Abstract:Using ordinary japonica rice as control, seven super japonica rice cultivars from the middle and lower areas of the Yangtze River were selected to investigate the effects of different nitrogen application levels (0, 150.0, 187.5, 225.0, 262.5, 300.0, 337.5 kg/ha) on their yield formation and the characters of nitrogen utilization under field conditions. Results showed that the highest yield is obtained with super japonica rice at nitrogen application level of 300.0 kg/ha and ordinary japonica rice at 262.5 kg/ha. The highest average grain yields of the seven super japonica rice cultivars was 8.5% higher than that of the ordinary japonica rice. Compared with ordinary japonica rice, the number of stems and tillers of super japonica rice are stable with higher percentage of productive tillers. The leaf area index and photosynthetic potential of super japonica rice was relatively low before jointing stage, and increased significantly after jointing stage. The dry matter and nitrogen accumulations in super japonica rice are similar to that of ordinary japonica rice before jointing, but 7.31% and 6.55% higher at jointing-heading stage, 8.98% and 9.66% higher at heading-maturity stage, respectively. The nitrogen use efficiency in super japonica rice is 3.73%, 11.63% and 7.95% higher than the ordinary japonica rice, respectively, suggesting that super japonica rice is adapted to high nitrogen fertilizer rate, and has relatively high nitrogen use efficiency under high fertility condition.