Leaf water balance during oscillation of stomatal aperture.

Continuous transpiration and beta-guage measurements were made on cotton plants, the stomatal apertures of which had been induced to oscillate, thus allowing a water balance to be made, and leaf potential to be measured as functions of time.Analyses showed phase differences between the water entering and leaving the leaf. Also, from the phase relationship between the flow into the leaf and the water potential in the leaf it was shown that the water potential in the xylem of the plant also oscillated. This is proposed as a necessary condition for the stomates of all the leaves of a plant to oscillate in phase.It is convenient to describe the dynamics of the phenomena using a simple electrical analogue, and the usefulness and limitations of the model are discussed.