Effects of Different Cadmium Stress on Growth and Physiological Characteristics of Hedera helix

Taking Hedera helix cutting seedlings of the year as the research object, the CdCl₂ solution was used for stress treatment. The effects of different concentrations of cadmium stress on growth morphology and antioxidant enzyme system were studied. Results show that under Cd²⁺ stress treatment of 20 μmol/L and 80 μmol/L, the growth and biomass accumulation of H. helix are less affected. there is no significant elongation of shoots and internode of H. helix. and the difference in superoxide anion and malondialdehyde content was not significant. However, catalase and peroxidase activities are 5 and 6 times higher than the control under 80 μmol/L Cd²⁺ stress, respectively. Under the stress of 400 μmol/L Cd²⁺, the plant height, internode length, leaf number and leaf biomass are significantly lower than the control, while the content of superoxide anion and malondialdehyde increased by 72.3% and 56.2%, respectively. Soluble protein, proline content, ascorbate peroxidase and peroxidase activities increase significantly, about 2 times, 6 times, 2 times and 14.7 times higher than the control, respectively. It indicates that the accumulation of osmotic adjustment substances and the increase of antioxidant enzyme activity at this time are not enough to alleviate the peroxidation damage caused by high Cd²⁺ stress. It can be seen that H. helix can resist lower concentrations of Cd²⁺ stress by regulating partial osmotic substances such as soluble protein, proline content, and regulating catalase and peroxidase activities in antioxidant enzyme systems.