To study the effects of weak and extremely low frequency magnetic fields on the growth and germination of spruce seedlings that were exposed simultaneously to different pH levels (pH 2, 3, 6, and 7 at 50 Hz, and 5.3, 5.5, and 6 at 46 Hz).
The study could be relevant for understanding how the decay of modern forests exposed to acid rain may be influenced by surrounding electromagnetic fields.
| Exposure | Parameters |
|---|---|
|
Exposure 1:
50 Hz
Exposure duration:
continuous for 12 h/day on 7 days
|
|
|
Exposure 2:
46 Hz
Exposure duration:
continuous for 12 h/day on 7 days
|
|
| Frequency | 50 Hz |
|---|---|
| Type | |
| Waveform | |
| Exposure duration | continuous for 12 h/day on 7 days |
| Exposure source | |
|---|---|
| Setup | pair of Helmholtz coils with a radius of 20 cm, a distance of 40 cm and 140 turns of 1.4 mm copper wire; petri dishes with seeds between the coils; coils inside a 70 cm x 70 cm x 60 cm pasteboard box, insulated with styrofoam and grounded by aluminum foil |
| Sham exposure | A sham exposure was conducted. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 105 µT | - | measured | - | +/- 10 µT |
| magnetic flux density | 26 µT | - | measured | - | +/- 4 µT |
| Frequency | 46 Hz |
|---|---|
| Type | |
| Waveform | |
| Exposure duration | continuous for 12 h/day on 7 days |
| Exposure source |
|
|---|---|
| Sham exposure | A sham exposure was conducted. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 10 µT | - | measured | - | +/- 1 µT |
The data showed that exposure to the magnetic field slightly reduced the length of the seedlings and delayed germination at low pH levels: A 26 µT magnetic field at 50 Hz reduced the length of the seedlings at pH 2, delayed germination between pH 2 and 3, and caused no effects or were even stimulatory at pH 6 and 7.
At a higher magnetic flux density (105 µT) the length of radicles, fresh weight, and germination were reduced mostly at pH 2 and 3 and with a higher statistical significance than at 26 µT. Germination was influenced during the first days of germination, and later the effect diminished rapidly.
A 10 µT magnetic field at 46 Hz stimulated only the length of the radicles.
The data indicate that stress factors such as an acid environment, together with certain electromagnetic field sources, could have stronger effects on the development of plants than without magnetic fields.
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