Abstract
Dianthus (Dianthus hybryda hort. cv. Sakuranadeshiko) shoot tips were automatically frozen by computarized programfreezer (FFP-190, Osaka Sanso Industry Co. Ltd.) . After pretreatment with 10% DMSO and 3% glucose for 10, 60, and 120 min. at 0, 20 and 30°C respectively, each sample of shoot tips set in 0.5 ml plastic straw were frozen according to freezing program (Table 1) . Hundred percent of shoot tips were survived by pretreatment of cryoprotectants, except pretreatment at 30°C. Hundred percent shoot tips which thawed rapidly in water 37 or 0°C were survived and regenerated shoots with 40 days culture on modified MS medium, but only 35.2% shoot tips which thawed slowly in air at 15°C were survived. In the process of rewarming in air, survival rate of shoot tips declined sharply during slow rewarming above -40°C. After 210 days of strage in liquid nitrogen (LN2), more than 91.7% of shoot tips were regenerated into plantlets.
