The addition of 0.5 mM ascorbic acid (AsA) to the hydroponic growth solution of
young soybean cultivars, cvs (Glycine max Exford, high sensitive and G. max Giza
21, low sensitive) under normal growth, conditions provided protection against
subsequent salinity stress. This observation was confirmed by fresh and dry matter
contents, dose of response, total water content photosynthetic pigments, transpiration
rate, AsA contents, membrane stability index, K+ leakage and minerals (Na+, K+
content, translocation, uptake and K+/Na+ ratio). In addition, analysis of antioxidant
enzymes showed that AsA pretreatment causes an increase in catalase (EC 1.11.1.6),
ascorbate peroxidase (APX) (EC 1.11.1.11) and guaiacol peroxidase (EC 1.11.1.7)
activities under salinity stress. The seedlings of two soybean cultivars differing in salt
sensitivity were treated with 0.1, 0.2 and 0.4 M NaCl for 3 days.