Water Relations of Seagrasses: STATIONARY VOLUMETRIC ELASTIC MODULUS AND OSMOTIC PRESSURE OF THE LEAF CELLS OF HALOPHILA OVALIS, ZOSTERA CAPRICORNI, AND POSIDONIA AUSTRALIS

摘要

The stationary volumetric elastic modulus (εs) 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 εs plus intracellular osmotic pressure (εs + IIi) and IIi. The estimates of (εs + IIi) were made using a linear displacement transducer to measure very small changes in thickness of leaf tissue produced by changes in external osmotic pressure (IIo). εs increases with increasing turgor pressure in each of the species and the maximum values of εs are: 22 megapascals for H. ovalis, 17 megapascals for Z. capricorni, and 51 megapascals for P. australis.