Application of sodium selenate to cowpea (Vigna unguiculata L.) increases shoot and grain Se partitioning with strong genotypic interactions.

Backgorund: Cowpea is a crop widely used in developing countries due its rusticity. Besides its rich genotypic variability, most breeding programs do not explore its potential to improve elements uptake. Selenium (Se) is a scarce element in most soils, resulting in its deficiency being common in human diets. This study aimed to evaluate the interaction between biofortification with Se and genotypic variation in cowpea, on the concentrations of Se in roots, leaves + stem and grains.

Methods: Twenty-nine cowpea genotypes were grown in a greenhouse in the absence (control) and presence of Se (12.5 μg Se kg soil) as sodium selenate, in fully randomized scheme. The plants were cultivated until grains harvest. The following variables were determined: roots dry weight (g), leaves + stems dry weight (g), grains dry weight (g), Se concentration (mg kg) in roots, leaves + stems and grains, and Se partitioning to shoots and grains.

Results: Selenium application increased the Se concentration in roots, leaves + stems and grains in all genotypes. At least twofold variation in grain Se concentration was observed among genotypes. Selenium application did not impair biomass accumulation, including grain dry weight. Genotype "BRS Guariba" had the largest Se concentration in grains and leaves + stems. Genotype MNC04-795 F-158 had the largest partitioning of Se to shoots and grain, due to elevated dry weights of leaves + stems and grain, and high Se concentrations in these tissues.

Conclusion: This information might be valuable in future breeding programs to select for genotypes with better abilities to accumulate Se in grain to reduce widespread human Se undernutrition.