Genetic Potential for Seed Cotton Yield and Fiber Quality Improvement through Heterosis and Combining Ability Analysis in Cotton (Gossypium hirsutum L.)

Background: Improvement of seed cotton yield and fiber quality in upland cotton ( Gossypium hirsutum L.) requires identification of genetically diverse parents and superior cross combinations. The present study was undertaken to assess genetic variability, combining ability, heterosis and trait associations using a line × tester mating design to facilitate effective breeding strategies for yield and fiber quality enhancement. Results: Forty-five F ₁ hybrids developed from nine lines and five testers were evaluated along with their fourteen parents in a randomized block design during kharif 2022–23. Analysis of variance revealed significant variability among genotypes for most traits. Mahalanobis D² analysis grouped the parents into six clusters, indicating substantial genetic divergence. Combining ability analysis showed the predominance of non-additive gene action (σ²sca > σ²gca) for most yield and fiber traits. Lines GJHV-548, GTHV-13/32 and GBHV-187, and testers GJHV-503 and GJHV-517 were identified as superior general combiners. Crosses such as GTHV-13/32 × GJHV-585, RAH-1047 × GJHV-517 and GJHV-522 × GJHV-503 exhibited high specific combining ability effects and significant mid-parent heterosis for seed cotton yield and related traits. Correlation and path analysis indicated that number of bolls per plant exerted the highest positive direct effect on seed cotton yield, followed by number of sympodia and boll weight. Conclusions: The predominance of non-additive gene action and the presence of high heterosis in specific crosses highlight the effectiveness of heterosis breeding in cotton. Selection based on boll number per plant, along with exploitation of genetically diverse superior combiners, can accelerate the development of high-yielding cotton hybrids with improved fiber quality.