Abstract: The study was made about the effects of heavy application of N-fertilizer in the booting stage on the process of grain filling and the changes of dry matter production in the various organs of winter wheat plant in steady growth under no excessive N-fertilizer application .Results indicated:l.The application of N-fertilizer in booting stage can increase the weight of leaf per unit area, the strength of grain filling, 1000 grain weight and also extend the filling time.2. With the heavy N-fertilizer application in booting stage, vegetable organs e.g. the leaf, sheath and stem etc. Became strong, with the rate of grain filling speeded up. Because of this, the ability of lodging resistance, draught resistance and draught-heat resistance could be strenghthen. The dry matter weight of the vegetable organs per unit length or area was heavier under the treatment of N-fertilizer application in booting stage than in the heading stage except the control.3.There was no phenomenon of late maturing which is charac-teristie of reduction of 1000 grain weight with moderate application of N-fertilizer and steady growth of plants. It indicated that there was selective and limited absorption for N-fertilizer in late stage of wheat plants.It was concluded that the main cause for lodging and late maturing at the late growing stage was the extreme application of N-fertilizer and overgoing of N-metabolism in the early stage.

Key words: Winter wheat, Heavy application of N-fertilizer, The process of the grain filling