Biofortificação de ora-pro-nobis (Pereskia aculeata Mill.) com selênio via solo

Abstract

The ora-pro-nobis (Pereskia aculeata Mill.) is an unconventional food plant (PANC) that has great nutritional value in its leaves, being consumed in several dishes, in addition to being used as a medicinal plant. In this sense, a strategy to increase its nutritional value and make it contribute to minimize problems of nutritional deficiencies in the human body is agronomic biofortification with selenium, a nutrient that is considered one of the most deficient in the human population and that helps in the prevention of various diseases. Given the above, this study aimed to evaluate the biofortification potential of ora-pro-nobis (Pereskia aculeata Mill.) with selenium, as well as the effect of this element in different doses on its agronomic performance and nutritional quality. The experiment was conducted in a greenhouse, following a completely randomized design, in a 6 x 2 factorial scheme, with two sources of selenium (selenate and selenite) applied via soil, six doses (0; 0.5; 1.0; 2.0 ; 4.0 and 8.0 mg of Se kg-1 of soil), with four repetitions, totaling 48 experimental plots. With the increase in Se doses, there was a decrease in the production of fresh leaf and stem dry matter, in the treatment with selenate, also decreasing the lipid content of the leaves. In the ash variable, independent of the sources, up to the 4.0 mg kg-1 dose of Se, there was an increase in it and, from that dose, the ash content remained constant. The effect of applying Se on the carbohydrate content was significant only when selenate was applied, decreasing up to the dose 1.0 mg kg-1, remaining constant until the dose 4.0 mg kg-1 and, from there, with increasing dose, there was a small increase in this variable. Selenium was able to affect the nutrient content in the leaves, while sulfur and iron increased with a dose of 2.0 mg kg-1 of Se in the form of selenate and 4.0 mg kg-1 of Se in the form of selenite, respectively. The Mg content was affected at 1.0 mg kg-1 when selenite was applied and at 8.0 mg kg-1 when selenite was applied, reducing the absorption of this element by plants. Its leaves were able to absorb total levels of Se close to 850 mg kg-1 with the source of selenate, in the maximum applied dose (8.0 mg kg-1 of Se). Despite this, this element caused toxicity in the plants, which reflected in the impairment of its growth, leading to the appearance of toxicity symptoms. The species can be classified as a Se accumulator, since it was able to accumulate between 100 and 1000 mg kg-1 of Se in its tissues. However, despite this possible classification, in the doses in which the plants were able to accumulate high concentrations of Se with the selenate source, toxicity occurred in the plants, which shows that the fact that they accumulate a lot of Se in their tissues was not interesting, since that caused physiological and production damage to them.