Gene Action and Association Studies of Yield and Its Components Related to Heat Tolerance in Bread Wheat (Triticum Aestjvum. L)

Abstract

I he pre<;ent inv~stigation wR\ undcnoken for the genetic onal)'sis of yield and th c<>mi">Jitnts relat~d to heat tul<mnce in bread 11heat usinp 10 di•c~e parents ••i:: UP 2425, UP 2565, K 9351, t.; 7'l03, K %4·1, PB\\ 590, WCW-'18-4, IIUW 468, Unnot halnu and IIUW 533, 45 f 1's am! f:'s developed b} adopung hJII dtullcl m:uing dc,lgn, nt Crop RMeurch Centre. SVI' tlnlwl"<ity of Agriculture ond fechnology, Meerut, during Huh/ •cason of 20 II 13 to n's<"•s the genetic informution lor yield nnd ~~~ component tmits ••r:; da) s to hcndin11- days to maturity, a;nun lilhng period, pl:mt height, number of producti\C! tillm per plan~ sptke length, number of •rokcl<o~ per spike, numb<:r of grams per 'Pike. 10<10-gntm llcosJ!t. flag l<afa~a, bit•logoal }ield per plant. gratn} ocld per plant, ban~t lnclc,, chlorophyll content at anthesls, chlorup/1)11 contentllt 10 da}s after unthni>, CTD 111 anthesis, CTD 111 10 d~ys atler IUithc•i•. dt)· gluten content, 11<h ct>nt~nt, hcJt 'us<epttbtlity indc\ and phenol colour reacuoo The mean data ol thc'c tmtts except phenol colour rc.t~hun \\ere subJc"cd to 'liltosttcal o1nd boomctr"al lln.tl)'"· to \<Or~ out the nnoly," ol vurlnnce, combining ubl l lt~ vnrinntc. oud their cllects, componenh 111 ~cncht v.oriances. munll'cstrotinn ol h~tcrosls, hent tolernncc, nnd coclliaicnt of vuriution (gcv and pcv), h<·rltubllity, ~cnctlc udvuncc, corrclullun ct~<:llicient and path coellkient unol) >is. Datil on rhcnul colour r.:nction wu• <>h>cf\cd 111 lhc categories i.e, daok brown, bro11n, light bro11n. 'light "'lour on the edge nnd no colour. All the (>31cnts and crosse• <<ere tlltcg<•riud •n these t:radcs. 1 he llllAI)sis of 'ariance rc<t'alcd sigrulicant ditlcrenccs (uodcr bte '"'"') the among tratnl<'nts, raren~ and h)bridi C\CCpt day. to hcadtng. da~s ou m3ttonl), gram tilhng pcrwd. numb<:r of prOOIKII\"C 111lcn per plant, gnun yield per plant. hnn.est indc\ urlll Cl [)at anthc>l~ on c.osc ol ~"'"'"t' Addtthe and non-lkldth\~ cell(' D<tion '"" lmp<•rt<lllt In controlling tho inhcnt.uKc ol nil the trans un,lcr •tUd) I he \ariance due h> gc• liM C<JU-ttcd to thJt P••rt ot 1cnrtic variance "hich " <luc II> udunt<c and ndJni•e ' addth\e etlc.:t.s. \\htlc \,ui.u><c Juc to~'"' "a.' n>~rtllcd '''non· nddni\C component'''' \':lft3ncc that mdudc d••rnntooK< and cpl\t•ti< •annnce On the ba'i' of o•emllgt:a cllcch. the parent' •·i:, Pll\\' 5'10, IIU\\' ~C>S. IIU\\' ~)3. llnn.tl h.1lna,!;: <16-1-1 und t t• 1~ !~ \\Cr"e the ~~t g(n~ml curnhuu:n, hlf m:t\tnnun nurnbc:r uf charJt.:((f'S u•H.ln rin~tl~ .und J.lle so'' n. MISl;C'tlnljth.tt thc!«' f!=RIS could bo U'cd Ill the btctdtng pl<l&rllllllllC t1> dt\d<lp tile j;t'O<It}pe> Sllll,1b)c f,,, tliC J>c-~t stress conditions and at t.he same time for an effective selection for many yield components in wheat breeding programme. Based on specific combining ability effects, five crosses viz; PBW 590 x WCW 98-4, UP 2565 x HUW 468, UP 2425 x UP 2565, UP 2425 x UP 2565 and K 9644 x Unnat haloa under late sown were found as good specific combiner for grain yield per plant. Therefore, it is suggested that wheat breeding for beat stress, gca should be considered as they may provide desirable transgressive segregation, if their cros£es have high sea with high mean value. With regard to dry gluten content, best five crosses viz; K 9351 x PB W 590, K 7903 x K 9644, PB w 590 x HUW 468, K 9351 x WCW -98-4 x HUW 533 and UP 2425 x HUW 533, and for ash conten~ the crosses i.e. UP 2425 x WCW-98-4, K 7903 x K 9644, UP 2565 x PBW 590, PBW 590 x HUW 468 and K 935l x Unnat halna exhibiting significant sea effects under E2 and were good specific combiners and these can be exploited for the improvement of good making chapatti quality. ~ The estimates of additive genetic variance (D) was noted as highly significant for the traits viz; i.e. plant height, spike length, number of productive tillers per plant, chlorophyll content at anthesis and CTD at anthesis • • under ~· Average degree of dominance ( H 1 I D )1n were found 10 be more than unity for aU the characters in E, and E. except grain tilling period in the £., indicating that these traits are governing by over dominance gene action. The genetic variance components analysis revealed that additive genetic variance (VA) and dominance variance (VD) played an important contribution for all the attributes. The additive genetic variance (VA) was observed for the traits viz; I 000-grain weight, number of grains per spike, flag leaf area, biological yield per plant, plant height, harvest index, chlorophyll content at anthesis in both the environment. The dominance variance (VD) was observed for all tbe traits viz; plant height, 1000-grain weight, biological yield per plant, number of grains per spike, harvest index, flag leaf area, number of spikelets per spike, chlorophyll content I 0 days after an thesis, days to heading, grain