Attributing differences of solar-induced chlorophyll fluorescence (SIF)-gross primary production (GPP) relationships between two C4 crops: corn and miscanthus

Authors: WU, GENGHONG - University Of Illinois; GUAN, KAIYU - University Of Illinois; JIANG, CHONGYA - University Of Illinois; KIMM, HYUNGSUK - University Of Illinois; MIAO, GUOFANG - University Of Illinois; Bernacchi, Carl; MOORE, CAITLIN - University Of Western Australia; Ainsworth, Elizabeth - Lisa; YANG, XI - University Of Virginia; BERRY, JOSEPH - Carnegie Institute - Stanford; FRANKENBERG, CHRISTIAN - California Institute Of Technology; CHEN, MIN - University Of Wisconsin

Submitted to: Agricultural and Forest Meteorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2022
Publication Date: 6/21/2022
Citation: Wu, G., Guan, K., Jiang, C., Kimm, H., Miao, G., Bernacchi, C.J., Moore, C.E., Ainsworth, E.A., Yang, X., Berry, J.A., Frankenberg, C., Chen, M. 2022. Attributing differences of solar-induced chlorophyll fluorescence (SIF)-gross primary production (GPP) relationships between two C4 crops: corn and miscanthus. Agricultural and Forest Meteorology. 323. Article 109046. https://doi.org/10.1016/j.agrformet.2022.109046.
DOI: https://doi.org/10.1016/j.agrformet.2022.109046

Interpretive Summary: Through the absorption of light from the sun, plants are able to perform photosynthesis which drives growth and, importantly, yields of crops that are the basis of food production. Some of the absorbed sunlight is given off by plants in a process named Solar Induced Fluorescence (SIF). Because SIF is linked with light absorption, there is the possibility to link measurements of SIF with how much photosynthesis is occurring at the whole plant-canopy (combination of all leaves and their arrangement). Many studies have looked at how different crops vary in the relationship with SIF and plant-canopy photosynthesis, but different types of photosynthesis, leaf physiology, and plant-canopy architectures make inferring differences difficult. In this study, two crops using the same type of photosynthesis but with different leaf physiologies and plant-canopy architectures were measured using both SIF and GPP measurements. The results from this research showed that despite very similar photosynthetic mechanisms, two crops had significant differences in the relationship between SIF and plant-canopy photosynthesis, and these differences were attributed primarily to differences in leaf physiology. The results are an important step toward using SIF, which can be done using aircraft or satellites, to understand real-time differences in photosynthesis for different crops.

Technical Abstract: There remains limited information to characterize the solar-induced chlorophyll fluorescence (SIF)-gross primary production (GPP) relationship in C4 cropping systems. The annual C4 crop corn and perennial C4 crop miscanthus differ in phenology, canopy structure and leaf physiology. Investigating the SIF-GPP relationships in these species could deepen our understanding of SIF-GPP relationships within C4 crops. Using in situ canopy SIF and GPP measurements for both species along with leaf-level measurements, we found considerable differences in the SIF-GPP relationships between corn and miscanthus, with a stronger SIF-GPP relationship and higher slope of SIF-GPP observed in corn compared to miscanthus. These differences were mainly caused by leaf physiology. For miscanthus, high non-photochemical quenching (NPQ) under high light, temperature and water vapor deficit (VPD) conditions caused a large decline of fluorescence yield (FF), which further led to a SIF midday depression and weakened the SIF-GPP relationship. The larger slope in corn than miscanthus was mainly due to its higher GPP in mid-summer, largely attributed to the higher leaf photosynthesis and less NPQ. Our results demonstrated variation of the SIF-GPP relationship within C4 crops and highlighted the importance of leaf physiology in determining canopy SIF behaviors and SIF-GPP relationships.