Background: Rosemary is a medicinal plant exhibiting potential for natural antioxidants.

Materials and Methods: In a glasshouse (soil culture) experiment, the effect of salt stress and copper nutrition on growth and essential oil of rosemary was investigated. Uniform cuttings of rosemary were exposed to three salinity levels (0, 50 and 100 mM NaCl) and two copper concentrations (0, 5 mg Cu kg-1 soil).

Results: Salinity and Cu nutrition had a significant effect on the growth of rosemary. By increasing salinity of irrigation water from 0 to 50 and 100 mM NaCl, the growth of rosemary was decreased by 7% and 11%, respectively. The slight reduction in the growth of rosemary even at the highest salinity level (100 mM NaCl) indicating that rosemary is a relative salt-tolerant plant (Threshold EC= 8.0 dS m-1). Copper nutrition partly alleviated adverse effect of low and medium salinity levels (0 and 50 mM NaCl) on growth of rosemary. The results show that Cu nutrition improves or accelerates the adaptation of rosemary to salt stress. The interaction of salinity and Cu resulted in a significant increase in essential oil content of rosemary. Moderate salinity level (50 mM NaCl) induced a significant increase in essential oil content of rosemary. However, exposure of rosemary plants to 100 mM NaCl did not change essential oil content. At 0 and 50 mM NaCl treatment, oil content of rosemary was influenced by Cu while it remained unchanged at 100 mM NaCl.

Conclusion: According to the results of the study, Cu had a positive impact on rosemary salt tolerance and its secondary metabolites production.