Abstract/Summary

BACKGROUND: Precise temperature control in several key areas during cryopreservation of dormant, winter apple buds is critical for maximal survival. OBJECTIVE: To consider the effects of pre-harvest temperature, the duration of incubation at -30°C and variation in rewarming rate on survival. MATERIALS AND METHODS: Dormant winter buds of Malus x domestica cultivars were harvested with two different acclimation histories and cryopreserved with variation in incubation time at -30°C. Recovery from LN using slow, intermediate and rapid rewarming was investigated as well as preservation after prolonged storage at -4°C. RESULTS: The effects on survival of preharvest temperature regime and an altered -30°C incubation regime are cultivar dependent and an increase in rewarming rate has a strong negative effect on recovery. CONCLUSION: Post-thaw survival of the winter-dormant buds can be compromised by increased temperature over a period as short as 5 days prior to bud harvest. Varying incubation times at -30°C produce variable, cultivar dependent, survival and moderate increases in rewarming rates can also radically reduce survival.