Heterosis and combining ability analysis of slow rusting stem rust resistance and yield and related traits in bread wheat

Abstract

Bread wheat genotypes with slow rusting stem rust resistance were crossed in a half-diallel mating design to identify superior parents for stem rust resistance combined with high grain yield (GY) and related traits. Significant mid-parent heterosis for area under disease progress (AUDPC) was observed in crosses 7041-1 × Danda’a and Danda’a × Kubsa. H04-2 × Danda’a showed significant mid-parent heterosis for GY, thousand kernel weight (TKW), number of tillers per plant (TPP) and reduced plant height (PLH), and significant better-parent heterosis for GY. Significant general combining ability (GCA) effects for all characters and specific combining ability (SCA) effects for most of the traits indicated the contribution of additive and non-additive genes in the expression of these traits, respectively. GCA and SCA ratios ( $$\sigma_{\text{gca}}^{ 2} /\sigma_{\text{sca}}^{2}$$ ) were less than unity for GY, TKW and PLH, suggesting preponderance of non-additive gene action at F1 for these traits. Additive gene action was predominant in the inheritance of AUDPC, kernels per spike, TPP and days to maturity. H04-2, Digelu and Danda’a showed strong GCA effects for most of the characters investigated. Crosses 231545-1 × H04-2, 7041-1 × H04-2, Digelu × Kubsa and Danda’a × Kubsa were good combinations for AUDPC. H04-2 × Danda’a, Digelu × Kubsa and Danda’a × Kubsa were good combinations for GY and TKW. Overall, H04-2 and Danda’a were good general combiners, and crosses involved these lines performed well for most of the traits. Hence, these lines may be used in breeding programs to develop stem rust resistant and high yielding cultivars.