Unraveling heterosis and combining ability for enhancing yield and its component traits in Cowpea (Vigna unguiculata L. Walp)

The present study explores heterosis, combining ability, gene action, and proportional contribution of lines, testers and their interactions for yield and its contributing traits in cowpea (Vigna unguiculata L. Walp). Evaluating 24 F1 populations, 11 parents (3 lines and 8 testers), and a standard check (Phule Rakhumai) in Randomized Block Design during Summer 2024. The results revealed that line PL 4, tester NIC 23105, and crosses, PL 4 × IC 259084, Phule Vithai × IC 263015, and Phule Sonali × EC 738083, were found superior for yield and its component traits based on GCA and SCA estimates, respectively. Further, PL 4 × IC 259084, PL 4 × NIC 23105, Phule Vithai × IC 263015, Phule Sonali × NIC 23105, and Phule Sonali × V 240 were identified as superior crosses for yield/plant based on estimates of standard heterosis. The gene action studies indicated that non-additive gene action predominantly controls most quantitative traits, as the dominant variance (σ2 D) was more than the additive variance (σ2 A) and the variance ratio was less than unity for most of the quantitative traits except days to maturity and 100 seed weight. While the higher contribution of line × tester interactions also highlighted the effective role of testers. Heterosis breeding can thus be commercially exploited to develop superior cowpea hybrids.