Vol. 9, Special Issue 8, Part K (2025)

The present study aimed to assess the general combining ability (GCA) of parental lines and the specific combining ability (SCA) of hybrids for seed cotton yield, its yield-contributing components, and fibre quality traits to facilitate the development of high-yielding cultivars with superior fibre attributes. A line × tester mating design was employed, involving four lines and twenty testers, to generate 80 hybrids. Analysis of variance revealed significant GCA and SCA effects for most traits, indicating the importance of both additive and non-additive genetic effects. Non-additive gene action was predominant for traits such as days to square initiation, number of monopods and sympods per plant, number of bolls per plant, plant height, boll weight, seed cotton yield, harvest index, 2.5% span length, fibre strength, and fibre fineness. Conversely, additive gene action was more prominent for days to maturity and ginning outturn. Among the female parents, PIL-138 exhibited strong general combining ability for number of sympods and bolls per plant, boll weight, seed cotton yield, and ginning outturn. PIL-139 showed good combining ability for fibre strength. RS 875 displayed significant negative GCA effects for earliness, monopods per plant, plant height, maturity duration, and fibre fineness-traits often desirable for specific breeding goals. Among testers, F-1040 showed good GCA for number of bolls, boll weight, sympods per plant, and seed cotton yield. EC676017 was favorable for monopods per plant and plant height, while RC-8 contributed to early square initiation. PIL-136 was a desirable tester for harvest index and ginning outturn. Notably, EC676015 was identified as an excellent general combiner for all fibre quality traits.
Hybrids showing high positive and significant SCA effects for seed yield included RS 875 × RC-85, RS 875 × PIL-135, and LH 900 × RC 240. For fibre traits, the combinations PIL-138 × EC676018, PIL-138 × EC676026, and PIL-139 × RC-85 were found to be promising based on their significant SCA effects. These results provide valuable insights for selecting superior parental lines and hybrid combinations in cotton breeding programs aimed at improving yield and fibre quality.