Abstract: The differences of organic nitrogen redistribution in vegetative of oilseed rape varieties with different nitrogen physiological efficiency during the later growing period were studied using 15N trace method under the sand culture of complete nutrient solution condition,. Results showed that high nitrogen physiological varieties had larger amount of organic nitrogen redistribution compared with the low nitrogen physiological efficiency varieties. The speed of organic nitrogen redistribution was slow at first and then fast, the redistribution amount of nitrogen toward seeds and its proportion was larger, the redistribution amount of nitrogen toward weed shell and its proportion was smaller. The amounts of nitrogen loss from plant and its proportion were smaller, and the velocity of nitrogen loss is slower. This may be one of the main reasons why the varieties with high nitrogen efficiency have high nitrogen harvest indexes. By comparing the redistribution amount of nitrogen and its proportion during the four growing periods, the results showed that the largest redistribution amount of nitrogen absorbed by plant and its proportion was found in flower bud stage, the smallest redistribution amount and its proportion at siliquing stage, and those were between them at seeding and flowing stages.

Key words: Oil-seed Rape, Nitrogen Reuse, Nitrogen Loss from Plant