Effect of nitrogen application amount and stage management on nitrogen content in plant and grain yield of super hybrid rice
施氮量和时期运筹对超级杂交稻植株氮含量与籽粒产量的影响研究

Two field experiments, i.e., nitrogen-fertilizer amount and ratio in different growth stages, were conducted by using current representative super hybrid rice--No1 Y Liangyou at the middle and down reach of Yangtze River. The dynamics of stem-leaf nitrogen content affected by nitrogen-fertilizer amount and fertilization stage, relationship between nitrogen application and plant nitrogen content, plant nitrogen content and grain yield were studied to understand the amount and ratio of spike nitrogen. The results showed that the nitrogen content in stem-leaf over the whole growth season, especially in generative growth stage were linearly raised as nitrogen-fertilizer amount increased; Compared with total nitrogen amount, the coefficients of spike nitrogen amount and stem-leaf nitrogen content in generative growth stage were 1.88, 1.02, 1.86 and 2.28 times higher respectively, the coefficient of spike nitrogen amount and grain nitrogen content in mature stage was 3.59 times higher. The nitrogen content in stem-leaf from active tillering stage to heading stage was significantly positive linear correlated with grain yield, but the nitrogen content in stem-leaf and grain at mature stage was secondary parabola correlated with grain yield; The spike nitrogen amount of the highest yield was 59.0 kg/hm2, accounted for 32.8% of total nitrogen application, which was figured out through simulated models and oblanceolate of leaf in different nitrogen fertilization treatment observed during experiment. The rational nitrogen ratio at the four stage, which distributed part of spike nitrogen (15%) to grain was more beneficial to high yield of super hybrid rice. Their yields were near to the highest yield which was measured from equation. The rational spike (and grain) nitrogen ratio is propitious optimize nitrogen content in stem-leaf of super hybrid rice at manure stage subsequently to build the highest storage capacity and realize the maximal yield level of super hybrid rice.