On the mechanism of 60-Hz electric field induced effects in Pisum sativum L. roots: Vertical field exposures

Roots of Pisum sativum L. were chronically exposed to 60-Hz vertical electric fields ranging from 150 to 450 V/m in an aqueous medium whose conductivity was approximately 0.07 S/m. Control and exposed roots were grown concomitantly in the same tank whose medium was continuously circulated and maintained at 19° C. The experiments were conducted blind. Root growth rates were determined daily and the mitotic index was determined for various intervals over a 24-h period, ranging from 12 h before to 12 h after electrode energization. Root growth rates were affected in a dose dependent relationship by exposures greater than 250 V/m. Mitotic indices were not affected by 150 V/m but were affected at 350 V/m; the former exposure did not alter root growth rates, the latter did. The growth rates of vertically exposed roots were compared to those of horizontally exposed roots; the former are more sensitive at a given field strength. The observations are consistent with the postulate that the electric field acts upon the cell through a perturbation of the transmembrane potential.