Essential oil Content and Composition of Dracocephalum Moldavica under Different Irrigation Regimes

Dracocephalum moldavica l. is an annual species of lamiacea family whose essential oil is widely used in medicinal, food, cosmetic and health industries. drought stress is a major factor limiting plants growth and yield. the main objective of this study was to evaluate the influence of irrigation regime on essential oil content and composition of d. moldavica l. the irrigation regimes were 100%, 85%, 75% and 55% of field capacity (fc). the results showed that 53 essential oil components were identified in different irrigation regimes. thirty-six, twenty-two, twenty and thirty components were identified at 100%, 85%, 75% and 55% of fc, respectively. the amounts of identified components were 99.4%, 96.6%, 97.8% and 99.9% at 100%, 85%, 75% and 55% of fc, respectively. the highest of main components were geranyl acetate, geraniol and geranial in all the irrigation regimes. the amount of oxygen-containing monoterpenes of essential oil were 81.6%, 94.5%, 91.8% and 92.0% at 100%, 85%, 75% and 55% of fc, respectively. our results showed that essential oil content increased significantly by 3.4%, 13.8% and 27.6% at 85%, 75% and 55% of fc, respectively. furthermore, the amount of oxygen-containing monoterpenes of d. moldavicum increased by 15.8%, 12.5% and 12.7% at 85%, 75% and 55% of fc, respectively, but oxygen- containing sesquiterpenes decreased by increasing the level of drought. in conclusion, our results indicated the advantage of drought for increasing essential oil content and oxygen-containing monoterpenes (om), especially geranyl acetate, geraniol and geranial in d. moldavica.