Biofortification of potato with selenium and its influence on physiological aspects

Abstract

Selenium (Se) is a micronutrient for humans and animals, composing several selenoproteins and acting on the antioxidant system. Although their need for daily intake is low, part of the world population has deficiency of this micronutrient in blood plasma. In order to increase the intake of Se by the world population, several researches aimed at raising the content of this element in agricultural crops have been developed. For plants the Se is not essential, however, low doses benefit your antioxidant system, while higher doses can cause toxicity, as can occur in humans and animals. In this study two experiments were carried out with Se in potato plants, aiming to evaluate the effect of the application of the element on gaseous exchanges, tuber production, Se content and nutrients in plants and tubers, physicochemical characteristics (soluble solids content, titratable acidity, pH and maturation index) and antioxidant activity in the tubers. In the first experiment, two sources of Se (selenate and selenite sodium) and five doses of Se (0; 0.75; 1.5; 3.0 and 5.0 mg kg-1) were applied to the soil together with the planting fertilization, with four replicates. In the second experiment, foliar application was performed during the tuberization period, using two sources of Se (selenate and sodium selenite) and five concentrations (0; 25; 50; 75 and 100 μmol L-1); applying 200 mL per plant, with four replicates. The results of the first experiment showed that the application of selenate in low doses (0.75 e 1.5 mg kg-1) proved to be the best source of Se for the biofortification of the potato, due to having raised the contents of Se in the tubers without compromising the growth of the plants, also promoting gains in productivity. This source and doses also improved the antioxidant system and reduced the reactive oxygen species in the tubers. In the second experiment, the growth of the plants as well as the yield of the tubers were not affected by the foliar application of Se. However, Se in the form of selenate increased the internal carbon concentration, stomatal conductance, as well as increased B contents in the aerial part of the plants and increased the contents of K, S, Fe, soluble solids and SOD activity and decreased the H2O2 and lipid peroxidation in the tubers. The Se in the form of selenite was superior to selenate for the content and accumulation of Se in the aerial part of the plants and increased the concentration of H2O2 and malondialdehyde (MDA) in the tubers. Foliar application of different concentrations of Se, regardless of the source, increased its content in the tubers and caused an increase in the photosynthetic rate in plants, maturation index and peroxidase activity (POD) in the tubers. Despite the favorable effects of the application of Se in potato plants, field studies are still necessary to prove these results, since environmental factors (biotic and abiotic) may interfere with the growth, development and metabolism of plants; in order to establish ideal doses for biofortification in different regions of Brazil. It is also fundamental to conduct sensory tests to determine the acceptability of biofortified foods by consumers.