Exogenous application of salt (NaCl) inhibit antioxidative system in Cd-treated watercress (Nasturtium officinale R. Br.)

This research simulates conditions found in metal-contaminated sites also affected by a high concentration of salt. For these reasons, several exogenous doses of NaCl were used to treat Cd-stressed Nasturtium officinale R. Br. We have chosen Nasturtium officinale R. Br which is a hyper accumulator plant of metals (based on literature). Data suggested induction of oxidative stress under Cd treatment and demonstrated watercress's capacity to upregulate its antioxidative defense. Superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and peroxidase (GPX) activities were stimulated by Cd. Supplementation of (100, 200, 300 mM NaCl) simultaneously with 1 MCd to six weeks aged Nasturtium officinale R. Br caused growth inhibition, reduction of photosynthetic pigment contents and a significant increase of Malonyldialdehyde (MDA) and hydrogen peroxide (H2O2) ones in leaves. Increase of NaCl dose reduced Cd tenor in Nasturtium officinale leaves. Moreover, a dramatic lost of antioxidant system efficiency was detected in these plants. Rise of salinity concentration significantly inhibited SOD, CAT, APX and GPX activities in Cd-treated Nasturtium officinale R. Br.