Genetic Variability, Variance Components, and Performance of Three Bread Wheat Crosses Under Aswan Conditions Using Six Genetically Diverse Parents.

A six-generation analysis of three wheat crosses derived from six genetically diverse parental lines revealed substantial genetic variability in phenological, morphological, and yield related traits. The F1 hybrids consistently outperformed their parents, indicating strong allelic complementation and the major of non-additive gene action. Significant improvements were observed in earliness, plant height, spike length, and yield-related traits in F1 demonstrating enhanced productivity potential. Scaling tests (A, B, and C) indicated that additive genetic models alone could not fully explain the observed variation. Dominance variance (H) exceeded additive variance (D) for many yield traits, and high (H/D) 0.5 ratios supported strong dominance or over-dominance. Low inbreeding depression in F2 generation suggested persistence of dominance effects. The close similarity between phenotypic (PCV) and genotypic (GCV) coefficients of variation confirmed that most variability was genetically controlled. High broad-sense and moderate narrow-sense heritability estimates were consistent with dominance-based inheritance. Performance evaluations identified cross III (Gemmeiza-12 × Intry-46) as superior in phenological traits, especially earliness in heading and spike length, whereas crosses I (Misr-3 × Sids-12) and II (Sakha-95 × Intry-30) excelled in yield traits, producing the highest spikes per plant, grain yield, and harvest index. Overall, the crossing scheme generated exploitable genetic variability, and the dominance-driven control of key yield traits emphasizes the value of late-generation selection or hybrid development under Aswan conditions.