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Diurnal depression of leaf hydraulic conductance in a tropical tree species

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Brodribb, TJ and Holbrook, NM (2004) Diurnal depression of leaf hydraulic conductance in a tropical tree species. Plant, Cell and Environment, 27 (7). pp. 820-827. ISSN 0140-7791

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Abstract

Diurnal patterns of hydraulic conductance of the leaf lamina
(
K
leaf
) were monitored in a field-grown tropical tree
species in an attempt to ascertain whether the dynamics of
stomatal conductance (
g
s
) and CO
2
uptake (
A
leaf
) were
associated with short-term changes in
K
leaf
. On days of high
evaporative demand mid-day depression of
K
leaf
to between
40 and 50% of pre-dawn values was followed by a rapid
recovery after 1500 h. Leaf water potential during the
recovery stage was less than
-
1 MPa implying a refilling
mechanism, or that loss of
K
leaf
was not linked to cavitation.
Laboratory measurement of the response of
K
leaf
to
Y
leaf
confirmed that leaves in the field were operating at water
potentials within the depressed region of the leaf ‘vulnerability
curve’. Diurnal courses of
K
leaf
and
Y
leaf
predicted
from measured transpiration, xylem water potential and
the
K
leaf
vulnerability function, yielded good agreement
with observed trends in both leaf parameters. Close correlation
between depression of
K
leaf
,
g
s
and
A
leaf
suggests that
xylem dysfunction in the leaf may lead to mid-day depression
of gas exchange in this species.

Item Type: Article
Keywords: gas exchange; leaf hydraulic conductance; midday depression; stomata; water use.
Journal or Publication Title: Plant, Cell and Environment
Page Range: pp. 820-827
ISSN: 0140-7791
Identification Number - DOI: 10.1111/j.1365-3040.2004.01188.x
Additional Information:

"The definitive version is available at www.blackwell-synergy.com"

Date Deposited: 30 Nov 2007 02:06
Last Modified: 18 Nov 2014 03:25
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