Aplicação de iodo como estratégia para mitigação do estresse do déficit hídrico nas plantas

Abstract

As ongoing climate changes, marked by irregular precipitation patterns, pose a severe threat to food security, raising significant concerns about their impact on the food chain. Water deficit emerges as a critical factor for global agricultural stability and productivity. This deficit is a complex stressor affecting various morphophysiological characteristics throughout growth stages, resulting in considerable economic losses. Consequently, there is a growing exploration of new technologies and management practices to mitigate the damages caused by water deficit. The exogenous application of chemical elements has been considered a promising strategy to alleviate water deficit stress in plants, with special attention to elements classified as beneficial, such as selenium and silicon. However, certain elements in this category, like iodine, have been underexplored, despite demonstrating potential in mitigating other environmental stresses, such as saline stress and heavy metals. Thus, we conducted studies to assess the effectiveness of iodine applied in the form of potassium iodide (KI) via nutrient solution in mitigating water deficit in tomato and soybean plants. In the first experiment, we subjected tomato plants to water deficit and three concentrations of KI (0, 50, and 100 μM KI). We observed that exposing tomato plants to a concentration of 100 μM KI reduced oxidative damage caused by water deficit, increased photosynthetic efficiency, productivity, and improved fruit quality. In the second experiment, we applied increasing concentrations of KI (0, 10, 20, and 40 μM KI) to soybean plants grown under water deficit. It was possible to observe that KI at low concentrations (10 μM KI) promoted greater tolerance to water deficit in soybean plants, increasing photosynthetic efficiency, enzymatic antioxidant protection, and consequently biomass accumulation. However, at high concentrations (40 μM KI), phytotoxicity occurred, resulting in a reduction in the photosynthetic rate and biomass accumulation. We concluded from both studies that, when applied at the ideal concentration, iodine can increase plant tolerance to water deficit, inducing enzymatic antioxidant responses and promoting photosynthetic gains, which, in turn, lead to increased productivity. Additionally, this element also demonstrated the potential to improve fruit post-harvest quality. Our findings not only highlight the immediate benefits of iodine supplementation in plants grown under water deficiency but also elucidate some of the processes through which this element operates under these conditions. These studies represent a significant scientific advancement, providing a comprehensive understanding of iodine's multifaceted contributions to plant adaptation in water-scarce environments. Our work not only contributes to the scientific community but also offers transformative applications in agriculture, fostering a discourse on ensuring food security through innovative techniques.