Thermocouple psychrometer for measurements of water potential in plant tissues by isopiestic method
2010
Kotov, A. A (Andreĭ Aleksandrovich) | Kotova, L. M
The paper describes a thermocouple psychrometer for measurements of water potential (ψw) and its components—osmotic potential (ψs ₊ m) and turgor pressure (ψp)—in biological objects. The isopiestic method applied in this work does not require preliminary scarification of plant material for eliminating cuticular resistance to diffusion of water vapors. The device is reliable and simple in operation owing to an original design of replaceable plungers carrying the thermocouples. A modified construction of the lid for a thermocouple chamber and the application of a cryoholder excluded the necessity of removing the sample from the chamber after ψw measurements prior to its freezing in liquid nitrogen and subsequent thawing for determination of ψs ₊m. This feature improves the accuracy of determining ψp, which is calculated as ψw − ψs ₊ m. The device can operate with minimal quantities of plant material and allows determination of all three components (ψw, ψs ₊ m, ψp) for the same sample.
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