农果复合系统光热资源有效利用Ⅳ.作物生产模拟

Efficient Use of Light and Temperature in Ecosystem of Crops and Fruit Trees Ⅲ. Effect of Crown Shading on Surface Temperauture

在行栽果树条件下，对农田作物（冬小麦、夏玉米、夏大豆）在一级生产水平下的干物质生产作了模拟计算，得到果树在不同行向下作物干物质产量的空间分布。

Changes of temperature of ground surface caused by the shade of fruit tree crown were measured using an infrared thermometer. Two years measurements showed that the decrement value, ΔT (℃), of temperauture of bare ground surface caused by shad of row trees was mainly dependent on transmittance, τ, of sun light through tree crown and flux density, U 0 (μmol m -2 s -1 ), of photosynthetically active radiation in open area, i.e. ΔT=0.0113U 0(1-τ).