Does silicon inEugenia myrcianthes Nied. seedlings under water stress contribute in the tolerance and recovery?

Abstract

Purpose: Silicon (Si) could contribute to the stability of photosystem II processes and gas exchange. Moreover, it can increase antioxidant enzyme activity, maintaining the growth of E. myrcianthes under water fluctuation, favoring seedling tolerance and recovery after stress suspension. This study aimed to evaluate the silicon effect on E. myrcianthes subjected to water fluctuation and the potential recovery of photosynthetic and enzymatic metabolism and seedling growth after stress suspension. Methods: Two water regimes: continuous irrigation (I), with 75% of the water retention capacity of the substrate, and water stress (E), with irrigation suspension followed by flooding. The water regimes were associated with different Si concentrations: 0, 2, and 4 mmol L-1. The seedlings were evaluated in five periods: Time zero (T0), with initial evaluations and irrigation suspension; First photosynthesis close to zero under water deficit - 1st P0; First recovery - 1st REC; Second photosynthesis close to zero under flooding - 2nd P0; Second recovery - 2nd REC. Results: Water fluctuation negatively affected the photosynthetic and enzymatic metabolism of E. myrcianthes. However, we observed 100% survival of all seedlings, suggesting the physiological plasticity of the species. Applying 2 mmol L-¹ of silicon to the seedlings helped them tolerate the stressful effect of water fluctuation. Conclusion: Water stress decreased the development of E. myrcianthes seedlings, damaging the photochemical and biochemical metabolism of photosynthesis, increasing antioxidant enzyme activity, and reducing root growth and seedling quality. However, Si application at concentrations of 2 mmol L-¹ mitigated water stress effects, favoring seedling development and tolerance to water fluctuation. The species can adjust to stressful conditions and shows potential for survival and tolerance at this developmental stage, recovering its metabolism and growth after stress.