Freezing Stress on Lipid Peroxidation and Antioxidant Enzyme Activities of Olive cvs. ‘Fishomi’ and ‘Roughani’

Changes in freezing injury percentage, lipid peroxidation (malonaldehyde formation), antioxidant enzymes activity and proline content were monitored in the leaves of olive cvs. ‘Fishomi’ and ‘Roughani’ under diff erent freezing temperatures (-5, -10, -15 and -20°C for 10 h). Th e results showed that freezing injury (determined by electrolyte leakage analysis) and malonaldehyde (MDA) content of cv. ‘Fishomi’ were signifi cantly lower than of cv. ‘Roughani’ ones. Th e activities of peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) and polyphenol oxidase (PPO) enzymes of cv. ‘Fishomi’ were signifi cantly higher than those of cv. ‘Roughani’. However, superoxide dismutase (SOD) activity of cv. ‘Roughani’ was higher than of cv. ‘Fishomi’. Th e proline accumulated in leaves of cv. ‘Fishomi’ was signifi cantly higher than of cv. ‘Roughani’ during freezing stress. Th e results demonstrated that freezing injury percentage was positively correlated with ion leakage percentage and MDA content in both cultivars. In contrast, SOD, APX and CAT activities and also proline content were negatively correlated with freezing injury percentage. Th ere was a signifi cant negative correlation between PPO activity and freezing injury in cv. ‘Fishomi’. It can be concluded that the lower freezing injury percentage, ion leakage, and MDA content followed by the higher antioxidant enzyme activates as well as proline content in cv. ‘Fishomi’ is a consequence of more eff ective protective mechanisms.