【作者】 鲍彪；

【导师】 毕华兴；

【作者基本信息】 北京林业大学 ， 自然地理学， 2013， 硕士

【摘要】 果农间作是晋西黄土区农林复合的一种典型模式,其中,大豆是当地农民选择的一种常见间作作物。由于大豆是典型的喜温短日作物,间作系统内光能竞争会对大豆生长产生明显的影响。为探明弱光胁迫对大豆生长的影响机理,本研究通过四种不同透光率的遮阴网覆盖(透光率分别为100%(CK)、70%(T1)、50%(T2)、30%(T3)),模拟了不同光强在各关键生育期对作物大豆光合特性和产量性状的影响。主要研究结果如下：1、遮阴后能明显改变小气候。随着光强的减弱,光合有效辐射强度、近地表气温和地温均呈下降趋势,同时空气相对湿度会增加,说明遮阴具有降温增湿的作用同时能减少光合有效辐射。2、遮阴处理对大豆的光合特性产生了明显影响。随着光强的降低,植物叶片叶绿素相对含量、土壤含水量增高,净光合速率、蒸腾速率和水分利用效率均呈下降趋势,光补偿点和光饱和点也随之降低,说明该品种大豆具有一定的耐阴能力；遮阴后叶片气孔导度降低,但细胞间C02浓度升高,说明是由非气孔限制因素导致作物光合速率降低。3、弱光下大豆茎叶生物量和产量均受影响。大豆株高、茎叶生物量和叶面积指数随遮阴程度的增加均呈先增加后降低的趋势,当遮阴率超过50%时,作物的生长和生物量均会明显下降,说明大豆虽具有一定的适应弱光环境的能力,但重度遮阴则会抑制作物生长；遮阴后大豆叶片厚度、比叶重和产量较全日照处理均明显下降,说明弱光会削弱大豆生产力,这种削减作用强于大豆本身的适应能力。研究结果表明大豆净光合速率的降低是导致大豆产量下降的直接原因,而导致净光合速率减弱的主要因素是遮阴后光合有效辐射强度的降低。更多还原

【Abstract】 Fruit-crop-intercropping is one of the typical models in agroforestry systems in loess region of west Shanxi.Soybean is a common crop which farmers adopt to plant under the fruit. Competition for light in this system would influence the growth of soybean which is atypical kind of short-day crop which favors temperate weather. In order to explore the influence mechanism of low-light stress on soybean growth, this study investigated the effects of different light intensities on photosynthetic characteristics and yield characters of soybean during each key phonological period by four kinds of light treatment.(Transmittance was CK (100%), T1(70%), T2(50%) and T3(30%) respectively.) The main results are as follows:1. Microclimate was obviously changed after shading. With the decrease of light intensity, there was a decreasing trend in photosynthesis active radiation, near-surface air temperature and ground temperature. And air relative humidity increased at the same time. It could be concluded that shading can decrease temperature and photosynthesis active radiation and increase humidity.2. Shading treatment influenced soybean photosynthetic characteristics. With the decrease of light intensity, content of chlorophyll in leaves and soil water content increased while net photosynthetic rate, Transpiration Rate and water use efficiency all decreased. Light compensation point and light saturation point decreased as well. It suggested that this kind of soybean could tolerant shade. Leaf stomatal conductance decreased after shading but intercellular CO2concentration increased. It can be inferred that non-stomatal limitation resulted in decrease of crop photosynthetic rate.3. Stem-leaf biomass and yield of soybean were influenced by low light. Soybean height, the stem-leaf biomass and leaf area index increase and later decrease with the increase of shading degree. When transmittance was lower than50%, both soybean growth and the above-ground biomass decreased obviously. It indicated that this kind of soybean could adapt to low light environment but over shading would inhibit plant growth. Leaf height, specific leaf weight and yield of soybean decreased evidently after shading. It illustrated that low light could weaken soybean productivity and the weakening effects were more obvious than crop adaptability.The result showed that the decrease of net photosynthesis rate of bean directly caused decline of bean production.While the main factor that brought out the decrease of net photosynthesis rate turn out to be the weakening of photosynthetically active radiation after shading.更多还原