DETERMINING THE GENE ACTION AND COMBINING ABILITY OF F2 BREAD WHEAT BY DIALLEL ANALYSIS

For ensuring the food security under changing climate and decreasing agricultural land area, genetic improvement of yield-related traits is the prerequisite for developing newer, better-performing varieties of bread wheat. Therefore, a study was conducted at the Sakha Agricultural Research Station Farm, Egypt, for investigating the ability and nature of gene action with the mode of inheritance for the grain yield and its component traits in F2 bread wheat for identifying the superior genotypes for three consecutive seasons. An experiment was conducted to test ten parent genotypes of bread wheat along with their half-diallel hybrids (45 F2 segregating populations) using the randomized complete block design (RCBD) with four replications. The results revealed that general combining ability (GCA) as well as specific combining ability (SCA) had significant differences for most of the traits under study. In addition, Baker's ratio confirmed the superior role of additive gene effect in controlling yield traits of wheat. Moreover, the GT-biplot data analysis and GCA effects (& gcirc;) illustrated that the Vorobey (P3), Giza 171 (P10), Line1 (P1), and Line 7 (P9) had the highest values for the yield traits. Likewise, F2 hybrids [Line 1 (P1) x Line 5 (P6), Line 2 (P2) x Vorobey (P3), and Line 1 (P1) x Gemmeiza 11 (P7)] remained superior for the yield contributing traits. Furthermore, the estimation of GCA incorporating the additive component (D) underscored the significance of additive gene effects more than the SCA incorporating dominance (H1) for the traits under investigation. Lastly, the graphical analysis of Wr/Vr with (H1/D)0.05 pointed that the plant height, kernels number per spike and 100-kernel weight along with grain yield in F2 tend to be determined by additive gene effect through partial dominance.