Derivative Spectrum Remote Sensing and Its Application in Measurement of Rice Agronomic Parameters of Rice

The objective of this paper is to analyze the elimination of background signals(such as wet soil, water and so on) using derivative canopy spectra of rice under different nitrogen status. Application of this technique for tackling analogous problems such as interference from soil background reflectance in remote sensing is proposed. Potential areas for the application of this technique in remote sensing are considered. The optimum spectral bandwidth for smoothing is less than 10 nm. When the derivatives are applied to determine the agronomic parameters, there is a shift phenomenon of the red edge. The red edge positions move to longer wave bands till booting stage and move to shorter bands after booting stage with nitrogen increasing. The red edge parameters in the first derivative reflectance curve (wavelength, amplitude and area of the red edge peak) were studied to evaluate rice leaf chlorophyll, LAI. A high correlation was found between chlorophyll A content of top leaves and the wavelength of the red edge position and between LAI and the red edge parameter. Then, the red edge was proved to be valuable for assessment of rice upper leaves chlorophyll contents. But a correlation was not found between chlorophyll B content of leaves or carotenoid and the wavelength of the red parameters. Some red edge parameters are one of the best remote sensing descriptors. The feasibility of using derivative spectra to measure some agronomic parameters is verified.