title: Sun-induced chlorophyll fluorescence from high-resolution imaging spectroscopy data to quantify spatio-temporal patterns of photosynthetic function in crop canopies.
abstract: Passive detection of sun-induced chlorophyll fluorescence (SIF) using spectroscopy has been proposed as a proxy to quantify changes in photochemical efficiency at canopy level under natural light conditions. In this study, we explored the use of imaging spectroscopy to quantify spatio-temporal dynamics of SIF within crop canopies and its sensitivity to track patterns of photosynthetic activity originating from the interaction between vegetation structure and incoming radiation as well as variations in plant function. SIF was retrieved using the Fraunhofer Line Depth (FLD) principle from imaging spectroscopy data acquired at different time scales a few metres above several crop canopies growing under natural illumination. We report the first maps of canopy SIF in high spatial resolution. Changes of SIF were monitored at different time scales ranging from quick variations under induced stress conditions to seasonal dynamics. Natural changes were primarily determined by varying levels and distribution of photosynthetic active radiation (PAR). However, this relationship changed throughout the day demonstrating an additional physiological component modulating spatio-temporal patterns of SIF emission. We successfully used detailed SIF maps to track changes in the canopy's photochemical activity under field conditions, providing a new tool to evaluate complex patterns of photosynthesis within the canopy.
authors.affiliation: Institute of Bio- and Geosciences, IBG-2: Plant Sciences, Forschungszentrum Jülich GmbH, 52428, Jülich, Germany.
authors.forename: Francisco
authors.initials: F
authors.lastname: Pinto
authors.affiliation: Remote Sensing Laboratories, Department of Geography, University of Zurich, 8057, Zürich, Switzerland.
authors.forename: Alexander
authors.initials: A
authors.lastname: Damm
authors.affiliation: Institute of Bio- and Geosciences, IBG-2: Plant Sciences, Forschungszentrum Jülich GmbH, 52428, Jülich, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Schickling
authors.affiliation: Remote Sensing of Environmental Dynamics Laboratory, Department of Earth and Environmental Science (DISAT), University of Milano-Bicocca, 20126, Milan, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Panigada
authors.affiliation: Remote Sensing of Environmental Dynamics Laboratory, Department of Earth and Environmental Science (DISAT), University of Milano-Bicocca, 20126, Milan, Italy.
authors.forename: Sergio
authors.initials: S
authors.lastname: Cogliati
authors.affiliation: Institute of Bio- and Geosciences, IBG-2: Plant Sciences, Forschungszentrum Jülich GmbH, 52428, Jülich, Germany.
authors.forename: Mark
authors.initials: M
authors.lastname: Müller-Linow
authors.affiliation: INRES-Plant Breeding, University of Bonn, 53115, Bonn, Germany.|Experimental Station of University of Bonn in Klein-Altendorf, 53359, Rheinbach, Germany.
authors.forename: Agim
authors.initials: A
authors.lastname: Balvora
authors.affiliation: Institute of Bio- and Geosciences, IBG-2: Plant Sciences, Forschungszentrum Jülich GmbH, 52428, Jülich, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Rascher
mesh_terms: D002734:Chlorophyll / Q000032:analysis*; D018556:Crops, Agricultural / Q000378:metabolism*; D004237:Diuron; D010788:Photosynthesis; D012621:Seasons; D013050:Spectrometry, Fluorescence / Q000379:methods*; D014908:Triticum; D003313:Zea mays
chemical_list: D002734:Chlorophyll; D004237:Diuron
keywords: PAR (photosynthetic active radiation); canopy photochemical efficiency; dynamic photoinhibition; imaging spectroscopy; remote sensing of vegetation; sun-induced chlorophyll fluorescence; top-of-canopy irradiance dynamics