日光温室黄瓜冠层中太阳辐射分布规律测定分析

Analysis of Solar Radiation Distribution at the Cucumber Canopy in Sunlight Greenhouse

为研究日光温室内黄瓜冠层中太阳辐射分布规律,观测了黄瓜冠层内的太阳辐射分布情况,分析其与叶面积系数的相关性。结果表明,晴天温室南面黄瓜冠层中太阳辐射最强,北面和中间较弱,阴天差异较小。太阳辐射在冠层内垂直分布随高度减小而衰减,均呈"S"型变化趋势。其中光合有效辐射(PAR)衰减幅度最大,地面PAR仅为冠层顶部的6.1%,散射辐射衰减程度最小,地面散射辐射为冠层顶部的32.3%。太阳辐射透过率在不同高度随叶面积系数的增加而减小,表现为指数关系:Rt=Ae-B×LAI。无论晴、阴天光合有效辐射的消光系数较其他辐射消光系数大,散射辐射最小。

In order to study solar radiation distribution of cucumber canopy in sunlight greenhouse,the solar radiation were measured,and the correlation of solar radiation and leaf area index（LAI） was analyzed.The results showed that in north-south direction,solar radiation of cucumber canopy was the strongest in the south in sunny days,and solar radiation was weaker in north and in the middle,and this difference was smaller in cloudy days;the solar radiation was decreased vertically from the top to bottom of cucumber canopy,and the vertical change trend of solar radiation looked like a ＂S＂ curve;the attenuation extent of photosynthetically active radiation（PAR） was the biggest,and the PAR at the bottom was only 6.1% of that at the top;and the attenuation extent of diffuse radiation was the smallest,and the diffuse radiation at the bottom was 32.3% of that at the top;the rate of radiation transmission（Rt） was decreased with increase of LAI,which obeyed a function of Rt=Ae-B×LAI.No matter on sunny days or cloudy days,the extinction coefficient of PAR was bigger than that of other radiations,and smaller than that of diffuse radiation.