Cryopreservation of apple dormant buds and shoot tips.

Shoot tips excised from apple (Malus domestica Borkh. cv. Golden Delicious) dormant buds immediately before freezing were successfully cryopreserved using three different methods (vitrification, encapsulation-dehydration and two-step freezing). Two-step freezing produced the highest in vitro growth recovery (83%) of cryopreserved shoot tips, followed by vitrification (60%) and encapsulation-dehydration (33%). By contrast, when dormant buds were cryopreserved using the two-step freezing technique, shoot tips excised from buds after rewarming and cultured in vitro displayed only 16% recovery.