Abstract:In order to reveal the effects of single and combined treatment with different concentrations (0, 2, 4, 8, 16 mg·L-1) of hydroxylated multi walled carbon nanotubes and 10 μmol·L-1 Cd, we studied root growth physiological indexes and Cd content of Vicia faba seedlings by hydroponic method. The results showed that: (1) with the treatment of single MWCNTsOH, with the increase of MWCNTsOH concentration (2-8 mg·L-1), the length of V. faba root increased, and the production rate of OO2-· increased along with the increase of SOD and POD activities. (2) The MDA content and O2-· production rate of seedlings treated with single Cd were both higher than that of the control group, and the O2-· production rate was 1.98 times higher than that of the control group. (3) The MWCNTsOH combined treatment induced the production of O2-· and the increase of MDA content in the root of V. faba seedlings. The 16 mg·L-1 MWCNTsOH combined with Cd caused the greatest damage to the root of V. faba seedlings, and some root tip cells were damaged and shed, and Cd content was significantly decreased. It was found that low concentration of MWCNTsOH could promote root length and reduce the toxicity of Cd, while high concentration (16 mg·L-1) of MWCNTsOH combined with Cd had a synergistic effect on root toxicity of V. faba seedlings.