Hidrogel na mitigação do estresse hídrico e potencial de recuperação em mudas de Eugenia myrcianthes Nied

Abstract

The low or high water availability may cause damage to the photosynthetic and enzymatic metabolism of native species from Cerrado, such as Eugenia myrcianthes Nied. Thus, the knowledge of technologies that may mitigate stress damage is necessary for its ex situ cultivation. The aim was to evaluate the potential of hydrogel (H) to mitigate water stress and help it in the recovery of Eugenia myrcianthes Nied. seedlings under water fluctuations. Seedlings were separated into three water regimes: R1) continuous irrigation (control), R2) Intermittent stress: characterized by two stress cycles, the first being water restriction, and the second flooding (Stress) and R3) Intermittent stress + hydrogel (Stress + H). Evaluations were carried out in six periods: zero time, 1st zero photosynthesis (F0), 1 st recovery (REC), 2nd F0, 2nd REC and FINAL. Photochemical, morphological and antioxidant characteristics were evaluated. E. myrcianthes seedlings responded to water fluctuations, presenting reduction of CO2 assimilation rate, transpiration and stomatal conductance during stressful conditions. We verified decrease in the growth characteristics of this species, such as leaf area and reduced biomass in times of stress. The use of H helped to increase the intrinsic water-use efficiency by the plant and decrease the presence of antioxidant agents. We verified recovery potential for the most of evaluated characteristics. We concluded that E. myrcianthes seedlings showed morphophysiological changes regarding water deficit and flooding, but the hydrogel contributed to relief the water deficit over gas exchanges and it did not affect flooding. Seedlings showed survival, resumption of metabolism and growth after stressful conditions, demonstrating resilience due to physiological plasticity, regardless of using H.