Effect of salicylic acid on salinity-induced changes in Brassica juncea

Seeds of Indian mustard (Brassica juncea (L.) Czern. et Coss.) were exposed to 0, 50, 100 and 150 mmol/L NaCl for 8 h and seeds were sown in an earthen pot. These stressed seedlings were subsequently sprayed with 10 mu mol/L salicylic acid (SA) at 30 d and were sampled at 60 d to assess the changes in growth, photosynthesis and antioxidant enzymes. The seedlings raised from the seeds treated with NaCl had significantly reduced growth and the activities of carbonic anhydrase, nitrate reductase and photosynthesis, and the decrease was proportional to the increase in NaCl concentration. However, the antioxidant enzymes (catalase, peroxidase and superoxide dismutase) and proline content was enhanced in response to NaCl and/or SA treatment, where their interaction had an additive effect. Moreover, the toxic effects generated by the lower concentration of NaCl (50 mmol/L) were completely overcome by the application of SA. It was, therefore, concluded that SA ameliorated the stress generated by NaCl through the alleviated antioxidant system.