Electrical control of growth of the higher plant

Electrochemical events around a root of adzuki bean (Azukia angularis) were studied to pursue the relation between the electric field and the growth. The patterns of the electric potential and pH along a root surface were measured. Theoretical analysis was made for the relation between the pH and the electric potential pattern. The result showed that the electric potential in the apical part near the elongation region reflected the electric current along the root surface including H⁺ flux, whereas the electric potential gradient in the basal part was due to diffusion caused by H⁺ efflux and K⁺ influx. When an electric field was applied in the transverse direction across the root, the root bent to the side of the positive electrode. The application of the electric field also caused the asymmetry of the acidification around the root. The results with a theoretical consideration suggest that the symmetry of the growth was broken by an asymmetrical H⁺ re-distribution made by the external electrical force. The electric field also affected development of lateral roots.