Tracking photosynthetic injury of Paraquat-treated crop using chlorophyll fluorescence from hyperspectral data

Abstract

Three diurnal experiments were conducted on winter wheat to investigate how solar-induced chlorophyll fluorescence (SIF) responded to Paraquat treatments (a PSI herbicide). First, a slight increase in spectral reflectance in the red region and an obvious decrease in reflectance in the NIR regions was observed due to crop injury from Paraquat. Secondly, a significant increase in SIF at 688 nm, but a significant decrease at 760 nm was observed. The opposite response trends of SIF confirm the mechanism of PSI herbicides in photosynthetic injury. Finally, the sensitivity of SIF signals were compared to other vegetation indices, and the Fr688/760 ratio turned out to be a sensitive tool to rapidly detect herbicide injury.