中文摘要：

以水稻品种南粳45、南粳49、南粳94140和淮稻5号为材料,研究了不同栽插苗数对粳稻冠层光合参数和产量的影响。结果表明：南粳49和淮稻5号在2~4株/穴时能够获得较高产量,而在5株/穴时,产量显著下降;南粳45和南粳94140在不同栽插苗数下均获得稳定产量。南粳49在较低栽插苗数下获得高产是由于有较多的每穗粒数、较大的叶基角、较高的PSⅡ最大光化学效率（Fv/Fm）以及花后不同时期较多的干物质累积;而淮稻5号则还具有较多有效穗数以及生育后期较大叶面积。南粳45和南粳94140是通过其冠层叶基角、光拦截以及最大光化学效率的适应调节,从而达到每穗粒数、千粒质量以及结实率等产量构成因子之间相互协调。说明,供试水稻品种均是具有较强群体调控能力的高产水稻品种类型,栽插密度对其产量的影响均与其高产群体配置和个体的生理功能密切相关,其中南粳49和淮稻5号在2~4株/穴栽插密度下有利于产量潜力的发挥,而南粳45和南粳94140对不同的栽插苗数有较大的适应能力,产量表现稳定。

英文摘要：

Using four high-yielding rice varieties（ Nanjing 45,Nanjing 49,Nanjing 94140,Huaidao 5） as experimental materials,four different planting densities（ 2,3,4,5 seedlings per hill） were set to study the effects of different planting densities on rice canopy,photosynthetic indexes and yield. The results showed that Nanjing 49 and Huaidao 5 achieved high yield at 2 to 4 seedlings per hill,and the yield at 5seedlings per hill deceased markedly. The yields of Nanjing 45 and Nanjing 94140 were kept stable at different planting densities. Nanjing 49 could achieve higher yield at lower planting seedlings due to more spikelet per panicle,larger leaf base angle,higher Fv/ Fmand more dry matter after flowering while for Huaidao 5,it was resulted from more effective panicle,more spikelet per panicle,larger leaf area at late growth stage higher Fv/ Fm,and more dry matter after flowering. Nanjing45 and Nanjing 94140 realized the intercoordination between spikeliet per panicle,1000-grain weight and seed-setting rate through the adaptive regulation of leaf base angle of canopy,light intensity and the maximum Fv/ Fmto keep stable production. It is indicated that as rice varieties capable of population regulation,the yield influenced by planting density was closed related to the population structure and individual plant physiological function. The density of 2-4 plants per hill for Nanjing 49 and Huaidao 5 is in favor of the yield potential. Nanjing 45 and Nanjing 94140 owns great adaptions to different planting densities.