不同生育时期遮阴对大豆形态性状和产量的影响

间套作是提高土地利用率，促进农作物高产的重要技术，而遮阴限制间套作大豆产量，且间作和套作大豆被遮阴的生育时期不同。为明确不同生育时期遮阴对大豆形态性状和产量的影响，2010-2012年用透光率50%的遮阳网对桂夏2号、南豆12、南冬抗22、E61和C103遮阴处理，结果表明，不同生育时期遮阴对各形态指标影响程度不同，前期遮阴(VER1和VER2)对主茎长、主茎长/茎粗等主茎形态性状有(极)显著影响，主茎长、主茎长/茎粗比值平均比对照分别高45.75%，93.64%；后期遮阴(R1R8和R2R8)对分枝数和底荚高度等形态性状有(极)显著影响，分枝数平均比对照低29.97%，底荚高度平均比对照高28.59%；各品种产量受前后期遮阴影响程度不同，R/V比值低于1.4的品种产量受前期遮阴影响更大，R/V比值大于等于1.5的品种产量受后期遮阴影响更大；相关分析和通径分析结果表明，主茎长、第一节间长、分枝高、主茎长/茎粗比值和主茎长/分枝数比值与单株产量呈极显著负相关，分枝数与单株产量呈极显著正相关，主茎长/茎粗比值和主茎长/分枝数比值是间接反映大豆产量高低的重要指标。

Effects of Shading at Different Growth Stages on Different Traits and Yield of Soybean

Intercropping and relay-intercropping are important technologies to improve land utilization rate and crop yield, but their yields are limited by shading, which is different for intercropped soybean and relay-intercropped soybean at different growth stages. To clear the effect of shading at different growth stages on morphology and yield of soybean, we treated Guixia 2, Nandou 12, Nandongkang 22, E61, and C103 with the 50% transmittance shading net using the natural light as control. The results showed that effects of shading on different morphological characters were different at different growth stages, showing a significant influence on length of main stem and main stem length/stem diameter during the early growth period (VER1 and VER2). Compared with control, the main stem length and main stem length/stem diameter were increased by 45.75% and 93.64% respectively. Shading had significant influence on the number of branches and the height of lowest pod at the late growth stage (R1R8 and R2R8). Compared with control, the number of branches was decreased by 29.97% and the height of lowest pod was increased by 28.59%. The effects of shading on yield of cultivars with different growth periods were different, the cultivars with R/V below 1.4 was affected significantly by the early growth period shading, the cultivars with R/V equal to or greater than 1.5 was easily affected by the late growth stage shading. Results of correlation analysis and path analysis showed main stem length, first internode length, branch height, stem length/stem diameter and stem length/branch number were negatively correlated with yield per plant significantly, branch number was positively and significantly correlated with yield per plant, main stem length/stem diameter and main stem length/branch numbercould be key indexes for yield per plant.