Abstract: The nutrition characters, leaf colour of 3 rice varieties and their nitrogen fertilization techniques were studied in the area along the Yellow river. The results indicated that the amount of N, P and K absorbed by the tried varieties of rice was different during the period of growth. The absolute absorption amount of N, P and K was the most for Zhengdao 6, and the least for Huangjinqing. The N accumulation amount of Zhengdao 6 was less at the early middle stage and more from earing stage to mature stage, compared to the other tried varieties. Therefore, the nutrition characters of rice should be considered when applying nitrogen for ensuring the high yield of rice and high nitrogen efficiency. There was closely relationship between the second-top leaf color of rice and the application rate of nitrogen fertilizer. The SPAD value changed from 41.8 to 22.1 as the low amount of nitrogen fertilizer (112.5 kg/ha)was used, and it changed from 44.3 to 26.4 in the middle amount of N(225.0 kg/ha)application and from 44.1 to 32.3 in the high amount of N (450.0 kg/ha)application. The SPAD value of rice second-top leaf could maintain 37 and above before the ear-filling stage, especially the leaves maintained green and not too rich at the later stage when the middle amount of N (225.0 kg/ha)was applicated. So, 37, the SPAD value of the second-top leaf before the ear-filling stage could be a reference index of the nitrogen fertilizer application.

Key words: The area along the Yellow River, Nutrition character, Leaf color