ASSESSMENT OF SOME SESAME GENOTYPES AND THEIR CROSSES FOR PERFORMANCE, COMBINING ABILITY, AND HETEROSIS OF KEY AGRONOMIC TRAITS

Abstract

ABSTRACT: To identify superior sesame genotypes and hybrid combinations that can enhance key agronomic traits, especially seed yield, six genetically distinct parental lines, M₂A₂₄, B-₄₂, local-₁₃₁, H-₄₆, H-₁₀₂ F-_13, and H-₁₀₂ were crossed using a half diallel mating design at the Ismailia Agricultural Research Station in Egypt during the summer of 2023, producing 15 F1 hybrids. These parental lines and their hybrids were then evaluated in the field during the 2024 and 2025 summer seasons using a randomized complete block design with three replications. Analysis of variance for key agronomic traits in sesame across two seasons revealed highly significant differences among genotypes, parents, and hybrids, indicating substantial genetic variability and the presence of both additive and non-additive genetic effects. Days to 50% flowering ranged from 51.89 to 74.52 days, plant height from 83.21 to 179.20 cm, capsule length from 3.63 to 4.86 cm, number of branches per plant from 5.74 to 7.67, 1000-seed weight from 2.82 to 3.77 g, seed weight per plant from 28.01 to 37.48 g, and seed oil content from 52.69% to 59.21 % in the sesame hybrids. Hybrids such as P4 × P5 and P5 × P6 consistently outperformed parents in yield-related traits and oil content, demonstrating strong hybrid vigor. The Baker ratio for additive effects was moderate to high for most traits (0.78 for days to 50% flowering, 0.69 for plant height), supporting the predominance of additive gene action, though some traits showed greater non-additive influence. Significant general combining ability (GCA) and specific combining ability (SCA) effects were observed, guiding the selection of superior parents and cross combinations. Hybrids like P1 × P5, P2 × P3, and P3 × P6 combined early flowering, optimal plant height, and longer capsules, making them promising for yield improvement. Heterosis and potence ratio values confirmed strong dominance effects in key crosses, with P2 × P5 and P3 × P5 excelling in earliness and plant height, and P4 × P5 in number of branches, seed weight, and oil content. These results highlight the importance of selecting hybrids with high per se performance, strong combining ability, and significant heterosis for breeding programs aiming to enhance sesame yield and oil quality.