Physiological characteristics and Cd absorption and transportation in Salix integra under Cd stress

To evaluate the potential for Cd-polluted soil remediation by Salix integra under Cd stress, plant growth, physiological characteristics, Cd absorption, and transportation characteristics were observed. S. integra seedlings were employed as experiment materials; plant growth, root configuration, physiological responses of roots and leaves, and Cd absorption and transportation were investigated under different Cd stress concentrations (0, 10, 20, 30, 40 mg·L⁻¹) using hydroponic equipment. The results showed that S. integra has good Cd tolerance, and the absorbed Cd is mainly concentrated in the shoot, and is highest in leaves and lowest in the stem. The transport coefficient increases while the enrichment coefficient gradually decreases with the increase in Cd concentration. Cd stress had a stimulating effect on root architecture, and the number of nodes and root tips increased significantly (P < 0.05). In addition, a low level of Cd (10 mg·L⁻¹) stress enhanced the biomass and total root length, and a high level of Cd (40 mg·L⁻¹) stress decreased root biomass. At the same time, the superoxide anion activity unit and CAT activity in roots and leaves were induced by Cd stress, but GSH content and GR activity were significantly decreased with increasing Cd concentration (P < 0.05). In conclusion, S. integra has good tolerance and enrichment characteristics for Cd stress, and has high Cd pollution remediation potential by promoting root growth and activating the antioxidant enzyme system.