Pimpinella anisum (anise) is one of the most important medicinal plants, which is used in drug industries. Drought stress, as a main abiotic stress, has a significant influence on growth and metabolic activities of medicinal plants species. In this study Pimpinella anisum was planted for the first time in Hamedan conditions with the aim of the evaluation of the effects of irrigation disruption on growth, essential oil content and essential oil yield of anise. Therefore, three irrigation treatments (irrigated plants till flowering stage, irrigated plants till seed filling stage, and irrigated plants till end of growing season as a control), were evaluated in a randomized complete block design (RCBD) with three replications. Results indicated that irrigation treatments had a significant effect on agronomic characteristics of anise. Irrigation disruption at the flowering stage significantly decreased, number of umbel per plant, number of seeds per umbelet, and seed yield as compared to control (full irrigated plants). Also, results indicated that anise seeds essential oil percentage was affected significantly by irrigation treatments.
