夏玉米冠气温差及其影响因素关系探析

测定了夏玉米主要生育期四个不同水分处理的冠层温度、气温、土壤含水率、叶面积指数和株高,分析了冠气温差与土壤含水率、叶面积指数及株高间的关系。结果表明:不同的灌溉水质和灌溉量措施对夏玉米冠气温差有显著的影响;中午12~14时左右H1高度(2/3株高)处的冠气温差较H2高度(H1+50 cm)更能反映作物和土壤的水分特征,可以用此时刻的卫星遥感冠层温度结合地面气象站数据监测作物和土壤的旱情;80~100 cm土层的土壤体积含水率与节水灌溉处理的冠气温差之间存在良好关系(α=0.05),0~80 cm四个土层中以中午20 cm和40 cm处的土壤体积含水率与冠气温差相关关系最好且稳定,可以利用此关系评价作物的缺水状况;充足灌溉下的夏玉米主要生育期的叶面积指数与冠气温差也有显著的相关关系,节水灌溉下二者关系不显著,说明水分充足条件下叶面积指数对冠气温差的影响更大;株高与不同水分处理的冠气温差也有一定的相关关系,冠层2/3高度处二者的相关系数分别为:0.7027(淡水节水处理)、0.4150(淡水充足处理)、0.3683(咸水节水处理)、0.3062(咸水充足处理)。这为区域上遥感反演夏玉米冠气温差进而监测农田蒸散和土壤含水率提供了试验依据。

Analysis on the Factors Affecting Summer Maize Canopy-air Temperature Difference

The canopy temperature,air temperature,volumetric soil water contents,leave area index and crop heights of four different water treatments during the growth stage of summer maize(from July to September)were detected,and the relationships among canopy-air temperature difference and volumetric soil water content,leave area index,crop height were analyzed.The results indicated that the canepyair temperature difference was impacted greatly by water quality and the amount of irtigation.the canopy-air temperature difference on height H1(two thirds of crop height) at 12:00~14:00 can reflect crop and soil water status than that at H2 Height Therefore it was possible to monitor the agricultural drought by satellite remotely sensed canopy temperature at noon.In addition,a significant curve correlation between volumetric soil water content at depth of 80~100cm and canopy-air temperature difference of water-saving irrigation treatment(α=0.05),and between volumetric soil water content at depth of 20~40cm and canopy-air temperature difference for all different irrigation treatments was found.These relationships can be possibly used to evaluate crop water stress.Leave area index was well related to canopy-air temperature difference in full irrigation treatment,and crop height also had certain relationship with canopy-air temperature difference in all irrigation treatments,with R~2 value of 0.7027(fresh watersaving irrigation),0.4150(full fresh water irrigation),0.3683(salty water-saving irrigation),0.3062(full salty water irrigation) respectively.The results of current study provide a field evidence for cropland evapotranspiration and soil water content monitoring based on remotely sensed canopy temperature at regional scale.