2.4. Electrolyte leakage
Leaf disks of 2.5 cm in diameter were excised from the lowest leaves for EL determination according to the modified methods of Mao et al. (2007). After being rinsed 3 times for 2–3 min with de-ionized water, 5 pieces were put into 20 ml of de-ionized water in test tubes and shaken every 5 min for 30 min. Conductivity was measured using a conductivity meter. Total conductivity was obtained after keeping the test tubes boiling for 15 min and electrolyte leakage was expressed as percentage of total conductivity.