Consequências do estresse salino em mudas de Erva-Mate (Ilex paraguariensis St. Hil.)

Abstract

Plants are susceptible to suffering from abiotic stresses in their environment, with saline stress being one of the most harmful, causing various negative consequences in plants that lack tolerance. The effect of salinity remains unknown in many plant species, including yerba mate (Ilex paraguariensis), a native plant of the Atlantic Forest belonging to the Aquifoliaceae family and that holds immense cultural, socioeconomic, and ecological influence in the Southern region of Brazil. Therefore, the objective of this study was to evaluate the tolerance levels and consequences of salinity on Ilex paraguariensis seedlings subjected to different concentrations of NaCl. The study was divided into two experiments: the first involved plants exposed to five NaCl concentrations (0 mM, 50 mM, 100 mM, 150 mM, and 200 mM) for seven days, followed by the measuring of chlorophyll fluorescence and chlorophyll content. In the second experiment, plants were exposed to a single saline concentration (200 mM) and a control (0 mM) also for seven days, followed by analyzes of chlorophyll content, chlorophyll fluorescence parameters, relative water content, and electrolyte leakage. The results indicated that plants treated with NaCl compared to the control presented a reduction in chlorophyll content and indicators of photochemical efficiency. However, there was no reduction in relative water content, indicating that yerba mate probably did not suffer from water stress consequences related to salinity. Overall, yerba mate showed moderate tolerance to the saline conditions it was exposed to. This study was key in understanding the consequences of salinity in this species, particularly for crop production and potential adaptation to climate change in the region. For future studies, biochemical assays are suggested to better comprehend the mechanisms affected by saline stress and associated tolerance strategies in yerba mate.