中文摘要：

【目的】在玉米大豆间套作种植系统中,高位作物玉米的遮荫常常会导致大豆苗期茎秆细弱,倒伏严重,产量低下。文章在玉米大豆间套模式下,分析遮荫程度对大豆苗期光合产物积累、分配和抗倒性的影响,为建立合理群体结构提供理论依据。【方法】以不耐荫不抗倒型大豆南032-4和强耐荫强抗倒型大豆南豆12为试验材料,设置不遮荫（W0,透光率100%）、一层黑色遮阳网（W1,透光率31.90%）和二层黑色遮阳网（W2,透光率10.83%）3个处理进行室外盆栽试验,测定大豆光合速率、气孔导度、蒸腾速率、胞间二氧化碳浓度、SPAD值、叶面积及各器官生物量积累等光合指标和株高、各节间长度、各节间茎粗、茎秆抗折力、倒伏指数等抗倒伏指标,分析不同遮荫处理下大豆光合特性及抗倒伏相关性状的变化。【结果】随着遮荫程度的增加,2个品种大豆的光合速率、气孔导度、叶面积和SPAD值显著降低,各器官有机物积累量和根冠比显著下降;随遮荫程度增加,大豆倒伏严重,茎秆抗折力和抗倒伏指数显著降低。不同耐荫性大豆品种对不同遮荫程度的响应有差异,与W0相比,强耐荫性大豆南豆12和不耐荫性南032-4的光合速率在W1和W2分别降低了35.6%、99.6%和40.9%、83.6%。强耐荫性品种南豆12在W0和W1干物质积累高于南豆032-4,差异显著,但W2处理下差异不显著（P〈0.05）,表明中度遮荫下大豆的光合速率仍保持较高水平,且强耐荫性品种在遮荫条件下光合产物积累量较高。南032-4的W1和W2处理倒伏率较南豆12分别高出55.9%和2.57%（2014年和2015年2年均值）,W1处理下南032-4表现中度倒伏,南豆12表现为轻度倒伏,而W2处理下南032-4和南豆12均表现为严重倒伏,表明中度遮荫下大豆品种间倒伏差异显著,不耐荫性品种倒伏程度严重。同一遮荫程度下,南豆12抗折力降低幅度（39.8%）高于南032-4（38.425%）,但W1

英文摘要：

【Objective】Under the maize/soybean relay strip intercropping system, shading from high crop maize leads to soybean seedling thinning, lodging and decreasing soybean yield. We studied the effect of soybean photosynthesis and lodging resistance in seeding stage under different shade degrees in the maize/soybean relay strip intercropping system, then provided a theoretical basis for the establishment of a reasonable community population structure. 【Method】 The non-shade tolerance and non-lodging resistant Nan032-4 and the strong shade tolerance and strong lodging resistance Nandou 12 were taken as experimental materials in 2014 and 2015. We designed three light conditions in the outdoor pod experiment, the natural light（W0）, one layer of black sun-shade net（W1）, and two layers of black sun-shade net（W2） with light transmittances of 100%, 32% and 11% respectively. Photosynthetic characteristics such as soybean photosynthetic rate, stomatal conductance, transpiration rate, intercellular CO2 concentration, SPAD values, leaf area and biomass accumulation of each organ and lodging characters, including plant height, each internode length, each internode diameter, stem snapping resistance, lodging resistance index were measured and analyzed. 【Result】The results showed that as the shade increased, photosynthetic rate, stomatal conductance, leaf area and SPAD values, the dry matter accumulation of each organ and root/shoot ratio of the two soybean varieties were all reduced significantly. As shade increased, seedling lodging became serious, with the stem snapping resistance and lodging resistance index also reduced significantly. However, the shade avoidance responses on different shade degrees were significantly different between these two different shade tolerant varieties. Compared with W0, photosynthetic rates of the shade tolerant cultivar Nandou12 and the non-shade tolerance Nan032-4 under W1 and W2 were decreased by 35.6%, 99.6% and by 40.9%, 83.6% respectively. Compared with Nandou12, Nan032-