In all experiments where the plant roots were exposed to the electromagnetic fields , the protocol of Stenz and Weissensel (1993) was followed, with some minor modifications. MES-buffered medium, without salt, was used. It was aerated and stirred by air from the aquarium pump. Only a weak electric field was used, which did not cause injury to the roots. Only those roots which either did not show any sign of damage (as a change in colour of the root tip) or were able to grow continuously after disconnection of the field were analysed.