Variability in the concentration of mineral elements and phytochemical contents of cowpea genotypes for crop improvement

Cowpea (Vigna unguiculate L.) is an important legume crop due to its nutritional value and it has the potential to contribute to the alleviation of malnutrition in the world. The study objectives were to determine the variability among 70 cowpea genotypes for the concentration of mineral elements and phytochemical contents, identify superior genotypes for mineral elements and phytochemical contents, and to determine the correlation among traits. Data were collected from 70 cowpea genotypes planted in two different locations during the 2017/18 and 2018/19 cropping seasons in South Africa. Grain samples were analysed for selected minerals such as Fe, Zn, Ca, Cu, K, Mg, Mn, Na, P, and phytochemical contents including total phenolic and flavonoid. Genotype, locations, seasons, and their interaction effects were highly significant (p < 0.001) for all traits. Best linear unbiased predictors identified superior genotypes for all traits in both locations. There were significant (p < 0.05) correlations among most of the traits evaluated. The high negative association of total phenolics with most of the minerals indicated that selecting for total phenolics may unintentionally reduce the content of minerals. These results will contribute to the development of improved cowpea cultivars for nutritional value towards alleviating malnutrition in the world.