Leaf water potential (ww, MPa) was measured with a Scholander-type
pressure bomb (Plant Moisture Systems, Santa
Barbara, CA, USA). Cell membrane stability was determined
using the electrolyte leakage (EL,%). Three leaf segments of
equal size were washed and placed in sealed culture tubes
(25 9 150 mm) filled with 10 ml distilled water and shaken in
a water bath at room temperature (25 °C) for 24 h. After measuring
the electrical conductivity (EC) of the solution (EC1),
the solution with the leaf segments was autoclaved at 120 °C
for 20 min and then maintained at 25 °C for cooling (>1 h);
the second EC (EC2) was then measured (Lutts et al. 1996).
The EL value was calculated using the following equation: