Comparison on quality and quantity in essential oils of six species of Thymus L. in Yazd province

Thymus belongs to Lamiaceae family and consist over 215 different Species throughout the world. Eighteen species grow naturally in Iran of which four species are endemic. Then cultivate of 6 species of Thymus including: Thymus kotschyanus,T. fedchenkoi, T. lancifolius, T. pubescens, T. daenensis and T. migricus in station of medicinal plants. Research in Shahedieh Yazd in 2008, with the coordinates of Longitude and Latitude 55 31 49 northly, 21 15 54 east to heigh of 1210 meters above sea level. The aerial parts of plants were collected before and full flowering stages and then were dried in shadow and hydro-distilled for obtaining their essential oil. Analysis and identification of chemical composition of the oil were performed by GC and GC/MS. That determined the best time to harvest with regard to oil yield and oil production is flowering time. The highest amount of oil yield was related to species Thymus daenensis (3/52%). The highest amount of oil production was related to species T.lancifolius (20.88Kg/ha). Maximum composition of essential oil at full flowering para-cymene, 1,8-cineol, gamma-terpinene and carvacrol, respectively 11.19%, 12.14%, 10.74 was related to T. fedchenkoi and highest of borneol 12.7% wasreleted to T. pubescens,and heghiest of thymol 73.26% was releted to T. daenensis and highiest of number compound 25 was releted to T. pubsens and T. lancifolius. The highest amount of oil yield (before flowering) 2.36% was related to T. daenensis and highest amount of oil production was related to species T. fedchekoi 10.03 Kg/ha. and highest carvacroi, thymol, borneol, gamma terpinene, cineole and para-cymene respectively 62.7%, 69.4%, 14.41%, 8.41%, 8.48% and 11.94% were related to respectively T. kotschyanus, T. lancifolius, T. fedchekoi, T. fedchekoi, T. pubsens, T. migricus and highest of number compound 25 was related to T. fedchekoi. Generally with regard oil yield and oil production and highest amount of thymol T. daenensis was selected as superior species.