Physiological dynamics dominate the response of canopy far-red solar-induced fluorescence to herbicide treatment

•The physiological and non-physiological dynamics of SIF under herbicide stress are quantified.•SIF captures herbicide-induced photosynthetic anomalies in heterogeneous cropland ecosystems.•SIF, NIRv and GPP have different responses to herbicide stress.•The link between SIF and GPP was disturbed after herbicide treatment.•ΦF dominates the variation of SIF in the early stage after herbicide treatment.