EFFECT OF ACTIVATED CHARCOAL ON IN VITRO PROPAGATION OF WESTERN EUROPEAN ORCHIDS
For all the tested species, the addition of activated charcoal (0.02–0.1 % w/v) to the sowing medium resulted in a lower germination rate and a slower development.
On the other hand, the effect of the addition of activated charcoal (0.02–0.3 % w/v) to the transplantation medium was in most cases a growth stimulation. Species with a high release of polyphenols in the sowing medium (Anacamptis pyramidalis, Dactylorhiza spp., Epipactis spp., Gymnadenia spp., Listera ovata) had a noticeably better development after being transplantated on a medium with activated charcoal. On the contrary, no stimulating effect was noticed with cultures of Ophrys spp., Orchis spp. and Spiranthes spp. The last ones gave no visible release of polyphenols in the culture medium.