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@INPROCEEDINGS{Rossini:190161,
      author       = {Rossini, Micol and Alberti, Giorgio and Bozzi, Emiliano and
                      Celesti, Marco and Cilia, Chiara and Cogliati, Sergio and
                      Colombo, Roberto and Julitta, Tommaso and Juszczak,
                      Radosław and Miglietta, Franco and Panigada, Cinzia and
                      Pinto, Francisco and Sakowska, Karolina and Schickling, Anke
                      and Schuettemeyer, Dirk and Stróżecki, Marcin and
                      Tudoroiu, Marin and Rascher, Uwe},
      title        = {{M}onitoring the evolution of plant photosynthetic
                      performances using ground sun-induced fluorescence
                      measurements},
      reportid     = {FZJ-2015-03092},
      year         = {2015},
      abstract     = {Plants subjected to biotic or abiotic stress factors can
                      respond with adjustments in their biochemical and
                      physiological processes. These adjustments are often
                      accompanied by changes in reflectance, transmittance, and
                      absorbance at leaf and canopy level.This contribution aims
                      to understand how optical signals linked to plant physiology
                      changes after the application of two different chemical
                      agents: an herbicide blocking the electron-transfer
                      mechanisms in the photosynthetic apparatus (Chlortoluron)
                      and an anti-transpirant chemical known to reduce plant
                      transpiration (Vapor Gard) by sealing the stomata. The
                      chemicals have been applied on 9 grass plots with different
                      concentrations. Three plots have been kept not-treated and
                      used as control. Canopy high resolution spectral
                      measurements and CO2 fluxes have been collected daily on the
                      same sampling area in each plot for the entire duration of
                      the experiment to monitor the temporal evolution of the
                      stress effects.Spectral measurements have been used to
                      estimate the sun-induced chlorophyll fluorescence in both
                      the red (SIF687) and far-red region (SIF760), the
                      Photochemical Reflectance Index (PRI) linked to the
                      xanthophyll-related heat dissipation and several traditional
                      vegetation indices related to canopy greenness and
                      chlorophyll concentration. SIF687 and SIF760 were estimated
                      with spectral fitting methods spectrally modeling the
                      radiance collected with very high resolution spectrometers
                      in the oxygen absorption O2-A and O2-B bands.The applied
                      treatments induced a variation of plant photosynthetic
                      functioning modulated according to the level of herbicide
                      concentration. Both SIF687 and SIF760 measured in
                      Chlortoluron-treated grass plots were significantly higher
                      than in the control plots. The highest dose caused
                      fluorescence values to double in less than 3 hours while the
                      reflectance signal at the same time was not affected
                      confirming that the increase in fluorescence emission was
                      only related to variations in the plant functional status
                      not associated to changes in pigment content and
                      composition. F687 and F760 values of treated plots decreased
                      steeply in the following days. Fluorescence decline was
                      accompanied by a decrease in chlorophyll content. Grass
                      photosynthesis began to decline immediately after the
                      herbicide application and continued in the following days.
                      This result implies that fluorescence was negatively
                      correlated to plant photosynthesis in an early phase of
                      stress reaction and then the relation became positive in the
                      following days. Thus the translation of fluorescence values
                      to photosynthesis is not straightforward in this experiment.
                      Lower doses affected fluorescence signal similarly but with
                      a different temporal dynamic in both the initial rise and
                      the recovery. Chlortoluron also caused an initial increase
                      of PRI values followed by a gradual decline associated to
                      the degradation of the pigment pool. The application of the
                      anti-transpirant agent only slightly affected fluorescence
                      emission and PRI probably because the photosynthetic system
                      was not directly compromised.Sun-induced chlorophyll
                      fluorescence allowed to monitor the temporal dynamics of
                      plants’ functioning and recovery after the application of
                      temporarily blocking photosynthesis agents. Further studies
                      are ongoing to better understand the effects of stress on
                      the fluorescence signal and the link to heat dissipation and
                      photosynthesis.},
      month         = {Apr},
      date          = {2015-04-14},
      organization  = {9th EARSel Imaging Spectroscopy
                       Workshop, Luxembourg (Luxembourg), 14
                       Apr 2015 - 16 Apr 2015},
      subtyp        = {After Call},
      cin          = {IBG-2},
      cid          = {I:(DE-Juel1)IBG-2-20101118},
      pnm          = {582 - Plant Science (POF3-582)},
      pid          = {G:(DE-HGF)POF3-582},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/190161},
}