Effects of Periodic- and Transient-Osmotic Stress on Electric Potentials in Bean Roots

Intact bean (Phaseolus mungo) roots were subjected to periodic-and transient-osmotic stress by treatment with a solution oflow water potential °. Both the intracellular potential,E, and the extracellular potential, V, were measured with amultimicrochamber system that combined intracellular microelectrodesand external electrodes. In elongating regions, ° simultaneouslyaffected potentials E and V. The response of E to ° couldbe presented by a transfer function that included dead timeand first order elements. These elements were consistent withthe emergence of an electromotive force, produced by respiration,between the cortex and the stele in the elongating region. (Received January 14, 1983; Accepted June 23, 1983)