Effect of Copper Ion Stress on the Growth Characteristics and Physiological Parameters of Vallisneria Natans

The effects of Cu2+ on the growth characteristics and physiological indicators of Vallisneria natans were evaluated at five different concentrations (0, 1, 2, 4 and 6 mg.L-1, respectively). The results suggested that the stress effect of Cu2+ on Vallisneria natans was significant. The growth of Vallisneria natans was inhibited with shorted plant height and reduced fresh weight at the concentration of 2mg.L-1, but they can still survive. Inhibition became obvious at 4 mg.L-1, and after 30 days of stress, lateral blades of Vallisneria natans were decayed and blackened. Trace amount of Cu2+ promoted the activation of Catalase (CAT) activity and enhancement of plants stress resistance. In this research, the reaction between adverse situation and CAT was earlier than with MDA (malondialdehyde) and H2O2; therefore, it was more accurate and effective to monitor the changes in CAT content for physiological studies of Vallisneria natans in stress resistance. The growth of Vallisneria natans was inhibited when the concentration was 2mg.L-1. Therefore, it was not suitable to build submerged vegetation purification system of Vallisneria natans when the Cu2+ concentration was high in the polluted water.