Study on drug yield and essential oil content and composition of Thymus daenensis Celak. under cultivated condition

Thymus daenensis Celak. is distributed in some areas of Iran such as Qazvin province. In order to evaluate essential oil yield and composition of T. daenensis an experiment was conducted in research farm of Qazvin Research Station based on randomized complete block design with three replications during 2006-2008. Aerial parts of the plants were dried in shadow and hydro distilled for obtaining their essential oils. Capillary GC and GC/MS analysis were used to determine the volatile profile of the essential oil samples. Fresh and dry herbage yields of T. daenensis were 9124-1568, 10250-2176 and 11337-2750 kg/ha in 2006, 2007 and 2008 respectively. Aerial parts yield were higher in the first cutting and showed decreased trend in latter cutting each year. The yields of fresh and dry biomass were 3498-800 kg/ha for the first cutting, 3015-720 kg/ha for the second cutting, 1947-508 kg/ha for the third cutting and 1976-504 kg/ha for the forth cutting. There was no difference in volatile oil percentage in different years, but there were significant difference between different cuttings. The oil yield was 2.83% at third cutting and 3.07% at first cutting. Thymol, γ-terpinene, ρ-cemene, metyl-eyther carvacrol and carvacrol were the main components of essential oil in all cuttings and years. Thymol percentage was varied from 69% (first cutting) to 76% (second cutting) in the essential oils of T. daenensis.