Electrolyte leakage
Electrolyte leakage was used to assess membrane permeability. This
procedure was based on Lutts et al. (1996). Electrolyte leakage was measured
using an electrical conductivity meter (CC-501, Elmetron, Zabrze, Poland).
Ten leaf discs of five randomly chosen plants per replicate sample were taken
from the youngest fully-expanded leaf before harvesting and drying. After
three washes with distilled water to remove surface contamination, the leaf
discs were then placed in a test tube containing 10 ml distilled water. These
samples were incubated at room temperature, on a shaker, for 24 h. Electrical
conductivity (EC) of the solution (EC1) was then read after incubation. The
same samples were then placed in a boiling water bath for 20 min and a second
EC reading (EC2) was taken after cooling the solution to room temperature.
Electrolyte leakage was then calculated as: EC1/EC2 and expressed as a
percentage.