冬小麦冠层光谱红边参数的变化及其与氮素含量的相关分析

通过对不同氮肥条件下的小麦植株由上而下进行器官疏剪,分析了不同处理下冠层光谱反射率及其红边参数的变化。结果表明,冠层光谱反射率因不同肥力、不同疏剪处理而有较大的差异,表现出不同程度的红边的“红移”和“蓝移”现象。各处理的红边曲线形状均出现双峰现象,表现为第二个峰值高于第一个峰值,并且均为N1>N2>N0。相关分析表明,随着由上而下的疏剪处理,不同叶位叶片光谱反射率对冠层光谱的贡献增加,并且其红边参数与相应的叶片全氮含量的相关系数也增加,部分达到显著或极显著相关水平。该结果为利用下部缺素敏感叶片的光谱特征进行小麦养分的及时补充提供了可靠的理论依据。

Spectral Red Edge Parametric Variation and Correlation Analysis with N Content in Winter Wheat

Canopy spectral reflectance and red edge parameters were compared in different nitrogen fertilizer levels and different removing treatments in this study.It was also analyzed about the correlation between nitrogen content of ear,leaf,stem and their corresponding red edge parameters.The results indicated that canopy spectral reflectance changed with different treatments and nitrogen levels.In addition,it showed that red edge position moving to the longer or shorter wavelength in different degree,which not only reflected that senescence became more and more serious with the leaf position descended,but also showed that disturbance of soil background increased with the vegetation coverage decreased.The first derivative curve of red edge reflectance had two peaks,and the latter peak showed higher than the former one.Furthermore,their first derivative of reflectance showed N1>N2>N0.The correlation between leaf nitrogen content of different leaf position and red edge parameters increased with their contribution to canopy increasing,and some of them were in significant levels.The red edge peak shapes of ears,leaves and stems removed from plants were different for their different nitrogen fertilizer levels.Besides,their first derivative curve of red edge reflectance had three peaks,which was needed to further study.The results can help to understand the contribution of nitrogen content in different organs or leaf position to canopy spectra,and be favor to fertilizing in times using the lower leaf who had more sensitive to nutrient deficiency.