In this paper,two oilseed rape varieties named X-13 and X-29 were used as plant materials for sand culture with the different nitrogen (N) application levels to study the different effects of N application levels on accumulation amount of nitrate,nitrate reductase (NR) activity,absorption amount of N,seed yield and N efficiency in the two oilseed rape varieties.The results showed that compared with X-29,the nitrate N accumulation is higher,reutilization ratio of nitrate,the activity of NR in leaf,N accumulation,amount and seed yield are inc...