The experiment was aimed to evaluate the effects of water deficit stress on the drug yield, essential oil content and composition and antioxidant enzymes activity of Tarragon. The results showed that the impact of drought stress and the interactive effects of drought stress and accessions on the activity of superoxide dismutase, catalase, ascorbate peroxidase, guaiacol peroxidase, proline, drug yield and essential oil yield (only in second year) were significant. Our findings showed that water deficit increased the essential oil content in both years, while decreased the essential oil and drug yield. Estragole (up to 88.39 %), Z-β-ocimene (up to 7.81 %), Eβ-ocimene (up to 5.84 %), terpinolene (up to 4.92 %), limonene (up to 3.32 %), methyl eugenol (up to 2.59 %) and α-pinene (up to 1.3 %) were identified as the major components of essential oil in the most of studied plants. However, there were variations among the different accessions in terms of essential oil components. Water deficit led to a change in the quality and quantity of essential oil, which were not the same in different plants. In some genotypes, the content of some essential oil components in Tarragon had the highest values under severe water deficit stress. Based on the results of drought tolerance indicators and essential oil yield assay, Estahbanat and Hamadan in the first year and Varamin and Kermanshah in the second year were selected as drought-tolerant accessions. Given the wide variety of Tarragon genotypes in response to drought stress in terms of traits studied, these local accessions appear to have good potential to be used as raw materials in breeding programs. So that using them in breeding programs is a proper shortcut to achieve the intended target, especially in screening programs.
