Comparison of mid-winter cold-hardiness by electrolyte leakage in shoots of 15 grape cultivars

The cold-hardiness of 15 grapevine cultivars was compared in mid-winter (January 2016). The level of cold-hardiness was determined by measuring electrolyte leakage at various freezing temperatures and was expressed as LT₅₀, the temperature at which the incidence of injury reached 50%, and as T_max, the temperature at which the rate of injury was maximal. The LT₅₀ and T_max values for the 15 grape cultivars ranged from -21.9±0.08°C to -38.3±0.13°C and from -12.1±0.05°C to -28.2±0.12°C, respectively. T_max values were significantly positively correlated with LT₅₀ values (r=0.90*, P≤0.01). On the basis of their levels of cold-hardiness in terms of LT₅₀ values, the 15 grape cultivars were ranked in the following order: 'Saemaru' › 'Tano Red' › 'Jinok' › 'Shiny Star' › 'Campbell Early' › 'Italia' › 'Hongsodam' › 'Suok' › 'Heukgoosul' › 'Himrod' › 'Heukboseok' › 'Shine Muscat' › 'Kyoho' › 'Hongju Seedless' › 'Perlon'. Similarly, on the basis of their levels of cold-hardiness in terms of T_max values, the 15 grape cultivars were ranked in the following order: 'Shiny Star' › 'Campbell Early' › 'Hongsodam' › 'Italia' › 'Heukgoosul' › 'Suok' › 'Saemaru' › 'Himrod' › 'Heukboseok' › 'Jinok' › 'Kyoho' › 'Shine Muscat' › 'Tano Red' › 'Hongju Seedless' › 'Perlon'. These results will be useful as practical information for breeding and cultivation of grapevines in Korea.