc ,logging),h c f cT;tblcrI.35% in 1991 u ;u 23% in 1992 ct)nlpalrd with thecontrol at the NO level (Ta5lc 2 ) . Ho\vcver. !lie yieldc.liffercnce het\veen control and wilterloggeil pla itsI)ccilmc n;ucl smalier \c.itil N top-di.casi lg due togicatcr N icsponsc of' w: tcrlnggctiplants. 'l'hc yield ,cductioiiin N l wu.; only 3% iii 1090 a11d 55;: it1 1991,;IS co npiircclwit11 llic ccn:rol.I I I : I I I C O I I I C( ICI I I I I . did decrcase in both co ltroland watcrloggcd plants,slightly with N l treatment, a ;dsignifican lywith K 2 .In 1992, seasonal climiges in 'L'NA were 111cnsurcdfrom1 DAW to 28 DAW. 'i'NA was kept llcii1 ly consfilnt illc o t r oplotsl without N-top dressing. W:rtci,loggingdepressed nodulc activity ltiucll niure sc\,crcly in 199:'.tllan in 1991. 'rNA of watc .loggcdplu l swithout Ntop-dressing was 33, 40 anti 52% of lht: conlrol at I,12 and 28 DAW, respcctivcly. The N 1 tsrat iicntslightlydccreascdTN, 12L)AW,butincrcascdTNAof both control and waterlogged pli nlsat 28 DAW.TNA of waterlogged plants with 50 kg N ha. ' rei\chcd95% of the control without N top-dressirlg ut 38 DAW,3.5. Seed yieldGrain yield was decreased considerably by waterlogging without N top-dressing. The reduction wasShort-d\ir: ionpigconpen was severely di nlagtdbyshort-[cr.iii w:itc lopgitig,resulting in ycllo\vi g01' thewllolc ci nop! I'ollowcd by sencscencu nncl uhscissionol'lowzr Ic, ves.'l'hc sy iipLc;n isi tribut:lhlc10 N sliort: I (Natl insonCel a!., 1084; Sugirlioto ct i i l . . I9SSb;Mntsu :agr! ct ul. 1902). Sligh iron chl )lusis ilig!itliavi: ;ilso occurred i;: tllc young upper 1e;lvclr aimulta cously.but C O L I Ir!ot Ocdi:;ti igi islledby visual observation. 11; contro! ; li)tsno .;)'ii )io liolaIrun chlo .osisoccuricd tluoughout thc growing i;c;rson. Nitrogcn toph r iinpaircd slioot gl'(') llhcotildressing co iipcns tccl icielg