EVALUATION OF ELECTROLYTE LEAKAGE FOR DETECTING COLD ACCLIMATIZATION IN SIX DECIDUOUS TREE SPECIES

Dormant and cold acclimated forest seedlings have a higher stress tolerance after lifting and support longer storage periods without loss of plant vitality and vigour. As dormancy is induced by photoperiod cold acclimatization needs lower temperatures. Cold acclimatization in temperate woody plants is linked to metabolic changes such as an increase of soluble sugars - especially of the oligosaccharides raffinose and stachyose - in bark tissue and in buds. Yet this is a laborious technique for routine analysis of cold acclimatization. Therefore the possibility of electrolyte leakage (EL) to detect cold acclimatization was investigated for six deciduous tree species namely Acer pseudoplatanus, Crataegus monogyna, Fraxinus excelsior, Prunus avium, Quercus rubra and Tilia cordata. As a measure of cold acclimatization or frost hardiness, bud damage following controlled freezing to -18°C and -25°C respectively was assessed. The EL_-18°C and EL_-25°C were correlated with raffinose and stachyose concentrations in the buds. Good correlations were only found for three species. The potential of measuring cold acclimatization by electrolyte leakage is species dependant.