Responses of Distylium chinense to Cd Stress in Cd Accumulation, Growth and Chlorophyll Fluorescence Dynamics

Distylium chinense (growth similar), a dominant species in the Three Gorges Reservoir area, is selected as object for the study to investigate responses of the tree to Cd stressw(Cd²⁺), 0, 2, 5, 15 and 30 mg·kg^-1 in Cd accumulation, growth and chlorophyll fluorescence parameters. Results show that Cd stress, moderate and high in concentration, inhibited significantly growth in height and total chlorophyll content of the plant under stress. Chlorophyll fluorescence parameters of the plant can be used to explain Cd tolerance of the plant physiologically. Cd stress damaged the plant's photoreactive center PSⅡ, though reversibly. Chlorophyll fluorescence parameters (F_v/F_m and R_ET) declined first and gradually came back with the stress going on. Under the Cd stress of 2 mg·kg^-1, Cd enrichment coefficient of the plant reached up to 7.4, 8.1 and 8.2 in roots, stems and leaves, respectively, and Cd transfer coefficient up to 1.01 and 0.94 in stem and leaves, respectively. Obviously Distylium chinense possesses a high Cd accumulation and transfer capacity. According to the pollution status of the Three Gorges Reservoir area, Distylium chinense can be used as a potential species for phytoremediation of Cd contaminated soils.