Selenium biofortification of soybean in oxidic soil: genetic and agronomic approaches

Abstract

Selenium (Se) is an important micronutrient for humans and animals and its deficiency is widespread worldwide. Enhancing Se concentration in staple crops through biofortification (agronomic and genetic) may be an effective strategy to alleviate human malnutrition. Soybean (Glycine max L. Merril) is a crop with a great potential for that, since is a protein-rich food and is largely used to animal feed, consequently reaching humans. This study evaluated the biofortification potential of two soybean varieties with Se, thru the application of phosphat e fertilizer coated with Se. The experiment was conducted under greenhouse conditions, in the Soil Science Department at Federal University of Lavras, Lavras (MG), Brazil, on a dystrophic Red Latosol. The experimental design was a completely randomized block design, in a factorial scheme 2 x 3 x 2, with two sources of phosphate fertilizer ( a conventional monoammonium phosphate and an enhanced-efficiency monoammonium phosphate), used as carriers for adding Se in the soil, three rates of Se (0, 0.1, and 0.2 mg dm -3 ) and two soybean genotypes (cv. 58I60RSF Lança and cv. M5917 IPRO). Plant height, nodes number, branches number, pod number, leaf dry matter, steam dry matter, pod dry matter, macronutrients and micronutrients content, Se content in the plant tissue, and grains yield were evaluated. In addition, the soil solution was collected at 7, 14, 28, and 56 days after sowing for the determination of P, K, Ca, Mg, S, Fe, Mn, Cu, Zn, and Se. The obtained data were tested for their normality by the Shapiro Wilk test, submitted to analysis of variance, and when significant, the averages were compared by the Tukey test at 5%. For the content and accumulation of Se in the grains, there was significant difference by the F test for the interaction between sources of phosphate fertilizers and rates of Se applied. The contents of Se in the soybean grains increased upon increasing the Se application rate. Grains yield was influenced by rate, with the highest rate (0.2 mg dm -3 ) decreasing crop yield. Thus, we conclude that coating phosphate fertilizer with Se is an efficient agronomic strategy for biofortification of soybean grains with Se in oxidic soils. In addition, the rate of 0.1 mg dm -3 was the most indicated among the rates tested, since this dose favored the biofortification of the grains without decreasing crop yield.