The effects of the length of the culture period and size of the plantlets at the potting on survival of the tissue-cultured strawberry plantlets raised without the operation of acclimatization

The conditions to eliminate the operation of acclimatization of tissue-cult ured strawberry plantlets were examined. Strawberry plantlets cultured in the rooting medium following propagation c ulture were transplanted into small pots without the operation of acclimati zation, and were raised on the shelf system with manual irrigation. The per centage of plantlets taking root and surviving in the pots after transplant ation increased, as the culture period in the rooting medium was lengthened . And, the survival percentage of the plantlets, cultured for 54 days in th e rooting medium, after potting reached 95 to 100%. Even in cases where the plantlets were cultured for only 35 days in the rooting medium, the plantl ets which had five or more leaves, or whose longest roots measured 40 mm or more were all able to survive after potting. In the suitable season for potting, from late April to early June, the plan tlets, cultured for 54 days in the rooting medium, were potted several time s without the operation of acclimatization, and were raised with cheeseclot h cover and water spraying three times per day by microsprinklers. Conseque ntly, 96 to 100% of these plantlets survived, indicating that the operation of acclimatization of well-cultured strawberry plantlets is not necessary prior to transplanting them into the field.