Abstract:In order to explore the difference of growth and element accumulation of Populus davidiana seedlings under the combined of compound treatment of cadmium (Cd) and exogenous nitrogen (N), we studied the effects of N on morphology, chlorophyll, starch and soluble sugar contents, total nitrogen (N), total phosphorus (P), total potassium (K) and Cd content in leaves under Cd stress by pot experiment. The results showed that: (1) the leaf width and stem diameter of P. davidiana were significantly inhibited by Cd alone. The toxicity of Cd to plants was compensated by exogenous N under Cd stress, and the leaf length, leaf width and stem diameter were significantly increased compared with Cd treatment alone. (2) Compared with the control, the chlorophyll content and starch content of P. davidiana leaves decreased significantly after Cd treatment, while the soluble sugar content increased significantly. Compared with Cd+N treatment, the chlorophyll content increased significantly, the starch content decreased significantly, and the soluble sugar content decreased slightly. (3) Compared with the control, the total N content and total P content of P. davidiana leaves decreased significantly after Cd treatment. The total N content increased significantly and the total P content decreased significantly after N treatment and Cd+N combination treatment. However, there was no significant difference in total K content among all treatments. (4) Under Cd stress, the Cd content in leaves of P. davidiana seedlings was significantly increased compared with the control, and the Cd content in leaves of Cd+N composite treatment was about twice as much as that of single Cd treatment. The results showed that the adaptability of P. davidiana seedlings and Cd accumulation ability of leaves could be improved by increasing N application under Cd stress.