Activity of antioxidative enzymes in watercress and Chinese cabbage plants grown under hydroponic system with brackish water

Abstract

Underground water reserves in Semiarid Region present high salinity levels; however, scarcity of resource compels farmers to use this water for conventional agriculture. Biomass production and activity of the antioxidative defense system of Chinese cabbage and watercress were evaluated in plants grown under hydroponic NFT system with brackish water. The experimental design was completely randomized, with four replications and five water salinity levels (1.95; 3.37; 4.48; 6.82 and 7.51 dS m-1), obtained by an increasing addition of NaCl into the local water supply and nutrient salts for preparation of nutrient solution. Both watercress and Chinese cabbage plants decreased in fresh and dry shoot biomass, in relation to increase of salinity in solution, considering that these losses were marked in Chinese cabbage crop. The antioxidative defense system was activated in both evaluated species. Superoxide dismutase (SOD) and peroxidase (POD) increased their activity in relation to salinity increase in the solution. Watercress presented higher POD activity and was able to maintain catalase (CAT) and total phenols higher than control in most treatments, resulting in better adaptation to salt stress.