RESUMO
In the present work, hydroponic culture of JS-335 and Bragg cultivars of soybean (Glycine max) were raised to analyze changes in growth, reactive oxygen metabolism in terms of H2O2 content, lipid peroxidation (TBARS), free radical quenching systems (nonenzymatic and enzymatic antioxidants) and ion accumulation in different plant parts under NaCl and CaCl2 stress. Fifteen-day-old seedlings were treated with solutions of 25 mM (T1 ), 50 mM (T2 ) and 100 mM (T3 ) NaCl alone and in combination of 10 mM CaCl2 i.e., 25 mM + 10 mM (T4 ), 50 mM + 10 mM (T5 ) and 100 mM + 10 mM (T6 ). Observations recorded at 30 days after sowing displayed significant decreases in plant biomass, leaf water potential, leaf area, chlorophyll content and the contents of glutathione (GSH) and ascorbate (AsC) on application of NaCl alone. However, H2O2 content and lipid peroxidation (TBARS) in leaves were enhanced, consequently invoking the activities of SOD, APX, GR and CAT. Application of NaCl + CaCl2 alleviated adverse effects of NaCl stress. The Na+ and Cl- contents in different plant parts increased with NaCl as well as with NaCl + CaCl2 treatments. The maximum accumulation occurred in roots, followed by the stem and the leaves. The K+ and Ca2+ contents decreased under NaCl stress; but NaCl + CaCl2 treatment reduced the extent of decrease caused by NaCl. Thus, calcium ameliorated the deleterious effects of NaCl stress and stimulated plant metabolism and growth.