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Testing a vapour‐phase model of stomatal responses to humidity
Author(s) -
MOTT KEITH A.,
PEAK DAVID
Publication year - 2013
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12026
Subject(s) - guard cell , humidity , water vapor , conductance , botany , horticulture , chemistry , thermodynamics , environmental science , biology , mathematics , physics , organic chemistry , combinatorics
This study tests two predictions from a recently proposed model for stomatal responses to humidity and temperature. The model is based on water potential equilibrium between the guard cells and the air at the bottom of the stomatal pore and contains three independent variables: g s 0 , Z and Θ . g s 0 is the value of stomatal conductance that would occur at saturating humidity and will vary among leaves and with CO 2 and light. The value of Z is determined primarily by the resistance to heat transfer from the epidermis to the evaporating site and the value of Θ is determined primarily by the resistance to water vapour diffusion from the evaporating site to the guard cells. This leads to the two predictions that were tested. Firstly, the values of Z and Θ should be constant for leaves of a given species grown under given conditions, although g s 0 should vary among leaves and with light and CO 2 . And secondly, the ratio of Z to Θ should be higher in leaves having their stomata in crypts because the distance for heat transfer is greater than that for water vapour diffusion. Data from three species, Nerium oleander , Pastinaca sativum and Xanthium strumarium support these two predictions.