Formation of cold hardiness in strawberry during early plant development stage

The possibility of screening cold resistant strawberry seedlings in vitro has been investigated. It has been established that full autonomy of strawberry embryos is reached on 24-26nd day after pollination, when embryo length is not less than 75-80% of maximal length. Plant growth is best when plants are regenerated from embryos isolated on 26-30th day after pollination. Plants were considerably cold hardier when frozen in vitro 60 days after embryo isolation, than when frozen at 14 days. Strawberry seedlings not younger than 30 days are suitable for freezing and screening for cold hardiness in vitro. Cold hardiness of strawberry seedlings frozen in controlled conditions in vivo corresponds to cold hardiness of adult plants 90 days after seed germination. The correlation between cold hardiness of strawberry seedlings in vitro and in vivo was 0.83-0.89.