Fig. 5

A schematic drawing of the electric-application setups that were used to determine the effects of a DC  electric field on the elongation growth of maize seedling organs (Scheme 1) and the gravitropic response of seedling coleoptiles (Scheme 2). In the first setup (Scheme 1) twenty 72-hour-old seedlings (S) were arranged on two plexiglass plates (P) covered with agar (3 % agar prepared on the control medium) in which a platinum wire (PW) in the form of a flattened spiral was placed. In the second setup (Scheme 2), one 96-hour-old maize seedling, after treatment with EF, was used to study the effect of an electric field on the gravitropic response of the maize seedling. In the second setup, the seedling (S) was supported by a carcass made of plexiglass (C), which in turn was connected to the chamber containing the seedling root system immersed in the control medium (CM). The current from a DC power supply (Protek, DC power supply, model 3003, Korea) was fed to the coleoptile using a platinum wire (PW), the end of which in the form of 2-3 coils (slightly larger in diameter than the diameter of the coleoptile) which was placed over the tip of the coleoptile. In order to obtain contact between the platinum wire and the coleoptile, the gap between them was filled with agar (A, 3% prepared on the control solution). The voltage and resultant current from the DC power supply were measured by the volte (V) and ampere (A) meter. A similar procedure for studying the effects of an electric field on the growth of maize seedlings (Fig. 5, Scheme 2) has been previously used by Desrosiers and Bandurski [19]. The setup (Scheme 1) is our idea