小麦倒伏后茎秆和叶片在探测视场中的比例及植株组分的受光条件发生了变化,其冠层光谱特性也随之发生改变,所以利用遥感监测倒伏是可能的。首先,分析了叶片和茎秆组分的光谱特点,解释了倒伏后冠层光谱的变化特点,即光谱反射率随倒伏角度的增加而增加。其次,利用倒伏后冠层光谱反射率在可见光波段的相对增幅高于近红外波段的特点,利用实测数据分析和建立了归一化差异植被指数NDVI随倒伏角度的增加而降低的规律及模型。最后,采用2003年4月7日和5月9日倒伏发生前后的2景LandsatETM卫星影像,利用倒伏前后的NDVI值的变化,成功监测了小麦倒伏的发生程度。

The ratio and illumination ofwheat plant’s leaf and stalk in spectrometer’s field of viewchange due towheat lodg-\ning, so it is possible to detect the lodging grade by remote sensing technique. Firstly, the spectral difference between leaf and\nstalk is analyzed, and howcanopyspectral reflectance increaseswithlodge angle is explained. Secondly, becausethe relative in-\ncrease of spectral reflectance in visible bands is largerthan in near infrared bands, the significant negative correlationmodel be-\ntween lodging angle andNDVIwas built by statistical analysis. Finally, two LandSat ETM satellite images of April 7 (before\nlodging) andMay9, 2003 (after lodging) were selected, andthe ratioofNDVIderived fromthetwo imageswasstatistically cor-\nrelated to the lodging grade, and the lodging grade was successfully regressed.