Detection of Vegetation Light-Use Efficiency Based on Solar-Induced Chlorophyll Fluorescence Separated From Canopy Radiance Spectrum

Photosynthetic light-use efficiency (LUE) is an important indictor of plant photosynthesis, but it is not yet assessable by remote sensing. The recent research on the separation of solar-induced chlorophyll fluorescence (ChlF) from the hyperspectral data indicates the possibility of detecting LUE. In this study, we presented a novel solution for monitoring LUE from hyperspectral data. Experiments at leaf level and canopy level were carried out on winter wheat (C3 plant functional type) on 18 April, 2008 and summer maize (C4 plant functional type) on 5 July, 2008 by synchronously measuring daily canopy radiance spectra and leaf or canopy LUE. The solar-induced chlorophyll fluorescence signals at 760 nm and 688 nm were separated from the reflected radiance spectra based on Fraunhofer lines in two oxygen absorption bands. The results showed that LUE was inversely related to the relative chlorophyll fluorescence. The leaf-level LUE models for winter wheat were built based on relative ChlF at bands of 688 nm (R²=0.78) and 760 nm (R²=0.64), whereas correlation coefficients of the canopy-level LUE models for summer maize on relative ChlF at the same bands were 0.63 and 0.77, respectively.