Impact of Exogenous Sucrose, Raffinose and Proline on Cold Acclimation of Strawberry In Vitro

The aim of this study was to evaluate the effect of sucrose, raffinose and proline additions on the growing medium aiming for increased cold hardiness of strawberry in vitro under conditions of insufficient cold acclimation. Increasing of sucrose addition to the growing medium from 3% to 6% decreased cold injury of 14 days cold acclimated strawberry microplants and increased the survival rate of microplants after freezing in vitro up to 30%. The effect of raffinose and proline additions in the growing medium to cold hardiness of strawberry in vitro was genotype dependent. Addition of raffinose and proline increased the survival rate of 14 days cold acclimated 'Elsanta' strawberry microplants, but did not change or decrease the survival rate of other tested cultivars - 'Melody, 'Venta' and 'Holiday' microplants. Under conditions of shorter cold acclimation duration (7 days) survival rate of 'Venta' microplants after freezing in vitro was lower than after 14 days acclimation, but the effect of different additions to the growing medium was higher. A higher amount of sucrose and proline had a positive impact on the survival rate of 'Venta' microplants. The impact of raffinose addition was negative.