Abstract
It is very important to measure water potential for analyzing its biological physiology and growth mechanism. There are some reports about measurement of it, but some of them are destructive method. One method of them is the pressure-chamber method that needs some sample and is difficult to measure automatically.
Then, as the dielectric constant of water is very large comparing other organism in a stem, it is tried to measure the water potential by capacitance method which detects capacitance in proportion to the amount of water in the stem.
Two capacitance methods are developed, and one of them reads water potential directly using ceramics and the other detects the amount of water in a stem by two electrodes surrounding a stem.
The result of measurement is followed that the response of water potential in a stem decreases with vibration to sudden lighting like step-function. The phenomena is simulated by electric circuit by the analogy of water flow to current and water potential to voltage.
