Generalized hydromechanical model for stomatal responses to hydraulic perturbations.
Stomata respond in a common pattern to various hydraulic perturbations on any part of the 'soil-plant-air' system: initial transient 'wrong-way' responses and final stationary 'right-way' responses. In order to describe this pattern on the basis of statistical physics, we propose a simple model where turgor pressure of a cell is taken to be a power function of its volume, and obtain results in qualitative agreement with experimental data for responses to a variety of hydraulic perturbations: Firstly, stationary stomatal conductance as a function of the vapor pressure deficit divides into three regimes characterized by sensitivities of the stomatal conductance and the transpiration rate with respect to vapor pressure deficit; secondly, for every hydraulic perturbation, the initial transient 'wrong-way' responses always appear; thirdly, on condition that water is supplied insufficiently, stomatal oscillations are often observed; finally, stomatal responses following leaf excision exhibit, after the initial transient wrong-way responses, slow relaxation to stomatal closing. In particular, comparison of areoles having different numbers of stomata demonstrates that areoles with small numbers of stomata tend to provoke lack of water in the soil as well as in the plant. In addition, our model also describes well dependence of the stomatal conductance on temperature. It may be extended further to describe stomatal responses to other environmental factors such as carbon dioxide, light, and temperature.
Department of Physics and Astronomy and Center for Theoretical Physics, Seoul National University, Seoul 151-747, Republic of Korea; School of Physics, Korea Institute for Advanced Study, Seoul 130-722, Republic of Korea.
H W
HW
Kwon
M Y
MY
Choi
D000388:Air; D002245:Carbon Dioxide / Q000737:chemistry; D002473:Cell Wall / Q000378:metabolism; D008027:Light; D008031:Lignin / Q000737:chemistry; D008564:Membrane Potentials; D008954:Models, Biological; D010539:Permeability; D010788:Photosynthesis; D018515:Plant Leaves / Q000378:metabolism / Q000502:physiology*; D054046:Plant Stomata / Q000502:physiology*; D018526:Plant Transpiration; D011312:Pressure; D012987:Soil; D013696:Temperature; D014867:Water / Q000737:chemistry / Q000378:metabolism; D052584:Xylem / Q000378:metabolism
D012987:Soil; D014867:Water; D002245:Carbon Dioxide; D008031:Lignin
Cavitation; Conductance; Leaf excision; Transpiration; Wrong-way response