Evaluation of Freezing Tolerance in Some Olive Cultivars in Fars Province

Selecting frost tolerant cultivars and understanding the mechanisms of frost tolerance¡ can greatly reduce the amount of frost damage to the olives. Although the olive tree is classified among the most frost-hardy of the subtropical fruit trees¡ olive cultivars may differ in frost tolerance due to the differential survival of their specific organs. The purpose of this study was screening of different Olive cultivars for frost tolerance by means of ion leakage¡ potassium ion leakage¡ and amount of starch¡ soluble sugars¡ proline¡ and phenol in the separated leaves. In this experiment¡ leaf materials were exposed to frost temperatures (0¡ -3¡ -6¡ -12 and -15°C) for one hour and then several factors were measured. Results indicated that „Zard‟ and „Dehghan‟ possess the highest amount of soluble sugars¡ proline¡ phenolic contents and the lowest starch contents¡ ion leakage and potassium ion leakage percentage. In conclution¡ Zard and Dehghan cultivars were the most resistant cultivars and Drak¡ Dakal and Shiraz were the most sensitive cultivars to freezing in the range of investigated temperatures.