Genetic Associations and Path Coefficient Analysis of Sesame (Sesamum indicum L.) Yield and Its Components

Abstract

Fifty-four sesame genotypes, comprising 51 genebank accessions and three farmer-preferred cultivars, were evaluated during the 2023 and 2024 summer seasons at the Kassala and Gash Research Station, Sudan, under surface irrigation using an augmented randomised complete block design. The study assessed phenotypic and genotypic correlations among nine agronomic, phenological, and yield-related traits and identified potential criteria for indirect selection. The traits evaluated were capsule length, number of capsules per plant, number of branches per plant, plant height, height to first capsule, days to 50% flowering, thousand-seed weight, days to maturity, and seed yield. Combined-season analysis revealed that number of capsules per plant had the strongest positive phenotypic (r= 0.745) and genotypic (r= 0.791) correlations with seed yield, followed by number of branches per plant (r= 0.632 and 0.696, respectively) and plant height (r= 0.433 and 0.421, respectively). Capsule length, days to 50% flowering, thousand-seed weight, and days to maturity showed positive associations with seed yield, whereas height to first capsule showed a weak negative association. Path coefficient analysis identified number of capsules per plant as the most important contributor to seed yield, with the largest positive direct effect (0.40) and a substantial total indirect effect (0.34). Number of branches per plant (0.22) and plant height (0.20) also exhibited positive direct effects, whereas height to first capsule and days to maturity showed negative direct effects. These findings indicate that number of capsules per plant and number of branches per plant are important yield-associated traits and promising indirect selection criteria for sesame improvement under Sudanese irrigated conditions. Further multi-environment testing is recommended to validate the stability of these relationships across major sesame-producing environments in Sudan.