Pós-colheita e antioxidantes de túberas de batata-doce provenientes de mudas micropropagadas com selênio

Abstract

Sweet potato (Ipomoea batatas L.) is a crop of great importance for global food security. It is traditionally propagated vegetatively through vines or tubers. However, this method can spread viral diseases, negatively affecting productivity. As an alternative, tissue culture (TC) allows rapid and large-scale production of seedlings with high agronomic and sanitary quality. However, adaptation to the ex vitro environment represents a challenge due to susceptibility to biotic and abiotic stress, which leads to high mortality rates. In this context, the use of selenium (Se) in culture media has shown promise by stimulating the synthesis of antioxidant compounds, promoting growth and increasing plant resistance. However, Se has a narrow concentration range between benefit and toxicity, and can be harmful in high doses. Therefore, it is essential to carefully evaluate the source and dosage used, considering the specificities of the plant species. This study aimed to evaluate the postharvest quality, non-enzymatic antioxidant compounds and antioxidant enzyme activity in sweet potato tubers from micropropagated seedlings in MS medium supplemented with different concentrations of sodium selenate and selenite (5.0, 10.0, 15.0, 20.0 and 25.0 µM). The seedlings of the Campina cultivar were grown in vitro, acclimated in a greenhouse and transplanted into bags with a mixture of soil, sand and substrate. The tubers were harvested 145 days after transplanting, processed and stored at -80 °C for analysis. Se treatments, except the 25 µM concentration, resulted in firmer tubers. The concentration of soluble solids was higher between 15 and 25 µM selenate and 25 µM selenite. Titratable acidity increased with 20 µM of both sources. The maturation index was higher in the control and with 25 µM, and lower in the other concentrations of selenate. The levels of reducing sugars, total sugars and proteins were influenced by the different concentrations, with emphasis on selenite, which promoted an increase in all doses. Antioxidant compounds such as ascorbic acid and total phenols, as well as the enzymes SOD, CAT and APX, showed greater activity with 20 µM of selenate or sodium selenite. It is concluded that the addition of 20 µM of selenate or selenite in the culture medium favors the production of tubers with better post-harvest quality and greater antioxidant activity, contributing to the success of sweet potato micropropagation.