Abstract:Using detached leaves of three Olea europaea varieties (‘Gordal’,‘Chenggu 32’ and ‘Frantoio’) as experimental materials,we determined their physiological and biochemical indexes,to explore the mechanism on drought resistance of different olive varieties under 30% PEG stress.The results showed that:(1)With the time of osmotic stress prolonged,the water and chlorophyll contents in detached leaves of different olive varieties decreased,while the relative electrolytic leakage and MDA content increased significantly.The result indicated that,the osmotic stress caused deterioration of water conditions,decomposition of chlorophyll,aggravation of lipid peroxidation and damage of cell membrane of the leaves;meanwhile,relative content of bound water and free water,O-·2 producing rate,SOD activity and regulatory substances in leaves of three olive varieties showed a rising trend.(2)Inter-species comparison,with the time of osmotic stress prolonged,MDA content of ‘Frantoio’ leaves was lower than that of ‘Gordal’ and higher than that of ‘Chenggu 32’.In the same period,changes on the contents of bound water and free water,superoxide anion production rate,SOD activity in different species leaves showed similar performance.In conclusion,the results indicated that the drought resistance of the three olive varieties was ‘Chenggu 32’>‘Frantoio’>‘Gordal’;furthermore,higher ratio of bound water content/free water content,less O-·2 producing rate,higher SOD activity and more regulatory substances of ‘Chenggu 32’ under the osmotic stress can guarante the leaves of ‘Chenggu 32’ had the strongest ability of osmoregulation and the strongest ability to endure dehydration and lipid-peroxidation under the osmotic stress,so the drought resistance of ‘Chenggu 32’ was better than that of ‘Gordal’ and ‘Frantoio’.