Different measurements were performed at 2, 4, and 8 days of growth.
Exposure duration: continuous for up to 8 days
Exposure duration: continuous for 4 days
Exposure duration: continuous for 12 hours
Vicia faba seeds were weight matched, disinfected and activated by soaking them overnight in Hoagland's solution at room temperature (25 ± 2°C). They were divided into: Group I - control Group II - exposed to varying magnetic field intensities viz. 5.0 ± 0.25, 50 ± 2.5, or 100 ± 5 µT, at 50 Hz, till lateral roots were formed (day 8, termed total exposure) Group III - grown outside the field until germination as evidenced by formation of the primary root (day 4) and then shifted into the varying magnetic field for the lateral root formation (termed delayed exposure). A separate study was also undertaken to evaluate the effect of different magnetic field intensities on the imbibition of Vicia faba seedlings which were soaked in Hoagland medium and exposed for 12 hours (overnight).
|Setup||The magnetic field exposure facility was comprised of 24 wooden boxes (size 0.5 m x 0.5 m x 0.5m). Individual bobbins were wound around each box forming two sets of horizontal coils (each set consists of 50 turns) and three sets of vertical coils (each set consists of 25 turns), capable of producing horizontal, vertical, circular and elliptical magnetic fields. The vertical coils were movable and their position was adjusted so as to obtain a uniform magnetic field intensity inside the exposure area which was ensured by measurement. Coefficient of variation was found to be <6% over the whole volume of the bobbin.|
|Additional info||A similar set-up having 12 numbers of bobbins was established without energizing the coils for control. Enough spacing (2.78 m) was provided between the control and experimental groups to avoid any interference of the magnetic fields. The geomagnetic field inside the boxes was: Z (vertical) = 15.894 ± 0.141 µT and H (horizontal) = 39.430 ± 0.013 µT.|
|Exposure duration||continuous for 12 hours|
There was no significant change in physical parameters and biochemical constituents between control and experimental plants.
The comparison between the control and exposed seedlings showed that α-amylase enzyme activity significantly decreased at 5, 50 and 100 µT on day 2 and 4 of growth. β-amylase and protease showed a significant decrease in enzyme activities on day 2 and 4 at 100 µT, whereas enzyme activity of lipase significantly decreased only on day 2 of growth at 100 µT.
At day 8 of growth, all enzyme activities reverted back to the same as control.
There was also a significant increase in ³H-thymidine uptake as well as in mitotic index at 100 µT ("delayed exposure" (group III) on day 8; field 2).
The data suggest that exposure to power frequency electromagnetic fields up to 100 µT on germinating seedlings does not cause any permanent damage since the initial alteration in some important enzymes under the magnetic field exposure were returned to control values on day 8 of growth.