Association of quantitative traits and genetic diversity in Ethiopian sesame (Sesamum indicum L.) genotypes

Abstract

To enhance sesame yield, it is important to utilize diverse parents in breeding programs and implement an effective selection procedure, which exploits the association of quantitative traits. Therefore, the objective of this experiment was to explore the correlation among quantitative traits and assess genetic variability and diversity using both qualitative and quantitative traits. Correlation coefficients indicated a noteworthy (P < 0.001) positive phenotypic (rp) and genotypic (rg) correlation between seed yield and various traits: plant height (rp = 0.60; rg = 0.58), length of the capsule-bearing zone (rp = 0.77; rg = 0.80), number of capsules on the main stem (rp = 0.80; rg = 0.85), primary branches (rp = 0.66; rg = 0.66), and capsules per plant (rp = 0.90; rg = 0.91). In contrast, a negative correlation (P < 0.001) was observed between yield and bacterial blight disease severity, both phenotypically (rp = −0.60) and genotypically (rg = −0.76). The analysis of path coefficients indicated that the most substantial positive direct effect on yield (0.77) was attributed to capsules per plant, whereas other traits associated with yield exhibited a significant indirect influence on yield through capsules per plant. Qualitative traits exhibited diversity, except for plant growth type, plant growth habit, and stem branching. Shannon-Weaner (H) and Simpson (1-D) diversity indices were higher for interior corolla color (H = 1.63; 1-D = 0.66), seed color (H = 1.50; 1-D = 0.46), and capsule beak type (H = 1.08; 1-D = 0.50). The analysis of variance indicated a notable variation among the examined genotypes regarding quantitative traits, excluding internode length. The plant materials were divided into five clusters through cluster analysis, where clusters I to V consisted of 21, 29, 4, 4, and 6 genotypes, respectively. The current study has shown that the yield of sesame can be enhanced through indirect selection for traits associated with yield, particularly the highest number of capsules per plant. Furthermore, examinations of genetic diversity confirmed the presence of variability within the assessed genotypes, providing valuable insights for upcoming sesame breeding programs.