Exploring the Sensitivity of Solar-Induced Chlorophyll Fluorescence at Different Wavelengths in Response to Drought

Due to the mechanistic coupling between solar-induced chlorophyll fluorescence (SIF) and photosynthesis, SIF has an advantage over greenness-based vegetation indices in detecting drought. Since photosystem I (PSI) contributes very little red SIF, is assumed be more responsive environmental stress than far-red SIF. However, addition affecting drought also impact on concentration thus affects reabsorption process of When these responses are entangled, sensitivity regions response not yet clear. In this study, we conducted a water experiment maize field measured upward downward leaf spectra by spectrometer assembled with clip. Simultaneously, leaf-level active was pulse-amplified modulation (PAM) fluorometer. We found that after normalization photosynthetically radiation (PAR) dark-adapted minimal (Fo), better estimation yield. By comparing wavelength-dependent link yield nonphotochemical quenching (NPQ) across range 660 800 nm, results show have different sensitivities region strong stable correlation NPQ. Drought only reduces due photosynthetic regulation, but it increases reducing content (weakening effect). The co-existence two contradictory effects makes level unable reliably indicate addition, red:far-red ratio at peak can good indicators content. These findings help interpret variations remote sensing techniques fully exploit information when monitoring plant stress.