engleski

Differential Response of Superoxide Dismutase Activity of Two Olive Cultivars to Increased Salinity and its Relation to Growth and Ion Content

The olive (Olea europaea L.) is considered moderately tolerant to salinity with clear differences found among cultivars. One-year old self-rooted olive plants of the Croatian cultivar Oblica and Italian cultivar Leccino were grown for 90 days in nutrient solutions containing 0, 66 or 166 mM NaCl, respectively. The shoot length and the number of nodes and leaves for both cultivars were not affected by salinity up to 66 mM NaCl, however at 166 mM NaCl growth of ‘ Leccino’ was reduced earlier and to a higher extent than the growth of ‘ Oblica’ . After 10 days of exposure to 66 and 166 mM NaCl, increased activity of superoxide dismutase (SOD) was observed in ‘ Leccino’ , whereas there was almost no response in ‘ Oblica’ . Suppressed SOD activity in ‘ Leccino’ at 166 mM NaCl was observed after prolonged stress (90 days), whereas in ‘ Oblica’ SOD was increased at 66 mM compared to control or 166 mM NaCl. Electrolyte and K+ leakage were increased and relative water content decreased as NaCl concentration increased with similar intensity of response measured in both cultivars. ‘ Oblica’ exhibited an ability to keep a higher K+:Na+ ratio at all salinity levels compared to ‘ Leccino’ , but since no difference was found in leaf K+ concentration this was mainly achieved by less Na+ ions reaching the young leaves. The antioxidative system represents a component of the complex olive salt tolerance mechanism and it seems that role of SOD in protection from oxidative stress depends on NaCl concentration, duration of exposure and cultivar.

Superoxide Dismutase; salt tolerance; oxidative stress

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