The plant pressure chamber is used to measure midday stem water potential as a means to assess the current tree water status.
Stem water potential readings give an integrated measure of water availability across the entire rootzone to the tree. This measurement can be considered equivalent to measuring blood pressure in humans.
Rosati, A., Metcalf, S., Buchner, R., Fulton, A., and Lampinen, B. 2006. Tree water status and gas exchange in walnut under drought, high temperature and vapour pressure deficit. Journal of Horticultural Science and Biotechnology 81: 415-420.
Lampinen, B. D., Shackel, K. A., Southwick, S. M., Olson, W. H., and Dejong, T. M. 2004. Leaf and canopy level photosynthetic responses of French prune (Prunus domestica L. ‘French’) to stem water potential based deficit irrigation. Journal of Horticultural Science and Biotechnology 79: 638-644.