光能竞争对农林复合生态系统生产力的影响

Effects of light competition on crop productivity in an intercropping agroforestry ecosystem

农林复合生态系统是改善渭北黄土区脆弱生态环境、促进该区域经济发展的重要举措。以该区具有代表性的核桃（Juglans regia L.）、李子（Prunus salicina）,绿豆（秦豆6号）、辣椒（陕椒981）农林复合模式为对象,研究不同农林复合系统对光能分布、农作物生长、生产的影响。研究结果表明,不同复合模式下,玉米、辣椒的光合有效辐射、光合速率、生物量及产量均有不同程度的下降,且距树行愈近,影响愈大。叶片水势与玉米、辣椒的光合速率、地上部分生物量以及产量不相关或负相关。而10-20 cm土壤含水量与绿豆的生物量和产量以及辣椒的地上部分生物量正相关。但绿豆、辣椒的生产量与其光合有效辐射呈显著正相关性,这说明,农林复合系统中光能竞争是导致间作绿豆、辣椒产量下降的主要原因。

Agroforestry is the most effective way to restore the disturbed lands on the Loess Plateau and to develop the currently poor local economy.In order to study the potential benefits of tree-based intercropping systems,photosynthesis,growth and yield of mung bean（Qindou 6） and pepper（Shanjiao 981） were studied by measuring photosynthetic active radiation（PAR）, plant water deficit and soil moisture in a 4-year-old plantation of walnut（Juglans regia L.） and plum（Prunus salicina） grown at a spacing of 5 m×3 m on the Loess Plateau.The effects of tree competition significantly reduced the PAR,the Net photosynthetic rate（Pn）,growth and yield of individual mung bean or pepper plants growing near（within 1m near） to tree rows.In 2007,daily plant water deficits were not significantly correlated with the Pn and growth and yield of the both crops.However,the soil moisture（20cm depth） was significantly correlated with biomass and yield of the crops.The PAR was highly correlated with growth and yield of the both crops,which indicated that competition for light is one of the key factors impacting crop yield.Possible remediation strategies are suggested that may reduce competitive interactions between the tree and crop species.