Solar-induced chlorophyll fluorescence captures the effects of elevated ozone on canopy structure and acceleration of senescence in soybean

Authors: WU, GENGHONG - University Of Illinois; GUAN, KAIYU - University Of Illinois; Ainsworth, Elizabeth - Lisa; MARTIN, DUNCAN - University Of Illinois; KIMM, HYUNGSUK - Seoul National University; YANG, XI - University Of Virginia

Submitted to: Journal of Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2023
Publication Date: 9/13/2023
Citation: Wu, G., Guan, K., Ainsworth, E.A., Martin, D.G., Kimm, H., Yang, X. 2023. Solar-induced chlorophyll fluorescence captures the effects of elevated ozone on canopy structure and acceleration of senescence in soybean. Journal of Experimental Botany. 75(1):350-363. https://doi.org/10.1093/jxb/erad356.
DOI: https://doi.org/10.1093/jxb/erad356

Interpretive Summary: Solar-induced chlorophyll fluorescence (SIF) provides a new opportunity for rapid and noninvasive quantification of physiological and structural properties that are important to crop productivity. SIF is an optical signal emitted by plants after absorbing sunlight and is functionally linked to photosynthesis and plant canopy properties. This study tested the potential for SIF to identify changes in soybean structure and physiology after exposure to ozone stress. Ozone is a damaging air pollutant that is well-known to decrease photosynthesis, accelerate senescence, and reduce yields. We found that SIF was significantly decreased by elevated ozone, especially late in the growing season, consistent with accelerated senescence. Decomposing the SIF signal into canopy structural and physiological components showed that the structural component was more consistently impacted by ozone, consistent with the large decrease in leaf area index. This study provides evidence that SIF could be a new phenotyping tool for identifying ozone damage to crops.

Technical Abstract: Solar-induced chlorophyll fluorescence (SIF) provides an opportunity to rapidly and non-destructively investigate how plants respond to stress. Here, we explored the potential of SIF to evaluate elevated O3 effects on soybean in the field where soybean was subjected to ambient and elevated O3 throughout the growing season in 2021. Exposure to elevated O3 resulted in a significant decrease in canopy SIF at 760 nm (SIF760), with a larger decrease at a late growth stage (36%) compared to earlier stages (13%). Elevated O3 significantly decreased the fraction of absorbed photosynthetic active radiation by 15% at earlier stages, and by 35% at the late growth stage. SIF760 escape ratio (fesc) was significantly increased under elevated O3 by 5-12% in the late growth stage due to decreased chlorophyll content and leaf area index. These results demonstrated that SIF could capture the effects of elevated O3 on canopy structure and acceleration of senescence, providing empirical support for using SIF for soybean stress detection and phenotyping.