Photosynthesis and leaf protoplasmatic tolerance in Myracrodruon urundeuva

Abstract

The Myracrodruon urundeuva Fr. All. (Anacardiaceae) is known as aroeira-do-sertão and is natural of Caatinga, Cerrado and Atlantic Rain Forest. Photosynthesis and transpiration rates, stomatal conductance, relative water content and leaf protoplasmatic tolerance were measured on five months old plants grown under greenhouse conditions and submitted to two water supply regimes: daily irrigation and no water supply during five days. Evaluations were made in leaves of apical, intermediary and basal position of plant. The water deficit promoted increment in relative water content in leaves of all positions as also reduced photosynthesis rate. The apical leaves were the most sensitive to water supply regimes. At higher temperature the leaves located at intermediary position in stem showed higher protoplasmatic tolerance.