Abstract: 【Objective】 The characteristics of dry matter and photosynthetic production of different rice varieties under their best-fit nitrogen levels were studied. 【Method】 The field experiment was carried out with 50 early-maturing late Japonica rice varieties, adopted in the region of Yangtze River, under seven nitrogen levels (0, 150.0, 187.5, 225.0, 262.5, 300.0, 337.5 kg•hm-2) to investigate the difference of dry matter accumulation. The highest value of dry matter accumulation under different nitrogen levels was defined as the most productivity of N fertilizer group (MPNG). Then according to MPNG, rice varieties could be classified into four types including low type, middle type, high type and top type. On this basis, the dry matter accumulation, LAI, photosynthetic potential, crop growth rate and net assimilation rate of the four types rice varieties were studied. 【Result】 The main results were as follows: In the range of 0-337.5 kg•hm-2 nitrogen application, the dry matter accumulation at jointing and heading of 50 rice varieties were significantly increased, while the dry matter accumulation at maturity increased firstly and reduced afterward with the  nitrogen application increasing. Population dry matter accumulation at jointing stage decreased as the productivity level increasing, for the dry matter accumulation of top and high levels were increasing much greater than middle and low levels after jointing, there was a little difference among the 4 productivity levels at heading stage. The dry matter accumulation of top productivity level was significantly higher than the other three productivity level varieties at maturity. There was a significant negative correlation between dry matter accumulation and MPNG at early growth stages, while there was a significant positive correlation between them at the middle and later stages of rice growth. The dry matter accumulation at sowing-jointing stage decreased as the productivity level increasing, while it was increased at jointing-heading and heading-maturity stage. The ratio at each stage changed accordantly with the dry matter accumulation. The economic coefficient of different productivity level varieties significantly increased as the productivity level increasing. Before jointing, the differences of leaf area index and photosynthetic potential of 4 productivity level varieties were tiny, while the population growth rate and the net assimilation rate had a significant degressive tendency; at Jointing-heading and heading-maturity stage, leaf area index, photosynthetic potential, the population growth rate and the net assimilation rate were all increased as productivity level increasing. 【Conclusion】 The dry matter production of top level varieties at heading-maturity stage have obvious advantages, they have high leaf area index, photosynthetic potential, population growth rate and net assimilation rate. 

Key words: rice, productivity, nitrogen, drymatteraccumulation, photosyntheticproduction