yield per plant, dry gluten content, chlorophyll content at anthesis and days to maturity under timely and under late sown. The phenomenon of heterosis and inbreeding depression assumes importance because of its direct use in wheat improvement through utiliuuion of hybrid vigour and selection for transgressive values of componems being governed by additive gene action indicated by less inbreeding depression. In respect of grain yield of per plant, best five crosses viz; K 9644 x Unnat halna, UP 2565 x HUW 468, K 7903 x PBW 590, K 9644 x HUW 533 and HUW 468 x HUW 533 showed significant and positive heterosis under E2• Therefore, these combinations could be utilized for selection either directly or by involving them in crossing programme for the improvement of grain yield and its component traits under heat stress condition. Inbreeding depression for grain yield per plant ranged from -46.02 (UP 2425 x PBW 590) tO 17.42 (HUW 468 x HUW 533). Four crosses i.e. HUW 468 x HU\V 533. UP 2425 x Unnat halna, UP 2565 x HUW 468 and K 9644 x HUW 533 showed positive and si&'llificant inbreeding depression in late sown. Three parents viz: UP 2425, K 7903 and HUW 468; and eight hybrids i.e. UP 2425 x UP 2565, UP 2425 x Unnat halna, UP 2565 x WCW-98-4, UP 2565 x HUW 533. K 9351 x Unnat halna, PBW 590 x HUW 468, WCW- 98-4 x HUW 533 and Unnat halna x HUW 533 exhibited < 0.5 (HSI}, indicating relative tolerance for biological yield per plant and also grain yield per plant under high temperature stress. Hence, these traits could be taken as selection criteria for breeding wheat genotypes su itable for heat stress conditions. High heritability coupled with high genetic advance was observed for the traits viz; plant height, 1000- grain weight, biological yield per plant, grains per spike, and chlorophyll content at anthesis under late sown, suggesting that these traits are governed by the additive gene action and would be more effective for direct selection towards better genotypes of wheat at phenotypic basis. Based on gcv, pcv, genetic advance and heritability, the characters viz; number of productive tillers per plant, harvest index, chlorophyll content at anthesis, ash content, grain filling period, dry gluten content under Ez. can be used as selection criteria for improving !he grain yield under !he stress environments. Grain yield per plant was positive and significantly associated wilh biological yield per plant, number of grains per spike, number of productive tillers per plant, days to maturity, 1 000-grain weight, harvest index and CTD at I 0 days after anthesis in both the environments at phenotypic level. Hence these traits should be considered during selection for high yielding genotypes. Path coefficient analysis, showed that harvest index had maximum positive direct effects on grain yield per plant followed by biological yield per plan~ 1000-grain weight, spike length, number of productive tillers per plant, number of grains per spike, flag leaf area, CTD at 10 days after antbesis, number of spikelets per spike, plant height and ash content under timely and late sown condition at both phenotypic and genotypic levels; whlle, days to maturity and dry gluten content only timely late sown condition. Thus, harvest index and biological yield per plant, may be used for simple selection to improve that grain yield. As per phenol colour reaction, three parents i.e. K 9644, WCW ·98·4 and HUW 533, and seventeen crosses viz; UP 2425 x K 9644, UP 2425 x WCW-98-4, UP 2425 x HUW 468, UP 2425 x HUW 533, UP 2565 x WCW-98, UP 2565 x HUW 468, K 9644 x Unnat halna, K 9644 x HUW 533, PBW 590 x WCW ·98-4, WCW -98-4 x HUW 468, HUW 468 x HUW 533, PB W 590 x HUW 533, K 9351 x K 9644, K 9351 x HUW 533, K 9644 x PBW 590, K 9644 x HUW 468 and Unnat halna x HUW 533 showed slight colour on the edge which may be used for !he improvement of chapatti quality. From the foregoing study, it is suggested !hat for exploitation of both additive and non additive components of genetic variation, material may be handled through pedigree method, reciprocal selection or biparamal mating for obtaining best transgressive segregants vis-a vis improvement in wheat. The promising general combiners can be exploited through convergent breeding method for incorporating multigenes into a common gene pool. Crosses with high sea values and per se perfonnance and high heterosis percentage may be exploited through heterosis breeding for the improvement of wheat under heat stress. Similarly, the crosses which involving high x high general combiners may also be ex-ploited in breeding programme for transgressive segregants in the early generation. Grain yield and its related traits like number of tillers per plant, plant height, flag leaf area, spike lenh'lh, spikelets per spike, and 1 000-grain weight play important role to improve yield potentia I and stability by evolve high yielding varieties which can produce economic yield and help the yield sustainability in those areas where heat stress is a major threat.