Study of quality and quantity of essential oil of Thyme species cultivated in national botanic garden of Iran

In order to investigate the quality and quantity of essential oil of Thymus species, an experiment was conducted under field condition at Research Institute of Forests and Rangelands. This project was related to national project, entitled extraction, qualitative and quantitative analyses of the essential oil of different Thymus species in some provinces of Iran. For This purpose, seeds of 75 accessions, collected from various provinces, were cultivated under greenhouse condition. Then, seedlings were transferred to the experimental field and cultivated under field condition. Flowering shoots were collected at 50% of flowering stage, dried in shadow and grinded. Essential oil extraction was carried out by hydro distillation method (Clevenger apparatus-Britain pharmacopeia) for three hours. Chemical compounds were identified with GC and GC-MS. According to the results, essential oil yield was between 0.04%-2%. The highest essential oil yield in relation to dry weight belongs to T. kotschyanus (2%), T. daenesis (1.92%) and T. vulgaris (1.69%) from west Azerbaijan province, Lorestan province and Markazi province, respectively. Linalool, geraniol, α-terpineol, Thymol, carvacrol, α-terpinyl acetate and geranyl acetate chemotypes were recognized among accessions. During two years, the highest Thymol (76.6%), carvacrol (82.9%) and geraniol (62.7%) were observed in T. daenesis from Markazi province, T. daenesis from Semnan province and T. lancifolius from Fars province.