Changes of physiological status during cold storage of in vitro cultivated plants

In vitro storage of shoot cultures of 9 sour cherry and 5 raspberry genotypes at 5°C was applied. The effect of low temperature on shoot growth and viability in relation to BA and sucrose concentration in the medium was investigated. During low temperature storage cherry and raspberry cultures were affected by BA and sucrose concentrations in the medium. The best storage conditions were adaptation in a culture room for 2 weeks before subjecting cultures to low temperature and supplying with 0.25 or 0.5 mg l^-1 BA and 40 or 60 g l^-1sucrose. Eight sour cherry cultivars cultivated on optimal medium for a year of cold storage developed roots and revealed excellent survival and differences in growth according to each individual genotype. Raspberry 'Ariadne' shoot cultures were successfully stored at 5°C for 2 years and cherry P-HL-A shoot cultures for 3 years without adding any nutrient medium and without affecting shoot proliferation ability. During the initial period of storage, peroxidase and polyphenol oxidase activities in shoots were oscillating. Increase of enzyme activities coincided with formation of axillary shoots. After a year of cold storage with 60 g l^-1 sucrose in the medium, shoot peroxidase activity was lower than with 30 g l^-1 sucrose and than in shoots at 25°C. These results suggest that sucrose has some metabolism stabilisation role in low temperature stress conditions.