Differences of N efficiency of oilseed rape(Brassica napus L.)varieties and their physiological properties were studied using a pot experiment and the ratio of seed yield with stressed nitrogen to that with normal N supply was adopted as nitrogen efficiency coefficient.Results showed that the determined nitrogen efficiency coefficient of 8 oilseed rape varieties varied from 0.37 to 0.69

the ratio of nitrogen uptake amounts per plant

nitrogen transfer velocity from stems and leaves to seeds

and nitrogen physiological efficiency of oilseed rape varieties under N stressed condition to that with normal N supply were different.The higher the nitrogen efficiency

the higher their ratio.Under low nitrogen-supplying condition

high nitrogen efficiency varieties had longer roots

more lateral roots

higher nitrate reuse amounts of stem and leaves and nitrate reductase activities in leaves.