Abstract: Chinese Journal of Ecology,1993,12(6)：34-36.In This paper,a regression wodel on nitrate accumulation in spirach is establised,which can predict the accumulation amount of nitrate under different application rates of N,P and K fertilizers.Using this model,the nitrate content in spirach can be controlled through fertilization,and its harmful effect on baman body can be reduced.

Key words: winter wheat, planting density, root system, spatiotemporal distribution, nitrogen use efficiency.