This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (8) Citing Articles via Google Scholar Google Scholar Articles by Bennett, J. M. Articles by Cortes, P. M. Search for Related Content PubMed PubMed Citation Articles by Bennett, J. M. Articles by Cortes, P. M. Agricola Articles by Bennett, J. M. Articles by Cortes, P. M.

Articles

Errors in Measuring Water Potentials of Small Samples Resulting from Water Adsorption by Thermocouple Psychrometer Chambers ¹

Department of Agronomy, University of Florida, Gainesville, Florida 32611

The adsorption of water by thermocouple psychrometer assemblies is known to cause errors in the determination of water potential. Experiments were conducted to evaluate the effect of sample size and psychrometer chamber volume on measured water potentials of leaf discs, leaf segments, and sodium chloride solutions. Reasonable agreement was found between soybean (Glycine max L. Merr.) leaf water potentials measured on 5-millimeter radius leaf discs and large leaf segments. Results indicated that while errors due to adsorption may be significant when using small volumes of tissue, if sufficient tissue is used the errors are negligible. Because of the relationship between water potential and volume in plant tissue, the errors due to adsorption were larger with turgid tissue. Large psychrometers which were sealed into the sample chamber with latex tubing appeared to adsorb more water than those sealed with flexible plastic tubing. Estimates are provided of the amounts of water adsorbed by two different psychrometer assemblies and the amount of tissue sufficient for accurate measurements of leaf water potential with these assemblies. It is also demonstrated that water adsorption problems may have generated low water potential values which in prior studies have been attributed to large cut surface area to volume ratios.

¹ Contribution of Agronomy Department, University of Florida, Gainesville, FL. Florida Agricultural Experiment Stations Journal Series No. 5985.

This article has been cited by other articles:

				C. S. Campbell and K. J. McInnes Response of In Situ Leaf Psychrometer to Cuticle Removal by Abrasion Agron. J., September 1, 1999; 91(5): 859 - 862. [Abstract] [Full Text]