This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Tyerman, S. D. Search for Related Content PubMed PubMed Citation Articles by Tyerman, S. D. Agricola Articles by Tyerman, S. D.

Articles

Water Relations of Seagrasses

STATIONARY VOLUMETRIC ELASTIC MODULUS AND OSMOTIC PRESSURE OF THE LEAF CELLS OF HALOPHILA OVALIS, ZOSTERA CAPRICORNI, AND POSIDONIA AUSTRALIS

School of Biological Sciences, University of Sydney, New South Wales 2006, Australia

The stationary volumetric elastic modulus (_s) of the leaf cells of three seagrasses (Halophila ovalis (R.Br.) Hook, Zostera capricorni Aschers, and Posidonia australis Hook f.) was evaluated from estimates of _s plus intracellular osmotic pressure (_s + II_i) and II_i. The estimates of (_s + II_i) were made using a linear displacement transducer to measure very small changes in thickness of leaf tissue produced by changes in external osmotic pressure (II_o). _s increases with increasing turgor pressure in each of the species and the maximum values of _s are: 22 megapascals for H. ovalis, 17 megapascals for Z. capricorni, and 51 megapascals for P. australis.

There is a hysteresis in thickness changes versus changes in II_o which indicates a hysteresis in the relationship between volume and turgor pressure. The hysteresis results in _s being different for swelling and for shrinking cells over the same range of II_o and this may be important in other aspects of plant-water relations.

A new design of an apparatus employing a linear displacement transducer for measuring very small changes in tissue thickness is described. The new design has the advantages of virtually frictionless movement and a precision of 0.05 micrometer.