COMBINING ABILITY, HETEROSIS AND GENE ACTION FOR SESAME YIELD AND ITS COMPONENTS

The current work was done during the two successive summer seasons of 2022 and 2023 at El-Giza Agricultural Research Station, Agricultural Research Center, Giza Governorate, Egypt, to study the inheritance of yield and its components in sesame. Six parents were crossed in a half diallel mating design to produce 15 crosses. The analysis of variance showed highly significant mean squares for all the studied traits, indicating wide diversity among the parents in this study. The highest results were obtained for the traits of seed yield per plant (g), 1000 seeds weight (g) and oil percentage from P1 and P5, respectively. The cross (P2×P5) gave the highest value for seed yield per plant (g), 1000 seeds weight (g) and oil percentage. Mean squares due to both GCA and SCA combining abilities for crosses were highly significant for all studied traits. The GCA/SCA ratio large exceed the unity for all studied traits, suggesting that the largest part of total genetic variability associated with those measurements which were result of additive gene action. The P5 is good combiner for several traits. The crosses (P2XP5) and (P5XP6) gave SCA significant and positive effects for seed yield/plant (g) and oil percentage. The maximum and highly significant heterosis estimates for mid and better parents, for 1000 seed weight (g), seed yield/plant (g) and seed oil percentage were obtained by cross (P2XP5). Additive (D) was highly significant for Fruiting zone length (cm), number of branches/plant and capsules length (cm), indicating that the additive gene action was important in controlling the inheritance of these traits. Similarly dominance, (H1 and H2) components values were significantly positive for all studied traits. (H1) was greater than (H2) in all studied traits. All estimates of the environmental variance (E) were insignificant for all studied traits. The over- all dominant effect (h2) was positive and significant for all traits except fruiting zone length (cm). (H1/D)½ values were more than unity for all traits. The proportion (H2/4H1) was lower than 0.25. The ratio of KD/KR was greater than unity for all traits except number of capsules/plant, 1000 seed weight and seed yield/plant. Narrow-sense heritability (h n.s) estimates was low for all traits.