title: O2dynamics in the rhizosphere of young rice plants (Oryza sativaL.) as studied by planar optodes.
abstract: OBJECTIVE
  Radial O2loss (ROL) strongly affect the O2availability in the rhizosphere of rice. The ROL create an oxic zone around the roots, protecting the plant from toxic reduced chemical species and regulates the redox chemistry in the soil. This study investigates the spatio-temporal variability in O2dynamics in the rice rhizosphere.
  
  
  METHODS
  Applying high-resolution planar optode imaging, we investigated the O2dynamics of plants grown in water saturated soil, as a function of ambient O2level, irradiance and plant development, for submerged and emerged plants.
  
  
  RESULTS
  O2leakage was heterogeneously distributed with zones of intense leakage around roots tips and young developing roots. While the majority of roots exhibited high ROL others remained surrounded by anoxic soil. ROL was affected by ambient O2levels around the plant, as well as irradiance, indicating a direct influence of photosynthetic activity on ROL. At onset of darkness, oxia in the rhizosphere was drastically reduced, but subsequently oxia gradually increased, presumably as root and/or soil respiration declined.
  
  
  CONCLUSIONS
  The study demonstrates a high spatio-temporal heterogeneity in rhizosphere O2dynamics and difference in ROL between different parts of the rhizosphere. The work documents that spatio-temporal measurements are important to fully understand and account for the highly variable O2dynamics and associated biogeochemical processes and pathways in the rice rhizosphere.
authors.affiliation: Institute of Biology and Nordic Center for Earth Evolution (NordCEE), University of Southern Denmark, 5320 Odense M, Denmark.|Scottish Marine Institute, Scottish Association for Marine Science, Oban, Scotland PA37 1QA UK.|Greenland Climate Research Centre (CO Greenland Institute of National resources), Kivioq 2, Box 570, 3900 Nuuk, Greenland.
authors.forename: Morten
authors.initials: M
authors.lastname: Larsen
authors.affiliation: Rhizosphere Ecology and Biogeochemistry Group, Institute of Soil Science, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences Vienna, 3430 Tulln, Austria.
authors.forename: Jakob
authors.initials: J
authors.lastname: Santner
authors.affiliation: Rhizosphere Ecology and Biogeochemistry Group, Institute of Soil Science, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences Vienna, 3430 Tulln, Austria.
authors.forename: Eva
authors.initials: E
authors.lastname: Oburger
authors.affiliation: Rhizosphere Ecology and Biogeochemistry Group, Institute of Soil Science, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences Vienna, 3430 Tulln, Austria.
authors.forename: Walter W
authors.initials: WW
authors.lastname: Wenzel
authors.affiliation: Institute of Biology and Nordic Center for Earth Evolution (NordCEE), University of Southern Denmark, 5320 Odense M, Denmark.|Scottish Marine Institute, Scottish Association for Marine Science, Oban, Scotland PA37 1QA UK.|Greenland Climate Research Centre (CO Greenland Institute of National resources), Kivioq 2, Box 570, 3900 Nuuk, Greenland.|Arctic Research Centre, Aarhus University, 8000 Aarhus, Denmark.
authors.forename: Ronnie N
authors.initials: RN
authors.lastname: Glud
keywords: Oxygen; Planar optode; Plaques imaging; Radial oxygen loss; Rhizosphere; Rice (Oryza sativa L.)