The Quantative Analysis of Water Potential/Symplastic Water Volume Curves

Abstract

The relationships between expressed sap volume and the major components of plant water potential can readily be investigated by using well established pressure-chamber techniques. These relationships are analysed and a method is developed for normalizing potential/volume characteristics and displaying them on a Höfler diagram. Relationships are given as mathematical equations and only three parameters are needed to define a set of characteristic curves, so that the method is suitable for use in the computer processing of pressure-chamber sap-volume measurements. To illustrate the method, potential/volume characteristics are given on Höfler diagrams for leaves taken at three times in the day from two apple trees, one irrigated and one droughted.