Short Communications

Measurement of water potential in the trunks of citrus trees using screen-caged thermocouple Psychrometers

Published in: South African Journal of Plant and Soil
Volume 5, issue 4, 1988 , pages: 219–221
DOI: 10.1080/02571862.1988.10634990
Author(s): D.M. OosterhuisDepartment of Agronomy, U.S.A., M.J. SavageDepartment of Soil Science and Agrometeorology, Republic of South Africa, H.H. WiebeBiology Department, U.S.A.

Abstract

Screen-caged thermocouple Psychrometers were used to non-destructively measure the water potential (ψ) in the trunks of mature citrus trees (Citrus sinensis L. Osbeck), and the values compared with the ψ of covered, exposed, and shaded leaves of the same tree. The installation and thermal insulation of the trunk Psychrometers is described. Adequate thermal insulation of the trunk and enclosed Psychrometers was difficult despite a covering of polyurethane foam and reflective aluminium foil, and relatively large temperature gradients were indicated. The measured ψ's were, however, similar to covered leaf ψ and within the expected range when compared to the leaf and soil values as well as with other published values. Possible methods of further reducing the thermal gradients are discussed.

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