O papel do selênio na cultura do gergelim (Sesamum indicum L.): potencial de biofortificação e na mitigação dos efeitos do estresse hídrico

Abstract

Sesame (Sesamum indicum L.) has gained prominence in recent years on both national and international stages due to the nutritional value of its seeds and their high content of high-quality oil. In this context, selenium (Se) emerges as a strategic element, being essential for human health and exhibiting beneficial effects on plants, especially under adverse conditions. The objective of the first study was to evaluate the potential of agronomic biofortification with selenium in sesame cultivation. The experiment was carried out using a randomized block design in a 2 × 5 factorial scheme with four replications. Treatments consisted of five Se doses (0, 25, 50, 100, and 200 μg pot), applied as sodium selenate (Na₂SeO₄), in two sesame cultivars (BRS Anahí and Seda). The variables assessed included shoot and seed dry matter, productivity, and translocation of Se and other essential plant nutrients. Statistical analysis was performed using ANOVA, and means were compared using Tukey’s test (p ≤ 0.05). Se application positively impacted grain yield, increasing productivity by up to 40% at the 25 μg per pot dose. The Se content in the grains increased with higher application doses, demonstrating the viability of agronomic biofortification. The 25 μg per pot dose was the most suitable, as it enhanced both productivity and nutritional quality without causing adverse effects on the crop. The second study aimed to investigate how different Se sources influence sesame’s tolerance to prolonged water deficit, assessing physiological, biochemical, nutritional, and productive responses. The experiment was conducted in a randomized block design with a 4 × 2 factorial arrangement and four replications. Se sources (mineral, organic, and a blend of both) and a control (no Se application) were tested under two water management regimes (water deficit and irrigation). Physiological, nutritional, and yield analyses were conducted, and statistical analysis followed the same ANOVA and Tukey’s test procedure (p ≤ 0.05). Water deficit significantly affected all evaluated parameters. However, Se application showed beneficial effects—particularly with the mineral source—by promoting plant recovery after the stress period. Se accumulation in grains was efficient across all sources, although water deficit limited translocation in some cases. Nonetheless, Se alone was not sufficient to completely prevent yield losses under drought conditions, regardless of source. While it may not eliminate the negative effects of water deficit on productivity, Se helps maintain physiological functionality, activates antioxidant defenses, and allows for agronomic biofortification even in adverse environments.