渭北黄土区农林复合系统光能竞争与生产力

Light competition and productivity of agroforestry system in loess area of Weibei in Shaanxi

农林复合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.本文以该区具有代表性的核桃/李子与大豆(秦豆8号)/辣椒(陕椒981)农林复合模式为对象,研究了复合系统内大豆、辣椒的光合作用、生长和产量等情况.结果表明:不同种植模式下,大豆、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.叶片水势与大豆、辣椒的光合速率、地上部分生物量以及产量呈不相关或负相关.而10～20cm土壤含水量与大豆的生物量和产量,以及辣椒的地上部分生物量呈正相关.大豆、辣椒产量与其光合有效辐射呈显著正相关.说明在农林复合系统中,光能竞争是导致间作大豆、辣椒产量下降的主要原因.

Agroforestry is the most effective way for the restoration of disturbed land on Loess Plateau and the development of poorly local economy. Taking the tree-based intercropping systems of walnut or plum with soybean or pepper in the loess area of Weibei as test objects, the photosynthesis, growth, and yield of soybean （ Qindou 8 ） and pepper （ Shanjiao 981 ） in the systems were studied. The results showed that the photosynthetic active radiation （PAR）, net photosynthetic rate （Pn） , growth, and yield of individual soybean or pepper plants were significantly decreased, with the effects increased with decreasing distance from tree rows. Leaf water potential was not significantly or poorly correlated with the Pn, growth, and yield of the two crops. However, there were significant positive correlations between the soil moisture content in 10-20 cm layer and the biomass and yield of soybean, and the above-ground biomass of pepper. PAR was highly correlated With the yield of both crops, which indicated that light competition was one of the key factors leading to the decrease of crop yield.