Comprehensive Analysis of Combining Ability and Genetic Parameters for Green Fodder Yield and Quality Traits in Indian Cowpea (Vigna unguiculata L.)

Target traits in hybrid breeding programs are crucial as they are highly responsive to gene action and combining ability. The line × tester method aids in understanding the genetic interactions influencing these traits, enabling the development of superior hybrids by selecting parent combinations that optimize heterosis or hybrid vigor. The study involved 23 forage cowpea genotypes and 3 testers, resulting in 69 F1 hybrids produced at Tamil Nadu Agricultural University, Coimbatore. The experiment was conducted over two cropping seasons (2023–2024) at the New Area Farm Experimental Station. A Randomized Complete Block Design (RCBD) with three replications was employed. The line × tester interaction was highly significant for all traits, indicating the impact of additive and non-additive gene expression variations. Notably, specific genotypes displayed significant General Combining Ability (GCA) effects: GETC 21 for Crude Protein (CPR), GETC 49 for Number of Leaves (NOL) and CPR, and CL 348 for Dry Matter Yield (DMY) and Crude Fiber (CFR). Additionally, hybrids demonstrated substantial Specific Combining Ability (SCA) effects, particularly CS 98 × CO 9 and CL 321-1 × CO(FC) 8 for DMY, and GETC 49 × CO(FC) 8 and GETC 49 × CO 9 for days to fifty percent flowering (DFF). Mid-parent heterosis was evident, with IFC 9402 × CO(FC) 8 showing the highest heterosis for plant height and FD 1052 × TNFC0926 for CPR. These results underscore the importance of selecting lines and testers with high GCA and hybrids with high SCA to enhance Green Forage Yield (GFY), DMY, CPR, CFR, and NOL in forage cowpea. This approach promises the development of new, high-yielding, and nutritionally superior cowpea varieties.