Comparison On The Effects Of Dwarfing Genesrht-Blb And Rht-8on Plant Height And Agronomic Traits In Common Wheat (Triticum Aestivum)

A study was carried out to estimate the inheritance, effect of dwarfing genes (Rht-B1band Rht-8) on desirable wheat characters and relationship between plant height and otheragronomic traits. Three tall elite cultivarsJinmai47, Xifeng20and Fenchan3were crossedwithRht-B1b and Rht8donor cultivars Zhoumai17and Jining13, respectively, to produce F1.The F1was allowed to self in order to obtain F2seeds. Then the F2segregation populationsand F2:F3lines were evaluated along with their parents.For the plant height, the progeny of Jinmai47and Zhoumai17showed the highestheritability percentage associated with high genetic advance (h2%88.49and GA21.92)followed by Fengchan3and Zhoumai17and Xifeng20and Zhoumai17(h2%85.36with GA20.11and (h2%84.80with GA23.40, respectively). Similarly, the progeny of Fengchan3andJining13demonstrated the highest heritability percentage (h2%74.32) associated with highgenetic advance (GA13.55) followed by the progeny of Xifeng20and Jining13and Jinmai47and Jining13(h2%69.49with GA14.56and h2%67.60with GA10.44, respectively).For the peduncle length the progeny of Jinmai47and Jining13expressed the highheritability percentage with high genetic advance (h2%73.42and GA4.66), followed by theprogeny Fengchan3and Jining13and Xifeng20and Jining13(h2%55.87with GA4.12andh2%34.91with GA3.07, respectively).Due toRht-B1b in the progeny of Jinmai47and Zhoumai17, the plant height and pedunclelength was reduced by40.18%and17.25%, respectively. For the progeny Xifeng20andZhoumai17, the effect of dwarfing geneRht-B1b was reduced on the traits plant height(53.80%) and peduncle length (18.96%). Whereas the traits plant height and peduncle lengthwas also reduced by38.21%and28.30%, respectively in cross combination of Fengchan3andZhoumai17.As far as the effect of dwarfing gene Rht-8is concerned, it was more prominent in theprogeny of Xifeng20and Jining13, which was reduced in plant height and peduncle length by30.26%and19.20%, respectively. Whereas, the progenies of Fengchan3and Jining13and Jinmai47and Jining13were reduced in plant height by27.14%,26.15%and in pedunclelength by14.86%,14.59%, respectively.Plant height was positively and significantly correlated with all the agronomic traitsexcept number of grain, in the cross Xifeng20and Jining13. These relationships were alsocorrelated positively and significantly with number of tillers and peduncle length in theprogenies of Jinmai47and Jining13and Fengchan3and Jining13. While the relationshipswere found to be not significant between plant height and rest of the traits in the both crosses,except peduncle length in Fengshan3and Jining13.The present findings suggest that the inheritance ofRht-B1b and Rht-8dwarfing gene ishigh although there is variation between different backgrounds of tall parents. It suggests thatthe selection at early segregation generation could be efficient for selecting superior lines ofwheat with the target dwarfing gene. For the dwarfing geneRht-B1b, the plant height wasreduced by43.56%in average, and by and by40.18%,53.80%and38.21%for the F2progenyof tall parents Jinmai47, Xifeng20and Fengchan3, respectively; As for dwarfing gene Rht-8,the plant height was reduced by27.92%in average, and by30.26%,27.14%and26.15%forthe F2progeny of tall parents Jinmai47, Xifeng20and Fengchan3, respectively; the effect ofRhtB1b was stronger than that of Rht8on reducing plant height. As for the effects of dwarfinggenes on number of tillers per plant and spike length, both the number of tillers per plant andspike length was reduced by32.74%and32.20%,24.11%and-4.94%for RhtB1b and Rht8,respectively. There were no stronger effects on the other traits of number of spikelets perspike, number of grains per spike for both dwarfing genes. The negative effects of RhtB1bwere bigger for all the traits that that of Rht8. Positive and significant correlations wereobserved between plant height and most of the other agronomic traits. These finding mayprovide some base for the proper use of those dwarfing genes in wheat improvement.However relationship of these traits might not be independent in their action and areinterlinked likely to bring simultaneous change for other characters.