The effects of water stress and rehydration on the fluorescence parameters, stomatal conductance, lipid peroxidation of Myracrodruon urundeuva Fr. All. (Anacardiaceae) plants were investigated. The plants were grown under greenhouse conditions and drought was induced by 14 days of witholding water. Under water stress the relative leaf water content decreased by up to 60 %. This decrease was associated with the decrease in stomatal conductance values and apparent photosynthetic electron transport rates (ETR) and extensive damage to membranes due to lipid peroxidation. Despite the decrease in ETR, no change in the potential quantum yield of Photosystem II (Fv/Fm) was observed as consequence of water stress. Following a recovering phase, the plants showed stomatal conductance, fluorescence parameters and lipid peroxidation values similar to those prior to drought induction. All photosynthetic parameters investigated showed normal values up to 6 h after the onset of rehydration. A linear relationship fitted to stomatal conductance and ETR showed that these two variables are highly correlated suggesting that stomata are the main limiting factor to photosynthesis in M. urundeuva plants under water stress.
Fluorescence; Myracrodruon urundeuva; oxidative stress; photosynthesis; stomatal conductance
