potometer


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Porphyrinclick for a larger image
Fig. 258 Porphyrin . Compound structure.
Potometerclick for a larger image
Fig. 259 Potometer .

potometer

an instrument designed to measure the rate of absorption of water by a cut shoot and hence, indirectly, the rate of TRANSPIRATION by the shoot in a particular set of conditions, which can be varied.

At the start of the experiment an air bubble is introduced into the tubing adjacent to the graduated scale. Reservoir A supplies water to replace that lost by the shoot, the amount taken up being indicated by the movement of the air bubble along the scale. Opening the stopcock at the end of a time period causes water from reservoir B to force the air bubble along the tube, ready for a fresh start.

Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
References in periodicals archive ?
Our objective was to test the capacity of the Heat Dissipation Technique to accurately measure water use of tropical trees, by comparing it with water uptake of trees held in potometers. Potometers are a useful tool for measuring water uptake (Fig.
Two trees of each species were chosen for potometers and two more trees were kept as controls.
Sap flow measurements: We used the heat dissipation technique (HDT; Granier 1985) to measure sap flow of intact trees and trees installed in potometers. This technique measures the temperature of a line heat source implanted in the sapwood of a tree, referenced to the sapwood temperature measured 2 cm below the heated needle.
Cut trees in potometers had their bases in 10 l reservoirs containing a solution of formaldehyde (0.05%) to delay the development of microorganisms and plugging of the xylem (Sperry et al.
Leaf water potential and stomatal conductance: In order to evaluate whether trees in potometers behaved similarly to intact trees, we conducted leaf-level measurements of water status.