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Stomatal responses to humidity in air and helox

Stomatal responses to humidity in air and helox Abstract. Stomatal responses to humidity were studied in several species using normal air and a helium: oxygen mixture (79:21 v/v, with CO2 and water vapour added), which we termed ‘helox’. Since water vapour diffuses 2.33 times faster in helox than in air, it was possible to vary the water‐vapour concentration difference between the leaf and the air at the leaf surface independently of the transpiration rate and vice versa. The CO2 concentration at the evaporating surfaces (ci), leaf temperature and photon flux density were kept constant throughout the experiments. The results of these experiments were consistent with a mechanism for Stomatal responses to humidity that is based on the rate of water loss from the leaf. Stomata apparently did not directly sense and respond to either the water vapour concentration at the leaf surface or the difference in water vapour concentration between the leaf interior and the leaf surface. In addition, stomatal responses that caused reductions in transpiration rate at low humidities were accompanied by decreases in photosynthesis at constant ci, suggesting heterogeneous (patchy) stomatal closure. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Plant Cell & Environment Wiley

Stomatal responses to humidity in air and helox

Plant Cell & Environment , Volume 14 (5) – Jun 1, 1991

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References (21)

Publisher
Wiley
Copyright
Copyright © 1991 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0140-7791
eISSN
1365-3040
DOI
10.1111/j.1365-3040.1991.tb01521.x
Publisher site
See Article on Publisher Site

Abstract

Abstract. Stomatal responses to humidity were studied in several species using normal air and a helium: oxygen mixture (79:21 v/v, with CO2 and water vapour added), which we termed ‘helox’. Since water vapour diffuses 2.33 times faster in helox than in air, it was possible to vary the water‐vapour concentration difference between the leaf and the air at the leaf surface independently of the transpiration rate and vice versa. The CO2 concentration at the evaporating surfaces (ci), leaf temperature and photon flux density were kept constant throughout the experiments. The results of these experiments were consistent with a mechanism for Stomatal responses to humidity that is based on the rate of water loss from the leaf. Stomata apparently did not directly sense and respond to either the water vapour concentration at the leaf surface or the difference in water vapour concentration between the leaf interior and the leaf surface. In addition, stomatal responses that caused reductions in transpiration rate at low humidities were accompanied by decreases in photosynthesis at constant ci, suggesting heterogeneous (patchy) stomatal closure.

Journal

Plant Cell & EnvironmentWiley

Published: Jun 1, 1991

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