Comparing herbal yield, essential oil content and composition of anis hyssop (Agastache foeniculum Kuntze) in field and greenhouse conditions under drought stress

Anise hyssop (Agastache foeniculum Kuntze) is a prennial herb plant belonging to the Lamiaceae family. The Essential oil form this plant is used in food, pharmaceutical, cosmetics industries, and flavoring liqueurs. To evaluate the effect of drought treatments on essential oil content and composition of anise hyssop, an experiment was conducted in a Randomized Complete Blocks Design (RCBD) with seven water stress treatments and three replications in two field and greenhouse conditions. The treatments were 100% of field capacity (FC), 85% of FC, 70% of FC, 55% of FC, 100-85% of FC (100% at vegetative and 85% at reproductive period), 100-70% of FC (100% at vegetative and 70% at reproductive stage), 85-100 % of FC (85% at vegetative and 100% at reproductive phase). A Clevenger-type apparatus (hydro distillation) was used to extract the essential oils from the plants foliage. Essential oil components were analyzed and recognized by GC and GC/MS. The result showed that the highest (2.30%) and lowest (1.64%) amounts of essential oil content were observed at 55% FC and 100-70% FC in the field condition, respectively. Water stress also caused increase in the essential oil content in the greenhouse condition. Accordingly, the essential oil content was increased from 1.12 in 100% FC to 1.62 in 55% FC. Herbal yield and essential oil yield were significantly decreased with the progressing level of water deficit in both field and greenhouse conditions. Methyl chavicol was the main composition of essential oil in the two conditions and unaffected by water stress. In total, 85-100 % FC and 100 % FC were recommended to field and greenhouse conditions, respectively.