Micropropagation of Quercus robur: explant sources and cultural conditions affect in vitro responses differently

In this study results regarding in vitro propagation and conservation of oak germplasm are presented. Fruits and stem cuttings of Q. robur were collected from mature trees. Acorns were put in mould and the seedlings used as source of explants, nodal segments with apical and axillary buds. Nodal segments from stem cuttings were also used. Embryos isolated from acorns were cultured to obtain in vitro growing seedlings: nodal segments from these seedlings were considered a third type of explant. We also tested the same type of explant from shoots at the second cycle of micropropagation. All the explants were placed on Woody Plant Medium with BA 0.5 mg/L. Buds from in vitro seedlings showed the highest percentage of shoot regeneration. The highest number of shoots per productive explant was observed in buds from seedlings grown in mould. With regard to former position of the buds on the stem we observed a prevalent callus proliferation in buds from basal position. Callus occurrence seemed to negatively influence the following shoot development. Afterwards, shoots cultured on Woody Plant Medium containing different auxins, with or without activated carbon, exhibited a good rooting ability. The addition of activated carbon to culture medium seemed to prevent shoots browning. Rooted plantlets were acclimatized after 2 and 11 months. No difference in terms of survival was observed.