Molecular and Genetic studies of Two Bread Wheat Crosses Using SSR Markers and a Six-Parameter Model Analysis

This study was conducted over three consecutive growing seasons (2020/2021, 2021/2022, and 2022/2023) at Sakha Agricultural Research Station, Kafrelsheikh governorate, Egypt, to determine the genetic factors controlling the inheritance of yield and its components for two bread wheat crosses: Shandaweel 1 × Yr 8 and Shandaweel 1 × Yr 15. Inheritance of yield and yield-contributing traits was investigated using generation mean analysis with data from six populations across parents, F1, F2, and backcross generations, using a six-parameter model. The data revealed significant additive gene effects for plant height and 1000-kernel weight in both crosses, suggesting pedigree selection could efficiently improve these traits. Dominance gene effects were less significant in the first cross; suggesting early selection should focus on these traits. In the second cross, dominance effects were highly significant for heading date, number of grains per spike, 1000-kernel weight, and grain yield. High positive heterosis was observed for plant height and grain yield in both crosses, with significant positive inbreeding depression values for all studied traits. Broad-sense heritability values were moderate to high for all traits, indicating the significant influence of both additive and non-additive effects. High broad-sense heritability suggests more effective selection in late segregating generations. High genetic advance was associated with high narrow-sense heritability for grain yield and number of spikes per plant in the second cross.