Journal Article

FZJ-2024-06603

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Comparing methods for solar-induced fluorescence efficiency estimation using radiative transfer modelling and airborne diurnal measurements of barley crops

Bendig, J. (Corresponding author)FZJ* ; Malenovský, Z. ; Siegmann, B.FZJ* ; Krämer, J.FZJ* ; Rascher, U.FZJ*

2025
Elsevier Science Amsterdam [u.a.]

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Please use a persistent id in citations: doi:10.1016/j.rse.2024.114521  doi:10.34734/FZJ-2024-06603

Abstract: Ability of remotely sensed solar-induced chlorophyll fluorescence (SIF) to serve as a vegetation productivity andstress indicator is impaired by confounding factors, such as varying crop-specific canopy structure, changingsolar illumination angles, and SIF-soil optical interactions. This study investigates two normalisation approachescorrecting diurnal top-of-canopy SIF observations retrieved from the O2-A absorption feature at 760 nm (F760hereafter) of summer barley crops for these confounding effects. Nadir SIF data was acquired over nine breedingexperimental plots simultaneously by an airborne imaging spectrometer (HyPlant) and a drone-based high-performance point spectrometer (AirSIF). Ancillary measurements, including leaf pigment contents retrievedfrom drone hyperspectral imagery, destructively sampled leaf area index (LAI), and leaf water and dry mattercontents, were used to test the two normalisation methods that are based on: i) the fluorescence correctionvegetation index (FCVI), and ii) three versions of the near-infrared reflectance of vegetation (NIRV). Modelling inthe discrete anisotropic radiative transfer (DART) model revealed close matches for NIRv-based approacheswhen corrected canopy SIF was compared to simulated total chlorophyll fluorescence emitted by leaves (R2 =0.99). Normalisation with the FCVI also performed acceptably (R2 = 0.93), however, it was sensitive to varia-tions in LAI when compared to leaf emitted chlorophyll fluorescence efficiency. Based on the results modelled inDART, the NIRvH1 normalisation was found to have a superior performance over the other NIRv variations andthe FCVI normalisation. Comparison of the SIF escape fractions suggests that the escape fraction estimated withNIRvH1 matched escape fraction extracted from DART more closely. When applied to the experimental droneand airborne nadir canopy SIF data, the agreement between NIRvH1 and FCVI produced chlorophyll fluores-cence efficiency was very high (R2 = 0.93). Nevertheless, NIRvH1 showed higher uncertainties for areas with lowvegetation cover indicating an unaccounted contribution of SIF-soil interactions. The diurnal courses of chlo-rophyll fluorescence efficiency for both approaches differed not significantly from simple normalisation byincoming and apparent photosynthetically active radiation. In conclusion, SIF normalisation with NIRvH1 moreaccurately compensates the effects of canopy structure on top of canopy far red SIF, but when applied to top ofcanopy in-situ data of spring barley, the effects of NIRvH1 and FCVI on the diurnal course of SIF had a similarinfluence.

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Contributing Institute(s):

1. Pflanzenwissenschaften (IBG-2)

Research Program(s):

1. 2173 - Agro-biogeosystems: controls, feedbacks and impact (POF4-217) (POF4-217)
2. DFG project G:(GEPRIS)491111487 - Open-Access-Publikationskosten / 2022 - 2024 / Forschungszentrum Jülich (OAPKFZJ) (491111487) (491111487)

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Database coverage:
; ; ; BIOSIS Previews ; Biological Abstracts ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF >= 10 ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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