Combining Ability and Hybrid Performance of Cowpea Landraces Under Semiarid Conditions

Cowpea (Vigna unguiculata (L.) Walp.) plays a key role in food security and income generation in semiarid regions, particularly for smallholder farming systems in the Brazilian semiarid. However, productivity remains low because of environmental limitations, genetic constraints, and traditional crop management practices. We evaluated diallel crosses among cowpea landraces to identify superior parents and cross combinations in terms of earliness and grain yield under semiarid conditions. Six landrace accessions, previously selected through participatory prospecting for adaptability and yield stability, were crossed in a complete diallel design to produce 15 F1 hybrids and their reciprocal crosses. The hybrids were evaluated under field conditions in the semiarid region during the 2023 growing season using a randomized complete block design with ten replications. The evaluations were conducted according to each genotype’s developmental stage and immature pod formation. Early-maturing varieties were harvested at 60 days, intermediate and late varieties between 65 and 75 days. At physiological maturity, early and intermediate genotypes were harvested at 80 days, while late genotypes were harvested between 85 and 90 days. General combining ability (GCA) and specific combining ability (SCA) were estimated using Griffing’s Method I (fixed-effects model), and treatment means were compared using the Scott–Knott test at the 5% significance level. Significant GCA and SCA effects (p < 0.05) were detected for 12 of the 14 evaluated traits, whereas reciprocal effects were significant for seven traits. The hybrid combinations L1 × L4, L1 × L5, and L4 × L5, and their reciprocal crosses, exhibited superior agronomic performance, highlighting their potential as valuable genetic resources for cowpea breeding under semiarid environments.