Respostas fisiológicas e bioquímicas de plantas de aroeira ao défice hídrico e posterior reidratação.

Abstract

Water stress affects plants in several ways, depending on its intensity and duration, and the ability of plants to withstand these conditions is critical to its establishment. The aim of this study was to evaluate gas exchange and accumulation of organic solutes in young aroeira plants (M. urundeuvaAllemão) subjected to water stress and subsequently to rehydration. 12 months old plants, kept in black plastic bags containing 5 kg of a mixture of soil and manure (2:1) were submitted to the irrigated treatments (control) and drought stress, which was imposed by suspending irrigation. After 12 days of stress, plants were rehydrated. Plants under water stress presented relative water content of 70 % at the end of the stress period.The water deficit promoted progressive reduction in stomatal conductance, transpiration, net photosynthesis and in the efficiency in water use. The intercellular CO2 concentration, leaf concentrations of total sugars and total soluble amino acids increased. After resumption of irrigation, rapid recovery occurred in relative water content, but the recovery in stomatal conductance and netphotosynthesis occurred more slowly. The aroeira plants are able to recover the water status and functioning of stomata and photosynthetic mechanism after rehydration, showing tolerance to water stress.