Physiological and antioxidant response of three cultivars of cucumber (Cucumis sativus L.) to salinity

The effects of salinity on the growth, relative water content (RWC), chlorophyll content, inorganic ions, prolineaccumulation, lipid peroxidation and antioxidant enzymes, superoxide dismutase (SOD), ascorbate peroxidase (APOX),and catalase (CAT) of 3 cucumber (Cucumis sativus L.) cultivars (Çengelköy, Anadolu F1, and Beith Alpha) wereinvestigated. Cucumber cultivars were grown in perlite culture and irrigated with half-strength Hoagland nutrientsolution for a period of 35 days under controlled conditions. After this period, seedlings were treated with 150 mM NaClsolution and the plants were harvested on day 7 and day 14 of salt treatment. The fresh and dry weights, RWC, inorganic ions, total chlorophyll, proline and malondialdehyde (MDA) content, and SOD, CAT, and APOX activities were determined. In general, the applied salinity affected all of the considered parameters depending on the duration of salt treatment and the cultivars analyzed. Proline content also increased with salinity, but accumulation of proline was lower in Çengelköy than in the other cultivars. The results suggest that the protection mechanism against oxidative damage due to induced activity of antioxidant enzymes may be better in Çengelköy than in Beith Alpha or Anadolu F1. The higher K+ concentrations, RWC, total chlorophyll content, and SOD, CAT, and APOX activities, together with the lower MDA, proline content, and Na+ and Cl– concentrations detected in Çengelköy might make this cultivar more salt-tolerant than Beith Alpha or Anadolu F1.