Abstract: The poplar is a main tree species of the farm shelterbelt in Northeast China. This farm shelterbelt with single tree species is easily caused plant diseases and insect pests . The mixed plantation usually result in restricting normal growth of some trees owing to different growth speed. The object of the experiment is poplar and elm mixed shelterbelt. Three mixed patterns and three dosage of nitrogenous fertilization were selected in the mediating growth experiment. The results showed that fitable afforestation pattern of poplar and elm mixed shelternet and rational nitrogenous fertilization dose could enhance elm growth, that was restricted because of the slow growth of young trees.The study provided the guide for the rational afforestation and management of poplar and elm mixed plantation.

Key words: wheat, low temperature stress, photosynthetic performance, chlorophyll fluorescence.