A survey of cold hardiness in some olive (Olea europaea L.) cultivars

In order to study cold hardiness in olive trees, this experiment was conducted on one-year-old olive plants cvs. 'Zard', 'Roghani', (two Iranian native cultivars) 'Mission' and 'Koronieki' (two foreign cultivars) during 2001-2002. The experiment was carried out at two different stages of plant growth (acclimated and non-acclimated to cold hardiness). Soluble carbohydrates were measured in leaf extracts of plants from each treatment. Ionic leakage was measured from leaf tissues of plants exposed to artificial temperatures of 0, -4, -8, and -12 degrees C, by a cooling rate of 4 degrees C per hour. Results showed that the amount of soluble carbohydrates increased during fall because of internal physiological reactions related to cold acclimation in the plants. The amount of soluble carbohydrates in the native cultivars was higher than in the others. Based on ionic leakage during non-cold acclimated stage, cultivars could be hardy, semi hardy and sensitive to cold. More over the use of lower temperatures especially during cold acclimation phase will help us to get certain results.