Abstract:In order to investigate the effect of nitrogen application on super rice yield, photosynthetic characteristics and recovery efficiency of nitrogen fertilizer. A pot-cultured experiment with hybrid rice, Liangyoupeijiu,and inbred rice, Yliangyou1hao,Yuxiangyouzhan and Huanghuazhan was conducted by using15N isotope tracing. The results revealed that SPAD value and photosynthetic rate increased with the increase of nitrogen rate, of which varieties was consistent. After the jointing stage, SPAD values appeared as the changing trend of the high-low-high, changing trend of photosynthetic rate was different between varieties, of which hybrid rice linearly decreased and inbred rice showed firstly linear decline and then slightly rebounded. With the increase of nitrogen application rate, content of nitrogen in the straw of hybrid rice was lower than that of inbred rice, of which they were 0.72%~0.78% and 0.59%~0.61%, respectively; but no differences between hybrid rice and inbred rice were found in the grains. Meanwhile, the grain yield was performed the increase stability and the recovery efficiency of nitrogen fertilizer were performed nonlinear change trend. The recovery efficiency of nitrogen fertilizer with 150 kg·hm-2 treatment were the highest among all treatments, hybrid rice was 33.9% to 34.6% and inbred rice was 33.8% to 34.2%. And the yield of hybrid rice is significantly 16.4% higher than that of inbred rice. It is concluded that, with the increase of nitrogen rate, hybrid rice could transfer the nitrogen from the straw into the grains through photosynthesis, while the inbred rice accumulate the nutrient in the straw. The findings could provide the cultivation theoretical basis of the coordination of nitrogen efficient and hybrid high-yield.