New Zealand Journal of Crop and Horticultural Science abstracts
Water use by Geraldton wax (Chamelaucium uncinatum Schauer) as measured
by heat balance stem flow gauges
KANDIA AKILAN*
JOHN A. CONSIDINE
Plant Science, School of Agriculture
The University of Western Australia
Nedlands, Western Australia
Australia 6009
JOHN K. MARSHALL
CSIRO Division of Water Resources
Perth Laboratory
Western Australia
Australia 6014
*Present address: CSIRO Division of Water Resources, Perth Laboratory, Western
Australia, Australia 6014.
Abstract Calibrated heat balance stem flow gauges were used
to study the daily water use by Geraldton wax (Chamelaucium uncinatum
Schauer), a plant endemic to the coastal sand plains north of Perth,
Western Australia. Sap flow was recorded for the trunk, primary and secondary
branches, and partially shaded lower east and sun-lit upper west branches in
order to assess the influence of climatic variables, stem development, and
exposure. Irradiance and leaf area strongly influenced diurnal sap flow. Sap
flow in primary and secondary branches was comparable when expressed on a unit
leaf area basis. Defoliation reduced water use of the secondary branch.
Shedding of leaves under water stress, a common phenomenon in Geraldton wax,
probably has similar effects. The level of internal shading influenced water
use in the crown (1.2 and 1.5 kg/day per m2 leaf area for branches
with east and west exposure respectively). The difference in water use was
prominent during the afternoon when the east branch was shaded. The
results demonstrate the value of the heat balance stem flow gauges in measuring
shrub water use directly.
Keywords Geraldton wax; sap flow; water use; Chamelaucium
uncinatum; [[psi]]shoot; hydraulic conductance
New Zealand Journal of Crop and Horticultural Science, 1994, Vol. 22:
285-294
0114-0671/94/2203-0285 $2.50/0 (c) The Royal Society of New Zealand
1994
PDF file of entire paper: medium quality (2982K); (scanned from paper original: notes about this process)
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