IN-VITRO RESPONSES AND ACCLIMATIZATION OF PRUNUS-SEROTINA WITH PACLOBUTRAZOL

Paclobutrazol (PBZ), a triazole growth retardant known to improve tole rance of various species to stress, was incorporated into the in vitro rooting medium of Prunus serotina var. virens at rates of 0.00, 0.15, 0.30, and 0.60 mg/L with and without 1.0 mg/L indolebutyric acid (IBA ). PBZ significantly reduced shoot growth in vitro but increased/impro ved the quality and coloration. The percentage of water loss from deta ched leaves of in vitro plantlets was significantly reduced by PBZ and IBA. At 4 weeks after transfer to the greenhouse, survival was signif icantly improved by PBZ, IBA, and the combination. Incorporation of PB Z in vitro better enables Prunus serotina plantlets to withstand the s tresses associated with acclimatization.