为了提高杂交水稻的施氮效率，2009-2016年以杂交中稻品种Ⅱ优7号、渝香优203、川香优9838、蓉18优1015为材料，在我国西南稻区的四川、重庆、云南、贵州4省（市）的7个生态点，采用相同的施氮量方案，研究了地理位置、土壤养分对稻谷地力产量的影响及其与高效施氮量和氮肥利用效率的关系。结果表明，稻田地力产量受土壤供肥能力影响较大，在西南区4个省（市）的7个生态点的地力产量变幅为5 251.4~8 559.2 kg/hm2，4个品种的地力产量对施氮高产处理的平均贡献率73.55%~83.67%；7个生态点的地力产量对施氮高产处理的平均贡献率为80.05%，建立了稻田地力产量与土壤养分的回归预测模型，决定系数76.77%~99.99%。指出地力产量与土壤全氮、全磷呈显著正效应，与海拔、全钾和有效磷呈极显著负效应。西南稻区土壤氮供应不足，需要补施氮肥才能获得较高产量，施磷肥和施钾肥不是西南稻区水稻增产的主攻方向。建立了水稻氮高效施用量及其农学利用率与地力产量的回归预测方程，决定系数分别为66.68%和65.46%。稻田地力产量从5 250 kg/hm2到9 000 kg/hm2，相应的氮高效施用量为192.21~74.46 kg/hm2、氮高效施用量的农学利用率为19.88~4.51 kg/kg，可作为指导大面积高效施氮的参考依据。

In order to improve the nitrogen efficiency of hybrid rice, the soil-based yield, optimized application amounts of nitrogen and its agronomic efficiency of mid-season hybrid rice were studied, using Ⅱ-you 7, Yuxiangyou 203, Chuanxiangyou 9838 and Rong18 you 1015 as materials, in different ecological sites, soil nutrient statuses and N application levels in 2009-2016. Data were analyzed by using variance correlation, correlation regression and partial correlations. The results showed that the soil-based yield were influenced greatly by soil nutrient statuses, the variations of soil-based yield ranged from 5072.1 to 8351.55 kg/hm2 at 7 ecological sites in Southwest China, the contributions of the soil-based yield （the percentage of the soil-based yield in the fertilized yield）ranged from73.55% to 83.67% on the average of four varieties and 80.05% on the average of seven locations, the regression forecasting model were established between the soil-based yield and soil nutrient statuses（R2 ranged from76.77% to 99.99% ）. There were significant positive effects between the soil-based yield and total nitrogen, total phosphorus of soil，and has significant significantly negative effects with altitude, total potassium and effective phosphorus, respectively. Need to fill nitrogen supply to obtain rice high yield because of the soil nitrogen deficiency, P and K application is not the main direction for increasing rice yield in the Southwest area China. Regression equations were established respectively between optimized application amounts of nitrogen as well as its agronomic efficiencies and the soil-based yield in rice（R2 66.68% and 65.46%）. Applying optimized application amounts of nitrogen ranged from 192.21~74.46 kg/hm2 or the agronomic efficiencies ranged from 19.88~4.51 kg grain/kg N as the soil-based yield ranged from 5 250 kg/hm2 to 9 000 kg/hm2, which would be used as the scientific basis for the determination of efficient applied N amount for full scale rice cultivation.