Efeito do enxofre na absorção de selênio em feijoeiro comum

Abstract

Selenium (Se) is a deficient element in Brazilian soils and in human nutrition, and because of its essentiality to humans and animals, the application of Se in soil is one of the main alternatives to increase the bioavailability of Se in crops. The chemical similarity between sulfur (S) and Se especially concerning their fo rms and compounds, leads them to compete with each other in the processes of absorption, translocation, and assimilation in the plant. The aim of this study was to evaluate the effect of combination of doses of Se and S in the absorption of these elements and in the development of common bean (Phaseolus vulgaris L.). The experiment was conducted under greenhouse conditions in pots of 5 dm 3 filled with soil. The plants were arranged in a completely randomized design installed in a factorial design 3 x 5, with three doses of S (0, 45 and 90 mg dm -3 ) and five doses of Se (0, 0.5, 1.0, 2.0 and 4.0 mg dm -3 ) with four replicates. The plants were conducted until maturation and after harvest, shoot and grain were separated, weighed and analyzed for Se, S and N content. Adsorption and desorption tests was carried out in samples of the incubated with S at the same doses added to the pots (1:10 soil/solution). The results indicate that Se and S can interact within the plant and affect concentration of each other in bean plant tissues. T he Se supply up to the dose of 2.0 mg dm -3 stimulates the vegetative growth, concentration and accumulation of S in the shoot dry matter. The increase of the doses of Se reduces the grain production, except in the treatments with 90 mg dm -3 of S up to the dose of 1.63 mg dm -3 of Se. A synergistic relationship between Se and S stimulate the absorption and accumulation of Se in the organs of the plant. The addiction of S to the treatments reduced the Se/S and N/S ratios, while the application of Se to the treatments increased the Se/S ratio within the plant, reducing the grain production. The results of the adsorption and desorption tests indicated that there is an increase in the Se adsorbed and desorbed amounts upon enhancing Se concentrations added in solution. The treatments without S present higher Se adsorption than the treatments with S. The higher Se adsorption directly influences t he reduction of Se content and accumulation in common bean.