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Some Aspects of the Water Relations of the Lichen Parmotrema Tinctorum Measured Using Thermocouple Psychrometry

Published online by Cambridge University Press:  28 March 2007

R. P. Beckett
Affiliation:
NU Research Unit for Plant Growth and Development, Department of Botany, University of Natal, Private Bag X01, Scottsville 3209, Pietermaritzburg, South Africa

Abstract

The thermocouple psychrometer was used to determine water potential, Ψ and its components in the lichen Parmotrema tinctorum. Data suggested that using conventional pressure-volume curves to study the water relations of lichens may give anomalous results, possibly because lichens may contain appreciable amounts of intercellular water. A way of correcting pressure-volume curves to remove the effect of intercellular water is discussed. Parmotrema tinctorum had a very low osmotic potential at full turgor (c. −2.5 MPa), and a low bulk modulus of elasticit (c. 2.1 MPa). As a result, P. tinctorum lost turgor only when the relative water content dropped below 0.47. Likely benefits of this for the lichen are discussed.

Type
Research Article
Copyright
Copyright © British Lichen Society 1996

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