Background: Biosynthesis and metabolism of phytochemicals in medicinal and aromatic plants are vigorously affected by different abiotic elicitors including chemicals.

Objective: This experiment was designed to investigate the effects of three levels of copper sulfate (Cu: 0, 5, 25 mg kg^-1) and zinc sulfate (Zn: 0, 10, 50 mg kg^-1) and their combinations on yield, chemical compositions of essential oil and metals accumulation in sweet basil (Ocimum basilicum L.).

Methods: The amount of employed metals dissolved in 200 ml distilled water and sprayed over each pot, layer by layer as evenly as possible. Physical and chemical properties and concentration of the elements in soil samples were measured. The essential oil was isolated by hydro-distillation and analyzed by GS and GS-MS technique.

Results: Results showed that the dry weight of root, shoot and essential oil yield were increased in treatments of Cu₀Zn₁₀, Cu₅Zn₀ and Cu₅Zn_10, as compared to control. The increase of Zn levels in soil enhanced the concentration of Zn in shoot and root of plant when compared to control. Also, Zn and Cu antagonized the uptake of together at the high levels. Root tissues always showed greater concentration of both Cu and Zn than those of shoot. The content of linalool and methyl chavicol was significantly increased by application of employed metals in comparison to control plants.

Conclusion: Findings indicate that the growth and essential oil yield of O. basilicum was significantly enhanced by application of low levels of Cu and Zn. However, the highest levels of Cu and Zn were accumulated in root, without significant reduction in growth and biomass values.