Abstract:A field experiment was carried out to investigate the effects of nitrogen fertilization rates on grain yield and processing quality. Strong gluten wheat cultivars, Jimai 20 and Wanmai38, and middle gluten wheat cultivars, Jingdong 8 and Zhongmai 8 were selected as test materials. The results show that within the range of 0~360 kg/ha fertilizer levels, the increase of the amount of N-fertilizer could suppress chlorophyll’s degrading, keep the N-content of flag at a high level, ease flag leaf senescence, and prolong the functional stage of flag. The chlorophyll and N contents of flag leaves of the strong gluten wheat cultivars are decreased slowly than those of the middle gluten wheat cultivars. The grain yields and protein contents are all increased with the increase of the N-fertilizer amounts, and reach their maxima under the treatment of applying nitrogen at N 270 kg/ha. When the nitrogen application rate reaches to 360kg/ha, the grain yields and protein contents are decreased. The grain yields and protein contents of the strong gluten wheat cultivars are higher than those of the middle gluten wheat cultivars, while the spike numbers, grains per spike more and grain weight of the middle gluten wheat cultivars are higher. The nitrogen fertilization could increase flour yield, rigidity, protein content and sedimentation volume. The nitrogen treatment of 180kg/ha can prolong the development time and stability time and decrease the water absorption, and the score of bread is highest. The hardness, protein content, flour yield and sedimentation value of strong gluten wheat are high, the dough development time and stability are long, and the bread bulky and score are high.