Intermediate Aerosol Loading Enhances Photosynthetic Activity of Croplands

Abstract

Aerosols can affect crop photosynthesis by altering radiation and meteorological conditions. By combining field observations, mechanistic modeling, and satellite-retrieved solar-induced chlorophyll fluorescence (SIF), we assessed aerosols' impacts on crop photosynthesis from leaf to regional scale. We found that the initial increase in aerosol optical depth (AOD) enhanced photosynthesis of sun leaves, shade leaves, and canopy, which reached their maximum at AOD = 0.76, 1.13, and 0.93, respectively, and then decreased. Aerosol-induced changes in radiation regime and the concurrent high relative humidity led to such nonlinear responses. Similarly, the SIF of croplands in the North China Plain (NCP) also showed a bell-shaped response to aerosols. The optimal AOD level at which SIF reached the maximum value varied from 0.56 to 1.04, depending on the background meteorological conditions. Approximately 76%–90% of the NCP exceeded the optimal AOD level, suggesting that stringent aerosol pollution control could promote cropland productivity in this region.