[Objective]The effect of nitrogen fertilization on double-cropping rice planted in middle areas of Guangxi,was investigated to rationalize the application of nitrogen fertilizer in rice production. [ Method ] Field experiments were conducted to investigate the effects of different dosages of controlled-N releasing fertilizer on growth characteristics and yield of rice in Xingbin District of Guangxi during 2008-2009. [Result]The nitrogen fertilizer showed stimulatory effect on growth of early rice, and significantly improved the yield. Compared to the treatment of nitrogen less fertilizer (No), the plant height and effective panicles of early rice in N treatment during two years increased by 16.07 and 28.76％, respectively, total grain number per panicle and seed setting rate increased by 12.54 and 1.34％, respectively, and the average yield of rice increased by 41.26％. However, the effective panicles, toal grain number per panicle, seed setting rate and yield of rice were decreased with the increase of fertilizer dosage above 330 kg/ha N. [Conclusion]Applying 165-330 kg/ha nitrogen fertilizer in rice production was found to be suitable for ensuring high yield of rice and high efficiency of N fertilizer application in middle areas of Guangxi.%[目的]探讨桂中双季稻区水稻氮肥施用效应,为当地水稻生产合理施用氮肥提供理论依据.[方法]2008～2009年在广西来宾市兴宾区进行了不同控释氮肥用量对该地区早稻生长性状、产量以及氮肥农学效率影响的大田试验.[结果]施氮对桂中稻区早稻的生长具有促进作用,能明显地改善水稻的产量结构,与不施氮(No)相比,两年早稻施氮处理的株高与有效穗数分别平均提高16.07%与28.76%,与每穗总粒数与结实率分别平均提高12.54%与1.34%,产量平均提高41.26%,当氮肥施用量＞330 kg/ha时,水稻的有效穗数、每穗总粒数、结实率与产量均随着施肥量的增加而降低.[结论]桂中稻区早稻施氮165～330 kg/ha,既能确保水稻高产,又能保证肥料资源得到高效利用,是桂中地区早稻比较合理的施肥水平.
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