Detection of vegetation light use efficiency based on chlorophyll fluorescence spectrum

In this paper, a new method was presented to detect LUE based on the remotely sensed chlorophyll fluorescence (ChlF) signals. A diurnal change experiment was carried out to acquire the vegetation photosynthesis, canopy spectra and chlorophyll fluorescence parameters. The solar-induced chlorophyll fluorescence signals were separated from the canopy spectra at 688 and 760 nm based on the Fraunhofer Line Depth algorithm. The LUE model (fluo-LUE) was established based on the ChlF signals at the two oxygen absorption bands, and it was also compared with the LUE model (PRI-LUE) based on photochemical reflectance index (PRI). The result showed that LUE was highly significantly correlated with the PSII (photosystemⅡ) Yield of quantum efficiency(ΦPSII) (R2=0.802), which proved the possibility to detect LUE based on the remotely sensed ChlF signals. And LUE was significantly correlated with the ChlF signals at 688 and 760 nm. Compared with PRI-LUE model (R2=0.646), the correlation coefficient of fluo-LUE model was more significant (R2=0.799). Therefore, Chlf Signals could track the diurnal changes of LUE much better than the PRI. These research results show the solar-induced Chl signals might provide a prospective method for detecting LUE.