TY - JOUR T1 - Circadian rhythms have significant effects on leaf-to-canopy gas exchange under field conditions JF - bioRxiv DO - 10.1101/054593 SP - 054593 AU - Víctor Resco de Dios AU - Arthur Gessler AU - Juan Pedro Ferrio AU - Josu G Alday AU - Michael Bahn AU - Jorge del Castillo AU - Sébastien Devidal AU - Sonia García-Muñoz AU - Zachary Kayler AU - Damien Landais AU - Paula Martín AU - Alexandru Milcu AU - Clément Piel AU - Karin Pirhofer-Walzl AU - Olivier Ravel AU - Serajis Salekin AU - David T Tissue AU - Mark G Tjoelker AU - Jordi Voltas AU - Jacques Roy Y1 - 2016/01/01 UR - http://biorxiv.org/content/early/2016/05/21/054593.abstract N2 - 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 and diurnal CO2 and H2O 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 CNRS Ecotron. Canopy and leaf level fluxes were constantly monitored under field-like environmental conditions, and also under constant environmental conditions (no variation in temperature, radiation or other environmental cues). Here we show first direct experimental evidence at canopy scales of circadian gas exchange regulation: 20-79% of the daily variation range in CO2 and H2O 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 in commonly used stomatal conductance models. Overall, our results show that overlooked circadian controls affect diurnal patterns of CO2 and H2O fluxes in entire canopies and in field-like conditions, although this process is currently unaccounted for in models. ER -