Effect Of Nitrogen Management On Absorption And Utilization Of Nitrogen And Yield Of Super Hybrid Rice

The experiment of different N application rate (Experiment 1,2008), N application ratio at different rice growth stage (Experiment 2,2008), and N, P and K combined application (Experiment 3,2009) were carried out at super rice tackling area of Liuyang Yongan, Hunan Province using super rice Y liangyou No 1 as experimental material. And the change of ammonium nitrogen (NH4+-N) content in soil, carbon and nitrogen accumulation of plant, the biomass, the yield and its components, and so on, were studied systematically. The main results were showed as follows:1. In a certain range of N-fertilizer amount, the biomass of super rice in differernt growth period and the yield increased as N-fertilizer amount increasing. With progress of rice growth, the effect of N-fertilizer on biomass increasing was becoming obvious. The contribution of total grain number per spike to yield was the most of all the yield components, so, it was key to construct super rice's storage capacity which the total grain number was the key to reach high yield. When the ratio of base fertilizer and panicle fertilizer was adjueted to 60:40 and nitrogen fertilizer was further distributed to base fertilizer:tillering fertilizer:panicle fertilizer:granular fertilizer as 10:50: 25:15, total grain number per spike,filled grain number and yield increased significantly. This experiment showed that reasonable retroposition of N-fertilizer or reasonable distribution of N-fertilizer in different growth period could increase some yield components including total grain number per spike and filled grain number and so on, thus increased the storage capacity of super rice.2. With progress of rice growth, carbon and nitrogen content in plant was being decreased, the ratio of carbon and nitrogen was being increased continuously. The decreasing rate of plant nitrogen content of super hybrid rice with growth was decreased as N-fertilizer amount increasing. The ratio of carbon and nitrogen of super hybrid rice in middle-latter growth period decreased with N-fertilizer amount increasing. The ratio of carbon and nitrogen of super hybrid rice was correlated with yield negatively. The yield of super hybrid rice was showed quadratic relationships with total nitrogen accumulation amount of super rice.3. Basic fertilizer provided nitrogen nutrient for super hybrid rice by 0～10cm soil layer. Increasing NH4+-N content in 5-20cm soil layer in middle-latter growth period of super hybrid rice was good for nitrogen nutrient uptaken by super hybrid rice plant. The SPAD value of parietal lobe of super hybrid rice appeared only one peak at early tillering stage in no fertilization treatment(CK), but the SPAD value of parietal lobe appeared two peaks at early tillering stage and early heading stage separately in the other experiment treament. Increasing N-fertilizer amount and reasonable N-fertilizer distribution could boost the absorption of nitrogen nutrient of super hybrid rice.4. The reasonable combined application of N-fertilizer,P-fertilizer and K-fertilizer could increase yield of super hybrid rice obviously. K-fertilizer was better for maintaining high soil NH4+-N and NO3--N content than P-fertilizer, thus benefit for the absorption of nitrogen nutrient of super hybrid rice. The efficiency of K-fertilizer on the yield was exceeded that of P fertilizer, but excessive K-fertilizer application rate lead to reduction of yield due to antagonism of K to middle elements or trace elements in soil. The mechanism of antagonism of K to absorption of middle elements or trace elements of super rice should be further studied.