Long-term conservation of Diospyros germplasm using dormant buds by a prefreezing method

Cryopreservation of Diospyros at-150°C followed by a prefreezing treatment using dormant winter buds was investigated. Twig sections bearing one bud each were first partly dehydrated at room temperature for 3 h. Then they were subjected to a successive prefreezing at-5, -10, -15, -20 and-30°C at 24 h intervals, and finally preserved at-150°C in a deep freezer. Thawing in the air at 25°C gave the highest rate (about 70%) of in vitro shoot formation from cryopreserved buds. Shoot regeneration by bud grafting was not successful. Dormant buds appear to be a suitable material for long-term storage of some Diospyros species.