A sensitive experimental system was used: week-old seedlings of flax are subjected to a temporary calcium deprivation. This results in the production of epidermal meristems (meristems are small groups of actively dividing cells) in the hypocotyls (part of the stem between the root and the first leaves), typically 10-20 meristems after a month, provided the seedlings have previously undergone an exposure to different stresses or stimuli (such as drought or cold shock). In control experiments designed to minimize these stresses, the mean number of meristems produced per plant is 0 or 1 after subjecting seedling to calcium deprivation. Recently, the authors have shown that irradiation from a global system for mobile communication (GSM) telephone also triggers production of meristems with a plateau of around six meristems.
Distance between exposed object and exposure source
Seedling irradiation was carried out using a 50 mW Gunn oscillator mounted 25 cm above them. The output angle of the beam was 12°, leading to an estimated meanpower density of the order of 10 W/m² at the base of the hypocotyls.
The output power was monitored using a Golay cellmillimeter wave detector with a detection area of 1.22 cm². The power distribution across the area occupied by the sample was measured using the Golay detector and found to vary by less that ±25% from the center to the periphery of the irradiated area with no other hot spots discernable. The absolute power level incident at the sample was calibrated against an absolute power meter (having an accuracy of ±10%) placed at 25 cm from the end of the Gunn oscillator feed horn.
Roux D et al.
High frequency (900 MHz) low amplitude (5 V m-1) electromagnetic field: a genuine environmental stimulus that affects transcription, translation, calcium and energy charge in tomato.
Beaubois E et al.
Intercellular communication in plants: evidence for two rapidly transmitted systemic signals generated in response to electromagnetic field stimulation in tomato.