Cryopreservation and Acclimatization of

Romanian tomato (Lycopersicon esculentum Mill.) cultivars have been cryopreserved by encapsulation-dehydration and successfully acclimatized to ex vitro growth conditions. Shoot tips were excised from in vitro grown plants then precultured for 24 h in various sucrose concentrations, dehydrated up to 6 h in laminar air flow prior to direct immersion in liquid nitrogen (-196°C) for 24 h. Different parameters have been studied: the effects of osmoprotection and desiccation duration on the regrowth of cryopreserved shoot tips, the effects of various IBA concentrations on rooting and the ex vitro cclimatization of plants recovered from liquid nitrogen. The highest frequency of regrowth (72% cv. 'Pontica') was obtained when encapsulated explants were precultured in 0.5 M sucrose and the moisture content (fresh weight basis) of alginate beads was 23%. The highest rooting rates (58% to 77%) for all cultivars were observed for shoots grown on MS medium supplemented with 1.0 mg/l IBA. The rooted plants could be easily acclimatized ex vitro with up to 100% survival.