Effect of Cu and Pb pollution on the growth and antionxidant enzyme activity of Suaeda heteroptera

This paper studied the impact of Cu and Pb pollution on concentrations of reactive oxygen species (superoxide anion radical (O2●−) and peroxide (H2O2)) and on the activity of antioxidant enzyme (superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD)) in the halophyte Suaeda heteroptera. At concentrations less than 50 mg kg−1, Cu had little effect on S. heteroptera. At concentrations higher than 200 Cu mg kg−1, the growth of S. heteroptera was significantly inhibited, an impact that was most pronounced in seedling weight (p < 0.05). At concentrations of Pb higher than 400 mg kg−1, the growth of S. heteroptera was also significantly affected (p < 0.05). Antioxidant enzyme activities in S. heteroptera increased and then decreased with increasing Cu concentrations, while reactive oxygen species concentrations continually increased. SOD decreased significantly with Pb pollution (p < 0.05), while the concentrations of reactive oxygen species rose slowly. The combined effect of Cu and Pb contamination on the growth and antioxidant enzyme activities of S. heteroptera was higher than with single Cu. With the increasing concentration of Cu, this synergistic effect enhanced (p < 0.05), indicating that S. heteroptera is more sensitive to Cu than to Pb. Besides, the growth index of S. heteroptera was significantly inhibited with the increasing concentration of single and combined Cu and Pb exposure.