Variation in Grain Mineral Concentrations of 63 Common Bean Genotypes Planted at Malkerns, Eswatini, in Africa

Abstract

Low soil mineral concentrations are a major limitation to the nutritional quality of grain crops produced in Africa. As a result, 232 million people are suffering from microelement deficiency and 239 million from protein-calorie malnutrition in Africa. This study evaluated the nutritional quality of common bean grain harvested from 63 genotypes planted at Malkerns in Eswatini. The results showed significantly marked differences in the concentrations of 10 dietarily important nutrient elements. Of the macronutrients, Na levels showed the highest variation (12.00–91.00 mg/g) among the 63 bean genotypes, followed by K (14.03–22.03 mg/g) and P (3.30–9.57 mg/g), with Mg (1.57–2.30 mg/g) and Ca (0.80–2.68 mg/g) concentrations exhibiting the least difference among the bean genotypes. Of the micronutrients, Fe levels revealed the highest variation (66.36–151.08 mg/kg), followed by Zn (23.57–70.72 mg/kg) and Mn (11.53–26.84 mg/kg), with B (10.06–17.65 mg/kg) and Cu (6.30–13.67 mg/kg) exhibiting relatively lower differences among the 63 common bean genotypes. However, genotype NUC 461 recorded the highest grain concentrations of P, K, Mg, Fe, Cu, Zn, and B, followed by DAB 155, which also revealed high levels of P, K, Ca, Fe, Zn, and Mn in its seeds. For improved human health and nutrition, the two bean genotypes would be the ideal candidates to recommend to commercial bean growers and resource-poor farmers. However, the mechanisms underlying the greater accumulation of six to seven dietarily important nutrient elements by genotypes NUC 461 and DAB 155 remain to be determined.