Abstract: The field experiment was conducted in 2006 to research the difference of characteristics of dry matter accumulation and nitrogen uptake and utilization between five super rice cultivars and the control—Shanyou 63. The dry matter production of middle-season indica super hybrid rice was started from the beginning of elongation stage, and with the rice growing, the comparative advantage of dry matter accumulation was gradually speeded up. The middle-season indica super hybrid rice had apparent advantage in biomass accumulation after heading. Total amount of nitrogen absorption was 196.5 (184.3–200.8) kg ha^-1 in super rice cultivar, which was 20.0 kg ha^-1 higher than that of control. The amount of nitrogen absorption of middle-season indica super hybrid rice cultivar corresponded to that of control before jointing stage, however, increased 9.2 kg ha^-1 more than that of CK from jointing stage to heading stage, 4.9 kg ha^-1 more than that of CK at 25 days after heading stage, and 4.3 kg ha^-1 more than that of CK from 25 days after heading stage to maturity. The Nitrogen uptake rate reached its peak at booting stage, and the middle-season indica super hybrid rice was 3.68 (3.44–3.96) kg N ha^-1 d^-1 while the control was 3.55 kg N ha^-1 d^-1. And then, the nitrogen uptake was slower and slower after booting stage, and at 25 days after heading and at maturing stage, the N-uptake rate was 0.36 kg N ha^-1 d^-1 in super rice, whereas it was almost zero in the control. It can be seen that middle-season indica super hybrid rice held high N rate in the leaf blade after heading stage, which was beneficial to chlorophyll contents stability and photosynthate accumulation so that the super high yield of the rice could become true. The result also showed that the super hybrid rice should absorb about 1.83 kg N per hundred kilogram grain when its yielding level was 10.5 t ha^-1.

Key words: Middle-season indica super hybrid rice, Nitrogen, Absorption/translocation, Dry matter production