Tracing photosynthetic electron transport rate based on hyperspectral reflectance

Chlorophyll fluorescence is a common approach for understanding leaf photochemical and nonphotochemical processes nondestructively. Among all fluorescence parameters, the photosynthetic electron transport rate (ETR) is a useful indicator of the efficiency of carbon uptake. Traditionally, Pulse Amplitude Modulation (PAM) fluorometry was a key technique for measuring ETR, but it is not applicable for large-scale monitoring. Alternatively, hyperspectral remote sensing has a great potential for this purpose and as thus several indices generated from hyperspectral reflectance have been developed for tracing ETR. In this study, we have extensively examined the performance of twelve early published indices for tracing leaf ETR of a typical deciduous species (Fagus crenata) in a cold-temperate mountainous area. Furthermore, developing of new hyperspectral indices has also been conducted based on both original and first derivative reflected spectra. Results revealed that our proposed index (dmND
_{680, 540, 835}
) was applicable for both sunlit and shaded leaves and had a high robustness, suggesting its potential for a general application.