Effects of copper on growth, accumulation, antioxidant activity and malondialdehyde content in young seedlings of the mangrove species Kandelia candel (L.)

The effects of different concentrations of copper (Cu) on the growth, Cu accumulation, antioxidant enzyme activity and malondialdehyde (MDA) content of seedlings of the mangrove species Kandelia candel L. were investigated. Seedlings were treated with several concentrations of CuCl2 (0, 1, 5, 10, 20, 30 or 40 mg L-1) for 3 months. The results indicated that a high dose of Cu significantly decreased the growth of K. candel in terms of seedling height, leaf number and total biomass. At the highest Cu concentration (40 mg L-1), there was a 39.53% decrease in final seedling height, a 53.25% decrease in leaf number and a 35.96% decrease in total biomass. Cu ions were accumulated mainly in the roots (96%), and only small amounts were translocated to the hypocotyl, leaves and stem. The MDA content increased with increasing external Cu concentration both in roots and leaves. A significantly higher superoxide dismutase, peroxidase and catalase antioxidative enzyme activity occurred in roots and leaves of plants exposed to 20 mg L-1 CuCl2 compared to other treatments, suggesting that K. candel seedlings can tolerate up to 20 mg L-1 Cu treatment.