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How do leaf hydraulics limit stomatal conductance at high water vapour pressure deficits

Permanent URL:
http://handle.nal.usda.gov/10113/32398
File:
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Abstract:
A reduction in leaf stomatal conductance (g) with increasing leaf-to-air difference in water vapour pressure (D) is nearly ubiquitous. Ecological comparisons of sensitivity have led to the hypothesis that the reduction in g with increasing D serves to maintain leaf water potentials above those that would cause loss of hydraulic conductance. A reduction in leaf water potential is commonly hypothesized to cause stomatal closure at high D. The importance of these particular hydraulic factors was tested by exposing Abutilon theophrasti, Glycine max, Gossypium hirsutum and Xanthium strumarium to D high enough to reduce g and then decreasing ambient carbon dioxide concentration ([CO₂]), and observing the resulting changes in g, transpiration rate and leaf water potential, and their reversibility. Reducing the [CO₂] at high D increased g and transpiration rate and lowered leaf water potential. The abnormally high transpiration rates did not result in reductions in hydraulic conductance. Results indicate that low water potential effects on g at high D could be overcome by low [CO₂], and that even lower leaf water potentials did not cause a reduction in hydraulic conductance in these well-watered plants. Reduced g at high D in these species resulted primarily from increased stomatal sensitivity to [CO₂] at high D, and this increased sensitivity may mediate stomatal responses to leaf hydraulics at high D.
Author(s):
Bunce, James A.
Subject(s):
vapor pressure , plant response , stomatal conductance , leaves , carbon dioxide , chemical concentration , leaf water potential , transpiration , Abutilon theophrasti , Glycine max , Gossypium hirsutum , Xanthium strumarium
Format:
p. 1644-1650.
Note:
Includes references
Source:
Plant, cell and environment 2006 Aug., v. 29, no. 8
Language:
English
Publisher:
Oxford, UK : Blackwell Publishing Ltd
Year:
2006
Collection:
Journal Articles, USDA Authors, Peer-Reviewed
Rights:
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.