The plasma membrane permeability of the soybean root system was determined using the Conductivity Meter of Hanna EC215 (Hanna, Portugal, Italy). The untreated roots were washed with
distilled water 2e3 times, placed in a plastic cuvette with 10 mL of
distilledwater, and shaken for 2 h under 20e30 C in order to release
electrolytes formeasuring the first conductance. Then, the rootswere
boiled for 5 min until the plasma membrane was destroyed
completely to measure the second conductance. The value of plasma
membrane permeability was the ratio of the first and second
conductance.