Cold storage of shoot cultures and mycorrhizal inoculation of plantlets

Two methods have been examined to reduce labour requirement or to extend the acclimatization period: (1) To prepare large quantity of in vitro cultures for rooting using a cold storage period before the rooting phase. (2) To shorten the growth time and to improve the vigour of micropropagated rootstocks by mycorrhizal inoculation. Both methods can be used to reduce the labour requirement in the spring time, and to extend the transplantation period of the acclimatized plants to the outdoors till the beginning of July. The in vitro cultures can be stored at 4°C before rooting. The cold treatment should begin at half time of the multiplication period or the elongation period. In this case there is no harmful influence on rooting. Significant growth stimulating effect can be achieved using selected clones of mycorrhiza lines for inoculation of the plantlets.