Stomatal CO2 uptake by a three-dimensional cylindrically symmetric model



Analysis of stomatal CO2 uptake by a three-dimensional cylindrically symmetric model

by Vesala T., Ahonen T., Hari P., Krissinel E., Shokirev N. (1996)

^Department of Physics, P.O. Box 9, FIN-000J4, University of Helsinki, Finland

^Department of Forest Ecology, P.O. Box 24, FIN-00014, University of Helsinki, Finland

‘^Russian Academy of Sciences, Institute for Water and Environmental Problems, Papanintsev 105, Barnaul 656099, Russia

* Russian Academy of Sciences, Institute of Chemical Kinetics and Combustion, Institutskaya 3, Novosibirsk 630090, Russia

in New Phytologist 1996, 132: 235-245 –

Google Scholar CrossRef


A numerical model is introduced that solves the steady-state diffusion equation for a single stoma and the mesophyll surrounding- This system has cylindrical symmetry, and diffusive transport of carbon dioxide in the gas phase is coupled with transfer in mesophyll along with a photosynthetic sink rate and respiratory production rates.

The mesophyll is treated as a continuously distributed liquid phase, and the photosynthetic rate is determined by the carbon dioxide concentration, the photosynthetic photon fiux density and the chlorophyll concenfration.

Photorespiration is proportional to the photon flux density, and dark respiration is assumed to be constant. The model offers a rigorous way to investigate the roles of physics and geometrical structure in stomatal gas exchange.

Lateral (radial) diffusion and diflerences between hypostomatous and needle-like leaves are analysed with special attention. To yield realistic stomatal behaviour, the model requires that the diffusion coefficient describing mesophyllic transport must be somewhat larger than carbon dioxide diffusivity in pure liquid water. The mesophyilic carbon dioxide concentration slopes sharply towards a constant value as a function of distance from the surface of a sub-stomatal cavity. The optimal placement of chlorophyll is close to the surface containing stomata.



Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.

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