Ecophysiological behavior of Eucalyptus grandis x Eucalyptus urophylla, Igaratá, SP - Brazil

Abstract

This study aimed to characterize the effects of environmental variables on the transpiration (E), stomatal conductance (Gs) and photosynthesis (A) behavior of Eucalyptus grandis x Eucalyptus urophylla clone in the leaf scale over three consecutive days. The measurements were performed in a clonal population of 60 months of age, located in the municipality of Igaratá-SP. Measurements of predawn leaf water potential (Ψpd) by the Scholander pressure chamber and ecophysiological measurements of E, Gs and A were obtained by porometer LcPro + (ADC). Specific climate characteristics to the measurement days were obtained from the automatic weather station Campbell Scientific Inc. installed on the site of study, distant 100 m from the clonal settlement of interest. Environmental variables such as photosynthetically active radiation (Qleaf) and a pressure deficit of water vapor (VPD) were chosen to correlate with E, Gs and A. The best associations were observed between E, G, A with Qleaf not being significant for Gs and VPD. The ratio A / E was progressively increased with the decrease of Ψpd. Knowledge of water use efficiency helps to select the best species of Eucalyptus to determine certain conditions.