Abstract: The effects of amount of nitrogen and planting density on N absorption and yield formation of rice were studied with mid season rice japonica cv. 9516 and indica hybrid rice Shanyou 63. The results are as follows: at maturing stage, the total amount of N absorption (ANA) in plants and in panicles were increased with the increase of N application, but the ratio of ANA of panicles to the total ANA of plants decreased, the total ANA varied among different row spacings. Diversification of the total number of spikelets per area,ANA per plant varied in large range, but the relative capacity of producing spikelet per N application varied in little range. At heading stage, amount of N application in rice can be exactly calculated, according to the numbers of spikelets of anticipated yield and the number of spikelets produced per ANA at different base soil fertility. Caculating the comparative ANA divided by the utilization efficiency of N at heading stage, which can provide theoretical basis for quantitative fertilization in production.

Key words: rice, nitrogen, fertilizer application rate, cultivation method, yield

摘要： 以迟熟中粳稻9516和杂交中籼稻汕优63为材料，研究不同栽插密度（行距）和施氮量对水稻氮素吸收、产量形成的影响。结果表明，成熟期植株总吸氮量和穗部吸氮量随施氮量的增加而增加，但穗部吸氮量占总吸氮量的比例呈下降趋势，栽插行距不同总吸氮量有差异。不同处理抽穗期群体总颖花量、植株吸氮量变化幅度较大，抽穗期单位氮素相对产颖花能力变化幅度较小，因而可以根据预期产量指标的颖花量和不同地力单位氮素相对产颖花能力，计算得出抽穗期相对吸氮量，并除以抽穗期氮肥利用效率，就可较确切地算出水稻的施氮量，为生产上定量施肥提供理论依据。

关键词: 水稻, 氮素, 施肥量, 栽插方法, 产量