Assessment of genetic factors influencing yield and quality characteristics in five diverse crosses of wheat (Triticum aestivum L.) through a six-parameter model

This study aimed to investigate the gene action governing the expression of various traits in bread wheat through generation mean analysis. For this purpose, six generations (P₁, P₂, F₁, F₂, BC₁, and BC₂) from five diverse crosses — Cross I (HD 2967 × PBW 343), Cross II (DBW 296 × DBW 327), Cross III (UP 2338 × NP 200), Cross IV (MACS 6478 × DBW 327), and Cross V (UP 2338 × UP 2847) were evaluated. The findings showed that the estimated mean effects (m) for all traits across all crosses were highly significant, indicating quantitative inheritance. Epistatic interactions were observed for all eight traits studied, and in general, the dominance effects (h) were greater than the additive effects (d), suggesting the importance of non-additive gene action. The presence of digenic interactions further supported the complex inheritance of these traits. Early generation selection may be advantageous. For grain yield and most other traits, dominance gene effects were more prominent than additive effects. Across all five crosses, traits exhibited large negative dominance × dominance interactions and high positive additive × additive interactions. Therefore, in wheat breeding, selection for improving grain yield and related traits should be deferred to later generations, as additive × dominance gene effects were less significant.