This study investigated the response mechanism of tung tree seedlings to chromium stress, in order to provide technical support for the application of tung trees in repairing soil environment polluted by chromium.

A pot experiment was carried out by using the one-year-old tung tree seedlings as the materials, to study the application of different concentrations of Cr (0, 50, 100, 200 and 500 mg·kg^-1 soil) on the photosynthesis, chlorophyll (Chl) content, peroxidase (POD), superoxide dismutase(SOD), malondialdehyde (MDA) content, relative conductivity, stomatal width, leaf structure and chromium content of tung trees.

1) The result indicated that when the soil Cr³⁺ concentration was 50 mg·kg^-1, the growth of tung tree seedlings showed no significant difference in comparison with the control; 2) With a soil Cr³⁺ concentration of 100 mg·kg^-1, the net photosynthetic rate(P_n), chlorophyll (Chl) content, and soluble protein content of leaves were significantly reduced (P < 0.05); 3) When the soil Cr³⁺ concentration exceeded 200 mg·kg^-1, the photosynthesis of tung tree seedlings was significantly decreased (P < 0.05), the contents of MDA and SOD increased, and the stomatal width and the thickness of leaves was significantly reduced (P < 0.05); 4) After long-term chromium stress (60 d) of 500 mg·kg^-1 Cr³⁺, the photosynthetic system of tung tree seedlings was severely damaged. P_n decreased by 89.02% compared with the control, and the total chlorophyll content decreased by 24.35%. The MDA content increased by 47.18%, resulting in membrane lipid peroxidation, the relative conductivity increased by 1.43%, and the blade thickness decreased by 26.71% (P < 0.05); 5) The content of Cr³⁺ in each part of the tung tree seedlings increased with the increase in the chromium concentration of soil. The accumulation of Cr in the roots of tung tree seedlings was the highest, and the accumulation of Cr in the roots of the tung tree seedlings in the 5 treatment groups were 61.51, 22.30, 61.77, 64.18 and 38.25 times that of the leaves, respectively.

Taken together, tung tree seedlings can absorb chromium in soil when the chromium concentration does not exceed 100 mg·kg^-1 in soil, playing a role in remediating heavy metal soil.