Variation in seed protein, selected minerals, phytic acid, and potential mineral bioavailability of cowpea [Vigna unguiculata (L.) Walp] mutants and accessions

Abstract

Cowpea [Vigna unguiculata (L.) Walp] has the potential to contribute to the eradication of hunger and malnutrition. The study objectives were to evaluate the variability of cowpea mutants; International Institute of Tropical Agriculture (IITA) and South African genotypes for protein content, selected minerals, phytic acid, and the bioavailability of iron (Fe) and zinc (Zn); to identify superior cowpea mutants, IITA, and South African genotypes; and to determine the correlation between measured characteristics. A total of 31 cowpea genotypes were planted at five different environments in South Africa. Significant (p ≤ 0.05) genotype and genotype by environment interaction effects were observed for protein, minerals, and phytic acid concentration. High broad-sense heritability (>50%) was observed for almost all the characteristics. Thirteen Namibian mutants, five IITA genotypes, and six South African genotypes that combined high protein, Fe, and Zn were identified. The IITA genotype IT93K-452-1 and South African genotypes Oloyin and Orelu had good Fe bioavailability. Nine Namibian mutants, four IITA genotypes, and three South African genotypes were associated with high values for protein, manganese, phytic acid, molar ratios of phytic acid with Fe and Zn, and ash. The identified superior cowpea mutants, IITA and South African genotypes could be a good source of the essential minerals and should be further studied for adaptability in South African agroecologies.