Influence of pulsed electric field on growths of soil bacteria and pepper plant

DC 20 volt of electricity was charged to the electrodes placed around hot pepper plants to induce electrical redox reaction. Anode and cathode were periodically exchanged at intervals of 30 seconds to develop a pulsed electric field (PEF), by which the ORP of the soil around the pepper plant roots were fluctuated from 17 to −13 volts. Mean viable cell number of the intrinsic bacteria in five different positions was variable from 77,000 to 396,000 around electrodes and 339,000 to 680,000 around plants in the PEF, and 538,000 to 927,000 around plants in the conventional field. The mean viable cell number of the extrinsic bacteria ( R. solanacearum ) in five different positions was variable from 15,000 to 47,000 around electrode and 152,000 to 374,000 around plant in the PEF, and 294,000 to 607,000 around plants in the conventional field. Mean 3.93 and 5.67 of hot pepper plants were infected with bacterial wilt every two days by passive and active infection, respectively, in the conventional field. Mean 1.25 and 2.5 of hot pepper plants were infected with bacterial wilt every two days by passive and active infection, respectively, in the PEF. Mean sprouting number of seeds in the PEF and conventional field and was 45.0 and 48.2, respectively. Mean dry weight of hot pepper plants was 3.15 g and 2.51 g in the PEF and conventional field, respectively. The TGGE band pattern in the PEF was not very different in comparison with that in the conventional field (B and D) based on the band number, which corresponds to the bacterial diversity. This study suggests that the PEF would be functioning as an environmental factor to inhibit bacterial growth rather than to be a physical agent to destroy bacterial cells.