SCREENING STRAWBERRY CULTIVARS FOR COLD HARDINESS IN VITRO

Authors:	P. Palonen, D. Buszard
Keywords:	Fragaria × ananassa, cold tolerance, winterhardiness
Abstract: This study examined the possibility of screening strawberry cultivars (Fragaria × ananassa Duch.) for cold hardiness in vitro. Cultivars Beaver Ruby, Chambly, Kent and Selva were grown on three different media: A) MS medium supplemented with 1.0 mg/L BAP, 0.1 mg/L IBA and 0.1 mg/L GA₃, B) MS medium without growth regulators and C) MS medium with reduced sucrose (10 g/L) and no growth regulators. After four weeks in culture, shoot moisture content (%) was determined, and cold hardiness (LT₅₀) was determined by controlled freezing of the plants and assessing the survival visually. Shoot moisture content was lowest on medium B. Growth regulators in the medium lowered the LT₅₀. Cold hardiness was not affected by the level of sucrose in the medium. Cold hardiness of the cultivars in vitro did not correspond to their relative hardiness in the field. Presumably, cultivar differences in cold hardiness are only revealed after acclimation. Further study is required to determine the appropriate acclimation procedure for screening strawberry cold hardiness in vitro.
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