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Title: Circadian rhythms have significant effects on leaf-to-canopy scale gas exchange under field conditions

Background Molecular clocks drive oscillations in leaf photosynthesis, stomatal conductance, and other cell and leaf-level processes over ~24 h under controlled laboratory conditions. The influence of such circadian regulation over whole-canopy fluxes remains uncertain; diurnal CO 2 and H 2O vapor flux dynamics in the field are currently interpreted as resulting almost exclusively from direct physiological responses to variations in light, temperature and other environmental factors. We tested whether circadian regulation would affect plant and canopy gas exchange at the Montpellier European Ecotron. Canopy and leaf-level fluxes were constantly monitored under field-like environmental conditions, and under constant environmental conditions (no variation in temperature, radiation, or other environmental cues). Results We show direct experimental evidence at canopy scales of the circadian regulation of daytime gas exchange: 20–79 % of the daily variation range in CO 2 and H 2O fluxes occurred under circadian entrainment in canopies of an annual herb (bean) and of a perennial shrub (cotton). We also observed that considering circadian regulation improved performance by 8–17 % in commonly used stomatal conductance models. Conclusions Our results show that circadian controls affect diurnal CO 2 and H 2O flux patterns in entire canopies in field-like conditions, and its consideration significantlymore » improves model performance. Lastly, circadian controls act as a ‘memory’ of the past conditions experienced by the plant, which synchronizes metabolism across entire plant canopies.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [1] ;  [6] ;  [7] ;  [8] ;  [6] ;  [1] ;  [9] ;  [6] ;  [10] ;  [11] ;  [12] ;  [13] ;  [13] ;  [1] ;  [6]
  1. Univ. de Lleida (Spain). Dept. of Crop and Forest Sciences Agrotecnico Center
  2. Swiss Federal Inst. for Forest, Snow and Landscape Research, Long-term Forest Ecosystem Research, Birmensdorf (Switzerland); Leibniz Centre for Agricultural Landscape Research, Muncheberg (Germany)
  3. Univ. de Lleida (Spain). Dept. of Crop and Forest Sciences Agrotecnico Center; Univ. de Concepcion, Concepcion (Chile). Dept. de Botanica
  4. Univ. de Lleida (Spain). Dept. of Crop and Forest Sciences Agrotecnico Center; Univ. of Liverpool (United Kingdom). School of Environmental Sciences
  5. Univ. of Innsbruck, Innsbruck (Austria). Inst. of Ecology
  6. Centre National de la Recherche Scientifique (CNRS), Montferrier-sur-Lez (France). Ecotron Europeen de Montpellier
  7. Madrid Inst. for Research and Rural Development, Agrarian and Food, Farm 'El Encin', Madrid (Spain)
  8. Leibniz Centre for Agricultural Landscape Research, Muncheberg (Germany); US Dept. of Agriculture (USDA)., Livermore, CA (United States). Forest Service, Northern Research Station ; Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  9. Centre National de la Recherche Scientifique (CNRS), Montferrier-sur-Lez (France). Ecotron Europeen de Montpellier; Univ. de Montpellier (France)
  10. Leibniz Centre for Agricultural Landscape Research, Muncheberg (Germany); Freie Univ., Berlin (Germany). Inst. fur Biologie, Plant Ecology; Berlin-Brandenburg Inst. of Advanced Biodiversity Research, Berlin (Germany)
  11. Centre National de la Recherche Scientifique (CNRS), Montferrier-sur-Lez (France). Ecotron Europeen de Montpellie
  12. Univ. de Lleida (Spain). Erasmus Mundus Master on Mediterranean Forestry and Natural Resources Management; Univ. of Canterbury, Christchurch (New Zealand). School of Forestry, College of Engineering
  13. Western Sydney Univ., Richmond, NSW (Australia). Hawkesbury Inst. for the Environment
Publication Date:
Grant/Contract Number:
AC52-07NA27344; ANR-11-INBS-0001; NA; RYC-2012-10970; RYC-2008-02050; AGL2015-69151-R
Type:
Accepted Manuscript
Journal Name:
GigaScience
Additional Journal Information:
Journal Volume: 5; Journal Issue: 1; Journal ID: ISSN 2047-217X
Publisher:
BioMed Central
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 59 BASIC BIOLOGICAL SCIENCES; Circadian clock; Ecological memory; Net ecosystem exchange; Scaling, Stomatal conductance models; Photosynthesis; Transpiration
OSTI Identifier:
1395308