Combining ability studies for heat tolerance traits in bread wheat [Triticum aestivum (L.) em. Thell].

A set of 28 hybrids were developed involving eight diverse parents (HD 2687, DBW 17, PBW 373 ,Raj 3765, Raj 3077, Raj 4037, Raj 4083and RKA 501) by using diallel mating system without reciprocals. The 28 F1's and 8 parents were grown in Randomized Block Design with two replications during rabi 2008-09. Analysis of variance revealed that variance due to genotypes, parents, parents vs. crosses and crosses were highly significant and significant for all the traits studied. Significant mean squares due to general combining ability and specific combining ability in pooled analysis revealed significance of both additive and dominance gene effects in inheritance of all the heat tolerance traits in wheat. The low predictability ratio revealed that all the characters studied were predominantly controlled by non- additive genes action. The present study has identified desirable parents RKA 501, PBW 373, Raj 3077, Raj 3765 and HD 2687 for most of the heat tolerant parameters. The importance of additive but mainly non-additive gene action is highlighted. Improvement in heat injury and other heat tolerant parameters should be possible by resorting to biparental mating followed by recurrent selection or by diallel selective mating. [ABSTRACT FROM AUTHOR]