Growth, survival and gas exchange in Eucalyptus dunnii Maiden plants submitted to irrigation regimes and hydrogel application

Abstract

The addition of water-repelling polymers aims to increase water retention capacity in the soil, providing higher seedling survival rate and allowing planting at different times of the year. The objective of the present work was to evaluate the effect of hydrogel use on planting Eucalyptus dunnii seedlings in pots, related to different water management, simulating field conditions in a  Humic Cambisol soil. The experiment was conducted in a completely randomized design with factorial arrangement (hydrogel and irrigation frequency). The hydrogel factor was composed by the presence or absence of the polymer, and the frequency of irrigation by irrigation only at planting, every 8 days, 4 days and daily. Water stress symptomatology, morphometric aspects, soil water content and gas exchange were evaluated. The hydrogel provided an increase in soil water content and delayed symptoms of water stress, especially when irrigation was less frequent. The addition of the polymer also provided improved seedling quality, more accumulated dry mass. Water stress was a limiting factor for stomatal opening. The lower the water availability, the lower the photosynthesis, stomatal conductance and transpiration values. In general, the results confirm that the addition of hydrogel in the soil optimizes water availability, with the possibility of reducing planting mortality and maximizing plant growth in the initial phase of establishment.

Keywords: Water-repelling polymer, water deficit, ecophysiology, photosynthesis, symptomatology.