| Increasing nitrogen uptake and utilization efficiency is an urgent issue of rice production with demands of high quality, efficiency, ecology and security. Efficient genotypes and reasonable nitrogen fertilizer management are effective measures to increase nitrogen uptake and utilization efficiency in rice. With 30 representative rice genotypes in south rice zone as experimental materials, this dissertation systematically studied genotypic differences in nitrogen uptake and utilization efficiency and effects of nitrogen fertilizer management and efficient silicon fertilizer on nitrogen uptake and utilization efficiency in rice, clarified improving their potential, physiological mechanism and regulation approaches for enhancing nitrogen efficiency.There were significant or highly significant differences in total nitrogen accumulation (TNA), nitrogen dry matter and grain production efficiency (NDMPE & NGPE), nitrogen agronomic efficiency (NAE), nitrogen transportation efficiency (NTE), nitrogen harvest index (NHI) and nitrogen recovery efficiency (NRE) among rice genotypes. This indicated great potential for improving nitrogen uptake and utilization efficiency in rice. Different types of rice showed different nitrogen uptake and utilization efficiencies. Genotypes with long growth duration exhibited high TNA, NDMPE, NGPE and NAE, and high NDMPE, NGPE, NAE, NRE and NHI for hybrid rice. It was discovered that ranking of identical genotype varied markedly among different parameters and for the same parameter in early and late season rice. Therefore, an integration ranking system with mean of seven parameters after standard transformation was brought forward and coincidence index was developed to evaluate the coincidence degree of integration ranking for genotypes at early and late season.Two parameters, nutrient balance index (NBI) and nutrient deviation index (NDI), which provided a way of quantitative expression of nutrient balance in rice plant, were put forward to evaluate balance of nitrogen, phosphorus, potassium and silicon accumulation in rice plant. Relationships between nitrogen accumulation and two parameters were analyzed. It was found that high accumulation of phosphorus, potassium and silicon increased TNA, high NBI increased NDMPE, and high NDI decreased NDMPE. However, NBI and NDI showed no significant correlation with TNA. These results indicated that nitrogenutilization efficiency was significantly influenced by nutrient balance, but nitrogen accumulation was not significantly influenced.The relationships between TNA and different form nitrogen accumulation and nitrogen accumulation in functional leaves (4 leaves from top) were established. Of various nitrogen forms, protein nitrogen was main form with the fraction of 74.27%~87.14% in total nitrogen. Nitrogen concentration and accumulation amount in rice plant had highly positive relationship with protein nitrogen concentration and accumulation. Of nonstructural nitrogen forms, free amino acid and chlorophyll content in leaf blade revealed close relationship with nitrogen content in plant and NDMPE. Yet carotenoid and nitrate nitrogen in leaf sheath showed no obvious relationship with nitrogen uptake and utilization. NDMPE was not only related to absolute nitrogen contents of various forms, but also related to their relative contents, that is, the ratios of various form nitrogen contents to total nitrogen content in plant. It was favorable for nitrogen utilization to have high relative content before heading and relative low content after heading of nonstructural nitrogen. Nitrogen accumulation in main functional leaves in rice had significant influence on plant TNA and NDMPE. Nitrogen accumulation in single leaf blade was positively related to TNA and negatively related to NDMPE. Ratios of nitrogen accumulation in functional leaves to plant nitrogen accumulation at panicle initiation, heading and filling stages showed significant or highly significant correlation to TNA and NDMPE. Also, the ratio of nitrogen accumulation in leaf b...
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