Electrolytic leakage was determined on 12 square bract portions (1 cm × 1 cm) for each treatment sample. The pieces were washed three times for about 1 min each in distilled H2O and blotted dry. Groups of four bract portions (∼2 g total) were then put into individual 50 mL plastic tube with 20 mL of 0.5 M mannitol solution (isotonic concentration previously determined according to the method of