DEHYDRATION OF DORMANT APPLE BUDS AT DIFFERENT STAGES OF COLD ACCLIMATION TO INDUCE CRYOPRESERVABILITY IN DIFFERENT CULTIVARS

Abstract

Survival in liquid nitrogen of dormant vegetative buds from several cold-hardened apple cultivars was greater with buds which were dehydrated prior to cryopreservation than with nondehydrated buds. Buds collected early in the cold-acclimating period suffered injury as a result of dehydration, but the percent survival of the dehydrated buds, after storage in liquid nitrogen, was greater than that of nondehydrated buds. As cold acclimation progressed, buds became more resistant to the dehydration stress and survival in liquid nitrogen increased following dehydration for all cultivars. Survival in liquid nitrogen of nondehydrated buds increased for LN 2 -hardy but not for LN 2 -tender cultivars, as cold acclimation progressed. The magnitude of the dehydration-induced increase in survival in liquid nitrogen was cultivar dependent.Key words: Malus domestica, apple, cryopreservation, gene resources, cold hardiness