Effects on food-type soybean cultivars when biofortified with different rates of zinc

The objective of this research was to verify the effect of biofortifying food-type soybean grains with different foliar applied zinc rates. The experiment was completely randomized with four replicates, in a 5 × 5 factorial scheme, which consisted of five soybean varieties: BRS 010 (black tegument), BRS 213 (yellow), BRSMG 790A (yellow), BRSMG 800A (brown), and Favorita RR® (yellow) combined with five zinc foliar rates applied at the reproductive 4 (R4) stage (0, 0.91, 1.82, 2.73, and 6.37 mg L-1). The analyzed parameters were plant height, first pod insertion height, number of pods per plant, number of grains per plant, pod weight per plant, grains mass per plant, 100-grain dry matter, mineral composition of the grains, lipid and protein content. Foliar fertilization with zinc increased plant height, grain mass, and protein content in soybean grains. It also significantly increased zinc content in the grain and this increase was independent of the studied variety, but was a function of the zinc rate applied.