In our research concerning monitoring the biological effects of weak non-ionizing EM radiation on organisms we tested the importance of their physiological state. This has already been mentioned by some authors, but not researched enough (McLeod et al. 1992, Adey 1984, Findl 1993, Vodovnik & Miklavèiè 1995, Kaiser 1988, Blank & Soo 1993). The knowledge about the relation between the physiological state of organisms and their sensitivity and reactivity to defined EM radiation is very important to ascertain health risks of EMF to humans and other organisms.
We examined the effects of sinusoidal magnetic fields (MF) on the germination and growth of spruce seedlings Picea abies (L.) Karsten exposed to two levels of drought stress (88 and 176 g/l) produced by polyethylene glycol (PEG). Homogenous sinusoidal magnetic field (50 Hz, 25 and 100 µT, exposure 12 h/day) was generated by a specially designed computer controlled generator including a pair of Helmholtz coils.
MF at 25 µT strongly inhibited the germination and growth of seedlings: with PEG 88 g/l by 20-73% and with 176 g/l by 12-59%. The results are repeatable and statistically highly significant. In the absence of PEG there were no significant effects. Especially significant and repeatable was the inhibition of fresh weight (88 g/l by 17-21%, 176 g/l by 6-22%). At 100 mT the inhibition of germination was higher when the radicle just emerged, later it diminished. With 88 g/l it was inhibited by 21-13% and with 176 g/l by 51%-67%. The growth of the radicle and fresh weight of seedlings were inhibited, too; in the absence of PEG there were no visible effects, germination was even slightly stimulated.
The results are relevant to human health, since it was demonstrated that stress conditions make organisms more vulnerable to EM radiation, even when there are no observed biological effects on the same systems without stress.