半湿润雨养农业区油菜冠层反射光谱与覆盖度的相关分析

Correlation analysis of canopy reflectance and coverage of rape in semi-wet rainfed agriculture area

以黄土高原甘肃庆阳西峰为半湿润雨养农区典型代表,分析研究油菜营养生长阶段苗期、蕾苔期和生殖生长阶段初期开花始期的冠层反射光谱特征与其覆盖度的相关性。结果表明,这几个时期油菜覆盖度与450、550、650、850、1650nm波段反射率存在明显的相关关系,尤其是蕾苔期,相关关系达到极显著水平。另外,研究了10个常用的植被指数同油菜覆盖度间的相关关系,这10个植被指数同油菜覆盖度存在着极显著的相关关系,相关性高于同单波段反射率间的关系。并且,利用各时期最优的2个植被指数建立了油菜覆盖度线性及非线性回归监测模型,方程的拟合度都较好。苗期,线形和非线性回归模型拟合程度差异不大,蕾苔期,以线性方程拟合精度较其它方程高;开花始期则以指数模型拟合精度高。

The relationship between coverage and canopy reflectance of rape in seedling, budding and early flowering stage in Xifeng district of Qingyang City was studied. The result showed that rape coverage had a distinct correlation with the spectral reflectance of 450,550,650,850 and 1 650 nm band. And especially in budding stage, this correlation was very significant. In addition, the correlations of ten normal vegetation indexes with coverage were proved, which are more significant than those with single band reflectance. By using the best two VI monitoring models about coverage were constructed, and the fitting degrees are better. But in seedling stage the differences of linear and non-linear regression models are indistinct, in budding stage the linear equation is better, and in early flowering stage the exponential equation is better.