Quality and quantity yield of thyme essential oil in different climatic conditions

The use of thyme as an edible plant and spice has been commonplace since ancient times. Flowering shoots are used in this plant. The essential oil of thymus species has antimicrobial and antioxidant properties. In this study, 75 populations of thymus species were cultivated from the research fields of East Azarbaijan, Ardebil, Isfahan, Khorasan Razavi, Zanjan, Semnan, Fars, Qom, Golestan, Markazi, Homand and Absard, Hamedan, and Yazd as well as National Botanical Garden of Iran. The quality and quantity yield of essential oil was investigated. Chemical compounds of the study essential oils were identified with GC and GC-MS. The essential oil yield of the study populations was calculated to be 0.15%-4.52% (dry weight). The highest essential oil yield (4.52%) was recorded for T. fedtschenkoi of West Azarbaijan origin, cultivated in Golestan province. The highest percentage of thymol (79.63%) was recorded for T. transcaspicus of Yazd origin and T. daenensis of Lorestan origin. The highest percentage of carvacrol (86.7%) was identified in T.transcaspicus cultivated in the HomandAbsard Station. The highest percentage of geraniol (77%) was identified in T.kotschyanus cultivated in Yazd province. Results showed that if the quantity (essential oil percentage) is considered, T. fedtschenkoi from West Azarbaijan province could be recommended for mass cultivation and in the case of thymol and carvacrol, T. transcaspicus from Yazd province is recommended. However, if geraniol is important, T. kotschyanus from Kurdistan could be a better suggestion.