Zahra Azimzadeh - Department of Horticultural Science,
Abbas Hassani - Department of Horticultural Science,
Babak Abdollahi Mandoulakani - Department of Plant Production and Genetics
Ebrahim Sepehr - Department of Soil Science, Faculty of Agriculture, Urmia University.

Oregano (Origanum vulgare L.) is a perennial herbaceous plant belonging to the Lamiaceae family which has many uses in folk medicine and pharmaceutical, food and cosmetics industries. Oregano has antibacterial, antifungal, antiviral and antioxidant properties due to its biologically active compounds such as phenols. Iran is located in arid and semi-arid region, so the soil and irrigation water salinity has become a major challenge in the country. Since the biosynthesis of secondary metabolites is strongly affected by environmental stresses such as salinity, so this study was conducted to investigate the effect of salinity stress on physiological and phytochemical characteristics of oregano in a completely randomized design with three replications. The experimental treatments included salinity stress induced by sodium chloride at four levels (۰, ۲۵, ۵۰ and ۱۰۰ mM) which were applied until flowering stage. The results showed that chlorophyll content (SPAD) decreased but proline and total phenol content and antioxidant activity of leaves increased as the salinity stress intensified. Furthermore, the lowest level of salt stress (۲۵ mM) increased the essential oil content and total soluble sugars. According to the results of this study, it can be concluded that the cultivation of oregano in soils with moderate salinity can be important due to the increase of its secondary metabolites.

Antioxidant activity, Chlorophyll, Essential oil content, NaCl salinity, Proline