冬小麦冠层高光谱特征与覆盖度相关性研究

在2010年度与2011年度冬小麦生长季大田试验小区,实测了3个播种密度、3个灌水水平下冬小麦冠层的高光谱反射率与覆盖度。分析了冬小麦冠层光谱特征以及不同生育期冬小麦冠层光谱特征参数与覆盖度的相关性,建立了基于光谱特征参数的不同生育期冬小麦覆盖度估算模型。结果表明:从返青到成熟,冬小麦冠层可见光区光谱反射率先减小后增大,近红外区先增大后减小。不同种植密度下,适宜供水冬小麦在可见光波段的反射率依次小于轻度亏水、重度亏水条件下的冬小麦;在近红外波段,规律正好相反。在相关性分析中,传统光谱特征参数和新光谱特征参数与覆盖度在不同生育期均具有较好的相关性。相比以传统光谱特征参数为自变量的冬小麦覆盖度估算模型,基于绿峰峰度的估算模型可以提高冬小麦覆盖度的估算精度。

Correlation between Percentage Vegetation Cover and Hyperspectral Characteristics of Winter Wheat

The winter wheat PVC estimation models based on canopy spectral characteristic parameters were established in different growth periods. The results showed that the winter wheat canopy hyperspectral reflectance in the visible light decreased from reviving to heading stages, then increased from heading to maturing stages, while in the near infrared band, it increased from reviving to heading stages, decreased from heading to maturing stages. Under different crop densities, hyperspectral reflectance of winter wheat canopy with suitable for water supply in the visible light was less than that of slight water deficit and severely water deficit in order, but in the near infrared band, it had opposite conditions. There were good relationships between winter wheat PVC and the spectral characteristic parameters of traditional and new spectral characteristic parameters in different growth periods. Compared with the models of winter wheat PVC which used the parameters of traditional spectrum characteristic as the independent variables, the models based on the kurtosis of green peak can improve the estimation accuracy of winter wheat PVC.