小麦渍害光谱特征分析

Spectral Characteristics Analysis of Wheat Damaged by Subsurface Waterlogging

理清小麦渍害光谱特征是大尺度渍害遥感监测的基础,也是运用光谱特征实现无损、快捷鉴别小麦渍害的前期条件,迄今为止未见对小麦渍害光谱特征的相关研究。该研究通过田间实验分析了8个小麦品种（郑麦9023、西农223、漯6010、富麦168、鄂麦23、鄂麦19、广源11-2、农大195）受渍后叶片和冠层的光谱特征与没有渍害小麦光谱特征的差异,研究表明：受渍后叶片光谱反射率较正常叶片的差异主要表现在645～680 nm区间（红光波段）,较正常值偏高;757～917 nm区间（近红外波段）,较正常值偏低;1 428～1 456 nm区间,较正常值高;1 641～1 684 nm区间,较正常值低,主要原因：一是渍害导致叶片叶绿素光合作用能力下降,二是叶片失水引起水势降低,建议用归一化水指数（NDWI）的差异值反映小麦受渍情况,同时分析了不同小麦品种受渍时与受渍后NDWI指数随时间的变化特点,发现其变化特征与小麦品种的抗性有关;受渍后小麦冠层的所有波段光谱反射率均低于正常小麦,建议用670～2 400 nm光谱反射率的均值差异反映小麦受渍情况。

Spectrum analysis of crop that affected by subsurface waterlogging is the foundation of surface waterlogging monitoring by remote sensing in large scale.It is also the prerequisite of achieving non-destructive,quick identification of wheat subsurface waterlogging damage with spectral features.But there is no papers report about spectrum analysis of crop affected by subsurface waterlogging so far.The paper analysis the spectral features difference of 8 species（zenmai9023,xinong223,luo6010,fumai168,emai23,emai19,guangyuang11-2,nongda195） between affected subsurface waterlogging and normal in leaf and canopy model using field experiment.The results shows that the leaf spectrum reflectivity value of wheat affected by subsurface waterlogging is high in 645～680 and 1 428～1 456 while it is lower in 757～917 and 1 641～1 684 nm.The main reason is that the subsurface waterlogging causes the leaf chlorophyll photosynthetic capacity decreased and leaf water loss.It is suggested to use NDWI（normal differential water index） value to indicate the damage degree of wheat subsurface waterlogging disaster.The changes of the NDWI index value is analyzed with time when difference wheat species demerged by subsurface waterlogging.It is found that the main factors caused the changes of the NDWI index value with time is related with resistance of variety.The canopy spectrum reflectivity value of wheat affected by subsurface waterlogging is low in all spectrum area.It is suggested to use average value in 670～240 nm to indicate the degree of wheat subsurface waterlogging disaster.