STRAWBERRY COLD HARDENING INVESTIGATIONS IN VITRO

Changeable winter conditions in temperate climatic zones often cause significant strawberry yield loss, especially for introduced high berry quality cultivars. This research was carried out to investigate the ability of different strawberry cultivars to acclimate in low temperatures and retain cold acclimation during freeze-thaw cycles when sharp temperature fluctuations occur. All experiments were performed in climatic chamber in vitro under strict control of different acclimation – deacclimation conditions. Our freezing in vitro experiments reveal that cold hardy strawberry cultivars remain sufficiently acclimated for 4 days in “thaw” conditions of +22°C temperature, susceptible ones - for 2 days in the same temperature. Plants have abilities for secondary acclimation. The survival rate of strawberry plants acclimated in vitro second time was up to 46% higher than of plants without second acclimation. Expression of strawberry COR gene analogues were evaluated every 7 days during primary and secondary acclimation. Correlation between expression intensity of this gene and acclimation level - cold hardiness was discussed.