Phenotypic diversity among cowpea mutants and accessions for grain yield and yield components

Abstract

Phenotypic characterization of cowpea germplasm collections is an essential step for the cowpea genetic improvement. The objectives of the study were to determine the phenotypic diversity and characterize cowpea mutants and accessions for grain yield and yield components, to identify their superiority, and to determine the correlation between measured characteristics. Thirty-one cowpea genotypes (16 Namibian mutants, seven International Institute of Tropical Agriculture (IITA) genotypes and eight South Africa genotypes) were planted in five different environments in South Africa during the 2021/2022 cropping season. Significant (P ≤ 0.05) genotype, environment and genotype by environment interaction effects were observed for all grain yield and yield components. Moderate to high broad-sense heritability (H2) (> 50%) was observed for all yield components. Superior Namibian Mutants (ShR10P12, ShR3P4, ShR4P1 and BrR11P2), IITA genotype (98K-476-8) and South African genotype (Enchore) were identified for grain yield (GY), number of seeds per plant (NSPPx), pod weight per plant (PWP) and number of pods per plant (NPP). There were significant positive correlations between most of the yield components. In the principal component analysis, Namibian mutant genotypes ShL2P7, ShR4P1, NKR1P3 and BrR11P2 were associated with high NSPPx, PWP and GY. The clustered heat map identified a group of Namibian mutants (NKR1P3, BrR11P2, ShL2P7, ShR2P11 and ShR10P12), IITA genotype (98K-47-8) and South African genotypes (Glenda, Dr Saunders, Enchore, and Oloyin) which was associated with high GY, PWP, NSPPx, NPP, seed weight per plant (SWP) and harvest index (HI). The identified superior cowpea mutants for grain yield and yield components can be used for cowpea improvement.