在大田试验条件下，以宜香优2115为试验材料，设地力（高、较高、中、低）和施氮量（0、75、150 和225 kg/hm²）两因素处理，探明不同地力条件下施氮量对杂交籼稻干物质积累、转运和产量及氮肥利用率的影响。结果表明，随着施氮量增加，穗前和成熟期干物质积累量有增加趋势；抽穗期至成熟期，随着施氮量的增加，茎叶干物质转运量和茎叶干物质转运对穗部贡献率均呈先增加后降低的趋势；随着施氮量的增加，氮肥吸收利用率、农学利用率和偏生产力，以及千粒重和结实率逐渐降低，每穗粒数和产量先增加后降低，而有效穗数逐渐升高。随着地力条件的降低，穗前、成熟期和穗后干物质积累量、茎叶干物质转运量和茎叶干物质对穗部的贡献率及穗部干物质增加量均呈逐渐下降趋势，氮肥吸收利用率和生理利用率亦有降低趋势，而偏生产力呈先增后降的趋势。水稻有效穗数和产量均随土壤地力的提高而增加，而每穗粒数表现为下降。回归分析表明，在高、较高、中、低地力条件下，水稻可获得的最高产量分别为10 829.94、10 107.20、9 757.30和9 112.37 kg/hm²，其对应的适宜施氮量分别为141.96、165.47、154.86和152.98 kg/hm²。综上所述，中等施氮量能够使杂交籼稻在不同地力条件下获得较高的干物质积累量和转运能力，及较高的氮肥利用率，实现高产稳产。

Under the conditions of field experiment, Yixiangyou 2115 was used as the test material, and two factors of soil fertility (high, relative high, medium and low) and nitrogen application levels (0, 75, 150 and 225 kg/hm²) were set up, the effects of nitrogen application rate on dry matter accumulation, transportation, nitrogen fertilizer utilization rate and yield of hybrid indica rice under different soil fertility condition were studied. The results showed that in the range of 0~225 kg/hm² nitrogen application rate, the dry matter accumulation of before heading and maturity stage increased with the nitrogen application rate increased. From heading stage to mature stage, with the increase of nitrogen application rate, stem-leaf dry matter transport amount and stem-leaf dry matter transport contribution rate to panicle increased first and then decreased. With the increase of nitrogen application rate, the nitrogen absorption utilization rate, agronomic utilization rate and partial productivity, as well as 1 000-grain weight and seed setting rate gradually decreased, the number of grains per panicle and yield increased first and then decreased, while the effective panicle number increased. With the decrease of soil fertility conditions, the dry matter accumulation of before and after heading and mature stage and stem-leaf dry matter transport and the contribution rate of stem-leaf dry matter transport to panicle decreased, the fertilizer-N recovery efficiency and physiological efficiency also decreased, while the partial productivity of applied N first increased and then decreased. The number of effective panicles and yield increased with the improvement of soil fertility, while the number of grains per panicle decreased. Regression analysis showed that under the conditions of high, relative high, medium and low soil fertility, the highest yields of rice were 10 829.94, 10 107.20, 9 757.30 and 9 112.37 kg/hm², respectively, and the appropriate nitrogen application rates were 141.96, 165.47, 154.86 and 152.98 kg/hm², respectively. In conclusion, moderate nitrogen application rate can make hybrid indica rice obtain higher dry matter accumulation and transport capacity under different soil fertility conditions, as well as higher nitrogen fertilizer utilization rate, so as to achieve high and stable yield of hybrid indica rice.