Effects of different fertilization on nitrogen uptake, net photosynthesis rate and yield of rice

The effects of different fertilization on nitrogen uptake, net photosynthesis rate and yield of rice were studied in a long-term positioned fertilization experimental field. The results show that the number of tillers, panicles per unit area, LAI, and grain yield of rice are obviously increased under the organic materials returning fertilization. Under the NPK fertilization, the content of nitrogen in leaves is declined sharply after the tillering stage of early rice, while the earing fertilization of late rice could increase the nitrogen uptake in the late period. Organic materials returning fertilization could improve nitrogen uptake in the mid-late period. But the effect on early rice is obviously better than that on late rice. The contents of nitrogen in leaves and grains of early rice are higher than those of late rice. There is a significantly positive correlation between net photosynthetic rate and content of nitrogen in leaves (early rice, r=0.664; late rice r=0.704*), which indicates that the lack of nitrogen in leaves could decrease the net photosynthetic capacity. Organic materials returning fertilization could significantly improve the yield of rice. At middle level of fertilizing, organic materials returning fertilization could reduce more than 1/3 of NPK using.