Does hydrogel help in the mitigation and recovery of Eugenia myrcianthes Nied. under water stress?

Abstract

Water deficit or flooding can damage the photosynthetic and enzymatic metabolism in plants such as Eugenia myrcianthes Nied. Thus, knowledge of technologies that can mitigate stress damage is necessary for the ex-situ cultivation of these species. This study evaluates the potential of hydrogel (H) to mitigate water stress and assist in the recovery of E. myrcianthes seedlings under different water conditions. The seedlings were separated into three water regimes: R1 - continuous irrigation (control); R2 - intermittent stress, characterized by two stress cycles: water restriction followed by flooding (stress); and R3 - intermittent stress + hydrogel - Forth^® gel (stress + H). Evaluations occurred in six periods: zero time (T0), 1^st zero photosynthesis (P0), 1^st recovery (REC), 2^nd P0, 2^nd REC, and END. E. myrcianthes seedlings responded to water conditions with reduced CO₂ assimilation rate, transpiration, and stomatal conductance during stressful conditions. We observed decrease in the growth parameters of this species under stress, including leaf area and biomass. Under stress, independent of H, plants increased the activity of the enzymes superoxide dismutase, peroxidase, and the content of the amino acid proline. We observed recovery potential in most of the evaluated traits. E. myrcianthes seedlings showed morphophysiological changes due to water deficit and flooding. Still, hydrogel did not contribute to alleviating the effects of water deficit on gas exchange and did not affect flooding. Seedlings showed survival and resumption of metabolism and growth after stressful conditions. This demonstrates their resilience due to physiological plasticity, regardless of the use of hydrogel.