Embolism vulnerability of an evergreen tree

Abstract

Leaf bearing stems of Curatella americana L. were very susceptible to induced cavitation: embolisms began at a pressure of 0.5 MPa (15 %) and at 2.0 MPa most of the conductivity was lost (85 %). Nevertheless, in nature similar leaf specific conductivities, of about 90 × 10-5 kg m-2 s-1 MPa-1 during both wet and dry seasons indicated absence of drought induced embolisms. Leaf water potentials were neither very negative or considerably different between seasons but stomatal conductance decreased from 236 mmol m-2 s-1 measured during wet period to 100 mmol m-2 s-1 during drought season. Therefore, it was concluded that Curatella had an accurate homeostatic balance of leaf water status to keep up xylem integrity.