Introduction
Experimental study of the effects of electricity on plant growth began in 1746. Early researchers discovered the
application of electricity in agriculture for different purposes such as for seed treatment, seedling growth, plant
growth, insect control and so on. Although their research aims were good, their apparatus, experimental designs
and methods, process, dosage, amplitude of voltage, and the treatment time were not scientific so that they often
got contradictory results [1].
The application of electricity, magnetism, monochrome light and sound can stimulate the growth of plants to
a great extent. The energies are applied to the seeds, plants, soil or the water and nutrients. This technology
termed as electro-culture, can protect plants from diseases, insects and frost. These methods can also reduce the
requirements for fertilizer or pesticides [2].
It is well known that currents of electricity exist in the atmosphere. Clouds are charged and discharged. There
is constant change of electricity from earth to air and from air to earth. The earth is the reservoir for all electricity.
The electricity is the potent factor in the economy of nature and has more to do with the growth and developments
of plants. Plant food is carried throughout the plant by means of the flow of sap, these currents circu-lates through all rootlets and centre as it were, in the stalk, carrying their tiny burdens of various elements and
depositing them in the proper places. This phenomenon of sap circulation can be doubled due to electricity [3].
The several approaches of electricity were reviewed [4]. Morar [5] experimented with electrostatic field
ranging 2 to 6 kV/cm with exposure time of 1 to 30 sec. for bean seeds. Huang [6] treated cucumber seeds with
field strength of 1 kV to 7 kV/cm. Efe [7] conducted experiments with corona shocking instrument for cotton
seeds. Pozeliene [8] processed rapeseeds with corona discharge field in the conveyer type electric separator.
Zhou [9] designed new atmospheric plasma device, to explore approximate voltage of plasma treatment for tomato
seeds. Aladjadjiyan [10] treated lentil seeds by using microwave of 2 - 45 GHz. frequency. More [11] utilized
microwaves for sorghum.
Out of these all possibilities, it was felt that electrostatic field, microwave field and corona discharge methods
were prominent. Hence a comparative study was undertaken to verify the effects of high voltage application for
tomato seed treatment. Based on these pretreatments of seed before sowing, the study was planned.