Sedghali Zamani - East Azarbaijan Agricultural and Natural Resources Research Center, East Azarbaijan, Iran
Mohammad Taher Nezami - Karaj Branch, Islamic Azad University, Karaj, Iran
Ahmad Bybordi - East Azarbaijan Agricultural and Natural Resources Research Center, East Azarbaijan, Iran
Maryam Behdad - Department of Horticulture, Khorasgan (Isfahan)Branch, Islamic Azad University, Isfahan, Iran

To evaluate the effect of different levels of salinity on antioxidant enzymes activity of leaves and plantphysiological characteristics of canola as a marker of resistance to salinity, an experiment wasconducted in greenhouse of Research Center of Agriculture and Natural resources in East Azarbaijanin 2009. Treatments included combinations of five different levels of salinity (0, 50, 100, 150, and 200mM) and four cultivars of brassica included (Elite, Licord, SLM046 and Okapi). With increasingsalinity, stomatal conductivity, transpiration and leaf relative water decreased in all cultivars. Effect ofsalt stress on antioxidant enzymes of leaves was significant, and changes in the amount of superoxided dismutase enzymes, catalase and glutathion reductase was observed. Enzyme activity in theperiod of growth increased and in plant maturity decreased. Comparison between canola cultivarsshowed the strong correlation between leaf relative water and enzyme super oxide dismutase activity.SLM046 showed the least changes in leaf relative water level and the highest enzyme activity and wasresistant cultivar and Elite were the most sensitive cultivar to salinity.

Antioxidant enzymes, Salinity, Relative water, Canola