Cryopreservation of cold-tender apple germplasm

Unlike cold-hardy apple germplasm, dormant vegetative buds from cold-tender accessions require stabilization of meristematic tissue to protect against injury during desiccation and cryopreservation, Dormant buds of six apple cultivars [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf. 'Cox' s Orange Pippin', 'Einshemer','Golden Delicious', 'Jonagold','K-14', and 'M utsu'] collected at specific intervals in 1993, 1993, and 1995 at Geneva, N .Y., were stabilized by encapsulation in 5% alginate, treated with step-wis e imbibition of 0.5 to 1.0 M sucrose and 0.2 ar raffinose solution, and des iccated with forced air at 0 degrees C. Sugar-alginate stabilization reduce d injury during desiccation, increased cold hardiness of the six cold-tende r cultivars frozen to -30 degrees C, and improved recovery following cryopr eservation of buds collected before optimal cold acclimation was attained. Sucrose tissue levels did not increase following stabilization treatment, b ut levels of glucose and fructose, and of an unknown disaccharide increased . This procedure used nontoxic cryoprotectants, and has potential to expand the scope of dormant bud cryopreservation to include cold-tender apple ger mplasm.