Assessment of heterosis and combining ability for yield and oil traits in cotton (<i>Gossypium hirsutum</i> L.) contributing to the revival of India's cotton sector

Cotton is a major commercial crop with global importance, especially in the textile sector. Enhancing its yield and fibre quality through hybrid breeding is a key goal in crop improvement. This study was conducted during Kharif 2024 at Lovely Professional University, School of Agriculture, Genetics and Plant Breeding Research Farm in Phagwara, Punjab, to evaluate combining ability, gene action, and heterosis in cotton (Gossypium hirsutum L.). A total of 24 F1 hybrids were developed using 10 cotton genotypes (6 lines and 4 testers) along with a standard check (G. Cot. Hy 18) in a line × tester design. Analysis of variance revealed significant variability in seed yield, boll weight, and fibre quality traits, indicating potential for improvement. Non-additive gene action was observed for seed yield, boll production, and fiber quality, whereas additive gene action was prominent for earliness traits like flowering and boll bursting. The lines 761H20 and GJHV-510, along with the tester Sanjay (CJ-73), were identified as effective general combiners for seed yield, boll weight, and fiber quality. Among the hybrids, 761H20 × V-797, GJHV-503 × Guj. Cot.-15, and 761H20 × Deviraj stood out as the top performers, exhibiting strong performance, high SCA effects, and improved heterosis for yield and fiber traits. Additionally, the hybrid GJC-101 × V-797 showed excellent performance in boll production and weight. These hybrids have strong potential for commercial through heterosis breeding.. The variance ratio (σ²GCA/σ²SCA) being less than one confirmed the predominance of non-additive gene action. This study provides insights for developing superior cotton hybrids.