Combining Ability and Type of Gene Action for Earliness, Growth traits and Biological Yield of Diallel Crosses of Sesame under Water Stress Conditions

Six sesame genotypes representing different traits were crossed in a half-diallel in the summer season of 2021. These experiments were carried out at the Experimental Farm of Agronomy Department, Faculty of Agriculture, Mansoura University, Dakahlia Governorate, Egypt during two summer seasons of 2021 and 2022. The results indicated that mean squares of both GCA and SCA were high significantly for the studied traits under investigation at both conditions, indicating the importance of additive and non-additive effect in determining the performance of these traits. GCA / SCA was less than unity for all studied traits under both conditions referring that the non – additive (dominance effect ) variance was more important and played the major role in the inheritance of these traits and therefore the selection procedure for these traits was more effective in the late segregating generations. Based on general combining ability estimates, it could be concluded that the best general combiners were; P3 (8-94-115 Hybrid) under normal condition and P2 (3-110-304 Imported) under both conditions for days to 1st flower. For days to maturity were; P2 (3-110-304 Imported) and P1 (1-48-74 Hybrid) at normal condition and P4 (11-35-545 Imported) and P5 (13-93-585 Imported) at water stress condition. While, the parents P2 (3-110-304 Imported) and P6 (Giza 32) for height to 1st capsule under both conditions. P2 (3-110-304 Imported) under drought condition, P3 (8-94-115 Hybrid) and P6 (Giza 32) under normal irrigation were for plant height.