New Zealand Journal of Crop and Horticultural Science abstracts

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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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