Rooting and acclimatization of in vitro propagated microshoots of the Ericaceae

Abstract: The effective methods of rooting and acclimatization in the sphagnum moss of in vitro propagated microshoots of commercially promising plants: Rhododendron ledebourii, Rh. hybridum cv. ‘Cunningham’s White’ and Vaccinium uliginosum cv. ‘Golubaya rossyp’ were developed for the first time. Two methods were studied: 1) rooting in vitro and acclimatization in the substrate and 2) rooting and acclimatization ex vitro in the substrate. Taking into account two factors (rooting of microshoots only in vitro conditions and only from already rooted in vitro regenerants), we have achieved 100% of rooting of bog blueberry cv. ‘Golubaya rossyp’ and 73% of plants adapted to ex vitro conditions. The method of ex vitro rooting in the substrate has been proved as effective for Rh. ledebourii, rooting of it’s shoots reached 80-90% with 87% viable plants. Rh. hybridum cv. ‘Cunningham’s White’ showed the greatest plasticity among the studied species and cultivars on ability to rooting of microshoots. All tested methods gave up to 90-100 % rooted and adapted plants of this cultivar. It was revealed that in vitro rooting microshoots, followed by acclimatization in the substrate was optimal for V. uliginosum cv. ‘Golubaya rossyp’; for Rh. ledebourii – the rooting and acclimatization in the substrate; and for Rh. hybridum cv. ‘Cunningham’s White’ - both methods were effective. From a commercial point of view, the proposed methods decrease the costs of plant production significantly through a reduction in the time and labour needed to obtain well-rooted and acclimatized Ericaceae microplants. Therefore, it could make the micropropagation of commercially promising Ericacea plants in the nursery industry both possible and profitable.