Interactive Effects of Cd and Pb on the Photosynthesis Efficiency and Antioxidant Defense System of Capsicum annuum L

In this study, the interactive effect of Cd and Pb on the growth of Capsicum annuum L. was studied through pot experiments, and the indicators of photosynthesis efficiency (PE) and antioxidant defense system (ADS) were measured at different plant ages. Single Pb stress on PE and ADS was stronger than single Cd stress at the first month. Both the PE and ADS response showed a significant decrease under the combined stress of Cd and Pb, which was primarily dependent on the Pb concentration. With increasing plant age, the PE and response of non-enzymatic ADS exhibited dramatic decreases under Cd and/or Pb stress, and the activities of enzymatic ADS showed increases to some extent. The factorial analysis showed that Cd and Pb had an interactive effect to reduce PE, while slightly enhanced the activities of enzymatic ADS. Those results are useful to explore the interaction between Cd and Pb in the combined stress and understand their accumulation in the plants.