Abstract

The influence of salicylic acid (SA), sodium nitroprusside (SNP) and their reciprocal effects (SA+SNP) on certain physiological parameters in soybean seedlings grown in saline and non-saline conditions was investigated. The changes of leaf area, shoot fresh, dry weights and content of photosynthetic pigments showed that the addition of 100 µM SA and/or 100 µM SNP markedly declined the oxidative damage to soybean plants treated with NaCl salinity. The results proved that the interaction of salicylic acid with nitric oxide donor significantly enhanced the activities of catalase (CAT), ascorbate peroxidase (APOX) and guaiacol peroxidase (GPOX). Also, they decreased the amounts of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) in soybean leaves under sodium chloride toxicity. In order to reduce the oxidative damage caused by NaCl stress, the protective role of SA+SNP was often better than that of SA and SNP alone. As well, it was observed that the accumulation of proline was apparently accelerated by these substances under salt stress and that the interaction of salicylic acid with nitric oxide has synergistic effects in decreasing the deleterious effects induced by NaCl salinity.

Key words: Salicylic acid, nitric oxide, NaCl salinity, soybean.