基于光谱植被指数的冬小麦叶绿素含量反演

植物功能叶的SPAD值与其氮素和叶绿素有较强的相关性,研究功能叶SPAD与其冠层光谱的关系,对实现植株叶绿素含量快速、无损检测具有重要意义。本文通过对冬小麦生育期的冠层原始光谱进行一阶导数变换,研究其功能叶片SPAD值与冠层光谱的相关性,对监测冬小麦叶绿素含量的敏感波段进行了提取,并建立了叶绿素含量与冠层反射光谱的定量关系。结果表明,基于小麦冠层原始光谱反射率、冠层光谱导数反射率与SPAD的相关系数曲线,提取的各形式下冬小麦叶绿素含量的敏感波段分别为500、690、760和470、630、723nm;并构建了冬小麦叶绿素含量的预测模型,以FDNDVI(630,723)预测模型较好,其R2可达0.9485,模型验证参数R2、MRE和RMSE分别为0.8099、0.0294和1.805,拟合效果较好,表明该模型能有效地对冬小麦叶绿素含量进行预测。该研究结果可为冬小麦长势监测提供一定的理论参考。

Simulating the Content of Chlorophyll in Winter Wheat Based on Spectral Vegetation Index

The SPAD value of plant leaf is significantly correlated with the content of chlorophyll and nitrogen level,and it is important to monitor the chlorophyll content rapidly and non-destructively.The first derivative of the winter wheat canopy spectral reflectance was converted,and the correlation between spectrum and the leaf SPAD was analyzed at the growth period of winter wheat.The sensitive bands for monitoring the leaf SPAD were determined,and the quantitative relation between leaf SPAD and canopy reflectance spectra were established.The results showed that the sensitive bands for monitoring the winter wheat leaf SPAD were 500 nm,690nm,760 nm and 470 nm,630nm,723 nm,respectively,based on the correlation coefficient between the winter wheat canopy spectral reflectance and the first derivative and leaf SPAD.The spectral parameters and the prediction model for monitoring winter wheat chlorophyll content was constructed,the regression coefficient R2 of the estimated model based on the FDNDVI（690,760）was 0.9485,and the calibrated parameters of predicted model R2,MRE and RMSE were 0.8099,0.0294 and 1.805,respectively.It was also concluded that the monitoring model could effectively estimate the winter wheat leaf chlorophyll content,and this was proved to be an effective method for monitoring wheat growth.