Rana Munns and John Boyer
Water relations of plants are essential indicators of plant health and productivity.
However, they are among the most difficult of all plant properties to measure. This is partly because they are never static and rarely steady, yet some measurements like water potential can only be measured when the tissue is at equilibrium.
Methods for measurement of the water status of plants and soils have been described in a practical handbook by JS Boyer ("Measuring the Water Status of Plants and Soils," Academic Press, San Diego, 1995). The full content is available from the University of Delaware website - here. This book describes the practical details of measurements of leaf water potential with the pressure chamber, tissue water and osmotic potential with the thermocouple psychrometer, and turgor pressure with the pressure probe.
The theory behind these measurements is given by PJ Kramer and JS Boyer "Water relations of plants and soils". Academic Press, San Diego, 1995, also provided by the University of Delaware - here.
Boyer, JS. 1995 "Measuring the Water Status of Plants and Soils". Academic Press, San Diego. Also available at the University of Delaware website http://dspace.udel.edu:8080/dspace/handle/19716/2828.
Kramer, PJ and Boyer JS. 1995 "Water relations of plants and soils". Academic Press, San Diego. Also provided by the University of Delaware http://dspace.udel.edu:8080/dspace/handle/19716/2830.