Levisticum officinale Koch is one of the most important plants producing essential oil. An experiment was conducted to determine the effect of drought stress on growth, total protein and essential oil content of L. officinale. The experiment was conducted in a greenhouse, in a completely randomized design using five replications. Aridity levels of field capacity irrigation (as control), ¡0.6 and ¡1.0 MPa were applied. There was a significant effect of aridity on the leaf area in L. officinale. The highest leaf area values were found in the lowest aridity (FC) level. The root weight and root length in the¡0.6MPa aridity level were more than that of the control aridity level, but shoot height and shoot weight were highest in the control treatment. The total soluble protein content under ¡0.6 MPa drought stress was numerically lower than that in the control treatment, but statistically there was no significant difference between protein contents in the ¡0.6 MPa and the control treatment. Compared to the control treatment, the total soluble protein content of L. officinale significantly decreased in the ¡1.0 MPa drought treatment. The essential oil content of L. officinale was significantly increased in the ¡0.6 MPa drought treatment compared to the control. Compared to control treatment, a significant reduction was found in essential oil content of L. officinale in the ¡1.0 MPa aridity treatment. The results suggest that in the drought levels between ¡0.6 and ¡1.0 MPa, L. officinale could be used for arid and semi-arid lands economical use.
