Mitigation of salt-induced oxidative damage in Chinese kale (Brassica alboglabra L.) using ascorbic acid

Salinity could become a threat to hydroponically grown plants due to the differential ion uptake process by the crop itself and/or using low quality irrigation water containing non-essential ions such as sodium and chloride. This study was conducted to determine the interactive effects of salinity and foliar application of ascorbic acid (AsA) on the survival capacity of Chinese kale plants. Three-week-old plants at the 4-leaf stage were exposed to salinity by application of 0, 50 and 100 mM NaCl for 14 days. The activities of antioxidant enzymes, catalase (CAT), peroxidase (POX) and ascorbate peroxidase (APX) along with changes in the accumulation of proline, lipid peroxidation and chlorophyll content in leaves were estimated. Salinity induced obvious changes in the activities of antioxidant enzymes, lipid peroxidation, proline accumulation and chlorophyll content in the leaf tissues. Exogenous application of AsA (5 and 10 mM) to stressed plants resulted in a significant increase (P < 0.05) in APX activity and reduction in the activities of antioxidant enzymes (CAT and POX) as well as a decrease in the contents of stress-induced proline and malondialdehyde (MDA). Higher chlorophyll content was also recorded in stressed plants using AsA. The inherent capability of AsA to scavenge free radicals may have assisted the plant using the lower oxidative damages. The results of this study showed that AsA treatment would reduce the deleterious effects of salt-induced oxidative stress and improve plant tolerance to salt stress.