中文摘要：

以湘杂棉8号为材料,于2008-2009年在南京研究了不同密度对杂交棉群体结构、光合势、干物质积累量与分配、产量的影响。结果表明：盛铃期以前,棉花叶面积指数、光合势、群体生长率随密度的提高显著增大,之后,高密度（3.9万株.hm-2以上）棉花的叶面积指数、光合势与群体生长率均较低,且铃数与铃重也降低,难以获得高产。综合分析,长江流域下游棉区抗虫杂交棉适宜密度为3.0万株·hm-2左右。

英文摘要：

In order to increase cotton yield in lower reaches of Yangtze River Valley,we studied the effects of planting density on canopy structure,photosynthetic potential,dry matter accumulation and its distribution,and yield formation of insect-resistant hybrid cotton at Jiangsu Academy of Agriculture Sciences in 2008 and 2009 with field experiment.The results showed that leaf area index increased with planting density before boll peak stage,same as photosynthetic potential and population growth rate.But in later growth period,the photosynthetic potential and population growth rate in high planting density treatments were low due to the decline of leaf area index.Both the boll number and boll weight decreased.Therefore,the planting density should be paid more attention in lower reaches of Yangtze River Valley.All results suggested that medium density（30000 plants per hectare） was the optimal planting density.