Abstract: In order to definite the response of dry matter accumulation and yield formation of maize to irrigation and nitrogen under different densities，Xundan 509 and Zhengdan 958 were used as materials to study the effects of irrigation amount［reduced irrigation（W1，irrigating 37.5 mm at flare opening and silking stages），full Irrigation（W2，irrigating 75 mm at flare opening and silking stages）］and nitrogen application rate［no nitrogen fertilizer（N0），low nitrogen level（N1，150 kg/ha nitrogen fertilizer），normal nitrogen level（N2，225 kg/hanitrogen fertilizer）］on dry matter accumulation，ear height coefficient，chlorophyll fluorescence parameters（Fv/Fm and Fv/Fo），leaf area index（LAI），yield and its components of maize under different densities［67 500 plants/ha（D1），90 000 plants/ha（D2）］.The results showed that，full irrigation and application of nitrogen both increased dry matter accumulation of population，LAI，Fv/Fm，Fv/Fo，ear height coefficient，yield and its components of two maize cultivars.Simultaneously，the appropriate irrigation amount and nitrogen application rate promoted transfer of dry matter to grain.Increase of density also increased dry matter accumulation of population，LAI and grain yield，while had adverse effects on Fv/Fm and Fv/Fo.Two maize cultivars generally had the highest dry matter accumulation of population，LAI and grain yield under D2W2N2 treatment. Compared with D1W1N0 treatment，the yields of Xundan 509 and Zhengdan 958 increased by 60.76% and 55.38% under D2W2N2 treatment respectively.Overall，D2W2N2 treatment with nitrogen application rate of 225 kg/ha，irrigating amount of 75 mm at the flare opening and tasseling⁃silking stages of maize respectively，and density of 90 000 plants/ha is the optimal measure to obtain high yield under high density.

Key words: Maize, Irrigation amount, Nitrogen application rate, Density, Dry matter accumulation, Yield

摘要： 为明确不同密度水平下玉米干物质积累和产量形成对水氮调控的响应，以浚单509和郑单958为材料，研究不同灌水量［减量灌溉（W1，大喇叭口期和抽雄吐丝期分别灌溉37.5 mm）和充分灌溉（W2，大喇叭口期和抽雄吐丝期分别灌溉75 mm）］和施氮量［不施氮（N0）、低氮水平（N1，150 kg/hm²）和正常氮水平（N2，225 kg/hm²）］对不同密度［67 500株/hm²（D1）和90 000株/hm²（D2）］下玉米干物质积累、穗位高系数、穗位叶叶绿素荧光参数（Fv/Fm和Fv/Fo）、叶面积指数（LAI）和产量及其构成因素的影响。结果表明，充分灌溉和增施氮肥均提高2个玉米品种群体干物质积累量、LAI、Fv/Fm和Fv/Fo、穗位高系数、产量及其构成因素，且适宜的水氮措施可促进高密度水平下玉米干物质向籽粒的转运。此外，提高密度也提高了2个品种群体干物质积累量、LAI和产量，但对叶绿素荧光参数Fv/Fm和Fv/Fo产生不利影响。2个玉米品种总体上均以D2W2N2处理群体干物质积累量、LAI和产量最高，与D1W1N0处理相比，D2W2N2 处理浚单509 和郑单958 产量分别提高60.76% 和55.38%。综上，D2W2N2 处理即在90 000株/hm²密度水平下，施氮225 kg/hm²，大喇叭口期和抽雄吐丝期分别灌水75 mm为玉米适宜的密植高产水氮调控措施。

关键词: 玉米, 灌水量, 施氮量, 密度, 干物质积累, 产量