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Analysis of stomatal CO 2 uptake by a three‐dimensional cylindrically symmetric model
Author(s) -
VESALA T.,
AHONEN T.,
HARI P.,
KRISSINEL E.,
SHOKHIREV N.
Publication year - 1996
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1996.tb01843.x
Subject(s) - carbon dioxide , photosynthesis , photorespiration , sink (geography) , diffusion , thermal diffusivity , fick's laws of diffusion , flux (metallurgy) , respiration , chemistry , thermodynamics , physics , botany , biology , cartography , organic chemistry , geography
summary 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 alone with y 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 flux density and the chlorophyll concentration. 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 differences between hypostomatous and needle‐like leaves are analysed with special attention. To vield 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 mesophyllic 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.