中文摘要：

大豆冠层截获的太阳辐射强度是其产量和产量构成要素的重要决定因素。通过对3个粒重不同的大豆品种（系）生殖生长期进行不同的光处理，研究了田间条件下，高密度（54株·m^-2）、中密度（27株·m^-2）和低密度（14株·m^-2）群体光富集及遮阴对大豆植株产量及其构成特征的影响。结果表明：光富集处理显著增加大豆单株荚数和产量，在低、中和高密度条件下，不同品种（系）单株产量增加幅度分别为26．2％～57．2％、27．7％～71．7％和10．8％～61．4％。遮阴显著降低大豆荚数和产量，不同密度条件下，单株产量相应减少幅度分别为37．1％～46．1％、34．4％～49．7％和41．7％～55．0％。光富集显著增加大豆主茎中下部节位的荚数，在低密度群体下，3个品种大豆主茎1～6节位的荚数分别由7．5个增加到17．3个、5．6个增加到10．1个和6．9个增加到17．2个，并显著减少底部节位的空荚率。光富集和遮阴有增加和减少每荚粒数的趋势，在低密度群体下，光富集使海339每荚粒数显著上升，由2．17上升到2．36，在中密度和高密度有使其每荚粒数上升的趋势但差异不显著。在低密度和中密度下，黑农35每荚粒数显著上升，分别由1．93和1．78上升到2．26和2．13，在高密度下，光富集也使垦农18每荚粒数显著上升，由1．89上升到2．08。在低密度下，遮阴使垦农18每荚粒数由2．17减少到1．97。光富集和遮阴对粒重也有一定影响，在低密度群体下，遮阴增加垦农18和海339粒重8％～11％，而在高密度群体下，遮阴降低海339百粒重17％，百粒重的变化与种植密度及品种有关。单株荚数和粒数的改变是对产量贡献最大的因子。

英文摘要：

Light intensity intercepted by soybean canopy during the reproductive period is an important environmental factor determining soybean yield and yield components. Responses of yield and yield components to light enrichment and shade under varied populations were investigated. The results showed that light enrichment increased pod number and seed yield per plant significantly. Under low, moderate and high density conditions, light enrichment increased seed yield per plant from 26.2% to 57.2% ,27.7% to 71.7% and 10.8% to 61.4% respectively. Shade decreased pod number and seed yield per plant significantly. Accordingly, under low, moderate and high density conditions, shade decreased seed yield per plant from 37.1% to 46.1% ,34.4% to 49.7% and 41.7% to 55.0%. Light enrichment increased pod number of main stem nodes in the central and lower region of soybean plants. Under low density condition,light enrichment increased pod number in H339 from 7.5 to 17.3 at main stem nodes 1 to 6 ,similarly ,from 5.6 to 10.1 in HN35 ,from 6.9 to 17.2 in KN18. Light enrichment significantly decreased pod abscission ratio of main stem nodes in the lower region of soybean plants. Light enrichment and shade respectively increased or decreased seed number per pod. Under low density condition,light enrichment increased seed number per pod in H339 from 2. 17 to 2.36. Under low and moderate density condition, light enrichment increased seed number per pod in HN35 from 1. 93 to 2.26,1.78 to 2.13. Under high density condition, light enrichment increased seed number per pod in KN18 from 1.89 to 2.08. Under low density condition,shade decreased seed number per pod in KN18 from 2.17 to 1.97. Light enrichment and shade also influenced seed size under varied populations. Under low density condition, shade increased seed size at 8%- 11% in H339 and KN18. However, under high density condition, shade decreased seed size 17% in H339. Variation of seed size had closer relation with plant density and variety. Pod number and seed number per plant as the y