Heterosis and Combining Ability of F1 Bread Wheat Diallel Crosses

Heterosis and combining ability were estimated in bread wheat using 6x6 half diallel crossing at two seasons 2020/2021 and 2021/2022 at private farm at Bany Omran Village, Diermawas City, El Minia Governorate, Egypt. Results indicated that the mean squares of genotypes, crosses, parents, general and specific combining ability were significant (P < 0.05 or < 0.01) for most tested traits. The σ2g/σ2s ratio was less than unity, showing that non-additive gene action was more important for deciding performance of all traits. Cultivar parent, Sids 14 was an effective general combiner for biological yield/plant, grain yield/plant and number of grains/spike. Except for four crosses P1XP6, P2XP5, P2XP6 and P3XP6, all crosses gave positive significant (P < 0.01) heterosis for grain yield/plant. Heterosis of grain yield/plant over mid-parents and better parent ranged from 3.98% (P3xP6) to 33.14% (P4xP6) and 2.94% (P3xP5) to 26.97% (P4xP5), respectively. The four parents P4, P6, P3 and P1 gave significant and positive GCA effects for grain yield plant-1 and eight crosses had positive and highly significant SCA effects. P2xP3, P3xP4 and P4xP6 crosses exhibited highly desirable heterotic effects for most traits. Association among mean XP and GCA effects were positively substantial (P < 0.05 or 0.01) for days to heading, plant height, spike length, number of spikes/plant, biological yield/plant, grain yield/plant, weight of spike, weight of grains/spike and 1000 grain weight.