田间灰霾模拟实验的塑料膜光学特征分析

通过在大田利用塑料膜进行遮阴实验,可发现灰霾对农作物生长发育及产量的影响。研究对选取进行模拟灰霾实验用的塑料膜的光学特性进行分析;并通过长期观测得到的太阳辐射值与大气气溶胶光化学厚度(AOD)建立关系,得到所选塑料膜代表的灰霾水平。结果表明实验选取的3层12丝的PE塑料膜进行遮阴,使太阳总辐射下降30%,散射辐射增加20%,太阳辐射可见光波段的强度占太阳总辐射强度的比例不变及遮阴后的太阳辐射仍具有灰霾天的太阳辐射各向异性的特点;且塑料膜代表的AOD水平约为0.5左右,为重度灰霾水平。研究为灰霾辐射效应对农作物产量影响实验提供实验设计依据,也可为大棚设施农业中塑料膜对辐射的影响提供参考。

An analysis of plastic film optical property in shading experiment simulating haze effects on crop yield

The influence of haze on crop growth and yield can be found by the shading experiment in field, which applies plastic films to simulate haze. In the study, analyses of the optical properties of plastic films were analyzed. And, based on the long-term solar radiation measurement, the relationship between the global solar radiation and aerosol optical depths (AOD) was set up to calculate the level of haze that plastic films simulated. The results show that shaded by the three layers PE plastic film weaved by 12 threads in the field decreased global solar radiation by 30% and increase diffuse radiation by 20%. The proportion of the visible light intensity in global solar radiation intensity was not changed under shading condition. The solar radiation under shading was still anisotropy, which was the same to the solar radiation property in haze. The level of AOD simulated by three layer PE plastic film is about 0.5, which was heavy haze. The study provides bases for experimental design about the impacts of haze radiation effects on crops, and provides references for the selection of plastic film in agricultural facilities.