Stress-induced changes in photosynthesis and proximal fluorescence emission of turfgrass

Remote measurements of solar-induced fluorescence (SIF) are now widely used to model gross primary productivity (GPP). However, the ability of SIF to track GPP in different environments, conditions, and at different scales remains uncertain. We designed an experiment to measure SIF and photosynthesis while inducing plant stress in replicated turfgrass. Immediately following application of abscisic acid (ABA), treated grasses experienced a 75% decrease in photosynthesis and an 18% decline in SIFyield, with evidence of alterations in energy partitioning. Withholding water resulted in slower photosynthetic inhibition of lower magnitude, with full recovery upon rewatering. In both treatments, reductions in SIF co-occurred with reductions in canopy greenness. However, we did not observe a relationship between the SIF and near-infrared reflectance of vegetation (NIRv) responses to our treatments in turfgrass. The response differences between treatments highlight the nuances of using SIF as a proxy for GPP.