| Summary: | Typescript Thesis (MSc) -- University of Melbourne, Faculty of Science, 1959 Includes bibliographical references (leaves 135-140). Although it is generally recognised that water is one of the main limiting factors in the development of vegetation in Australia, comparatively little physiological work has been done on the water economy of native plants. Ibis is particularly true of the water relations of trees; yet, due chiefly to the scarcity of water in extensive areas of Australia, the proportion under forest is the smallest for any of the continents, except Antarctica. A large proportion of the published work on ecological aspects of plant water relations has been concerned with determinations of the osmotic pressure of the cell sap, although values of osmotic pressure give no indication of the ability of plant tissues to take up water. Ibis ability is measured by the suction pressure of the tissue. Owing to the difficulty involved in its determination, suction pressure has been measured comparatively rarely in physiological and ecological studies. Most of the work included in this thesis consists of investigations relevant to the suction pressure and water deficit of leaf tissue. Juvenile leaves of Eucalyptus globulus Labill. were used as a source of material in the experiments which will be described. As characteristically Australian trees, the eucalypts are a natural choice for study. This particular species (blue gum) is native to arena of south-east Australia, but it is cultivated widely in other countries, so that material is available to many research workers overseas. In addition, saplings of E. globulus had been planted in a garden at the rear of the Botany Department in Melbourne in 1954, and these provided a good supply of leaves throughout the course of the Investigations detailed below. Much of the work on the water relations of plants ms been concerned with the absorption of water, the ascent of sap, and transpiration. Transpiration, its measurement, and the factors affecting it, have ...
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