Effects of cultivation and domestication on a number of Thymus species in different climatic condition of Iran

To investigate natural habitat and the effects of cultivation and domestication of Thyme species in agro ecosystems, series of experiments were carried out in West Azarbaijan, Esfahan, Tehran, North Khorasan and Ghazvin provinces during 2007-2011. Following the determination of natural habitats for Thyme species in the provinces and selection of the sites, ecological, geological and topographical characteristics of each site were studied. Some plant characteristics were recorded in 9 plots of 5*5 m2 in each site. Extraction of the shoot essential oil in the plots were conducted by cleavenger system. The results showed that, thymol, carvacrol and a number of components were the majer components in the essential oil of Thyme species. Thymol and 1,8 sineol were observed in all of the mentioned species. In most species, thymol was the major component compared to the others. The highest thymol content was obtained from Th. daenensis samples in Eskandary region in Esfahan province that contained 71.8 percent of the components in the essential oil. The lowest amount of thymol was observed in Th. carmanicus samples from Khansar region in Esfahan province that contained one percent thymol and 90 percent carvacrol. This sample had the highest carvarol content in comparison with others. In the second phase, seed and graft collected from the habitats were planted in the field condition and effects of domestication and cultivation practices were investigated on Thyme species at field condition of the provinces. The experiment was conducted as split plot in a randomized complete blocks design with three replications. The main treatment included a number of local Thyme species and Thymus vulgaris as a domestic cultivar and sub plots were different harvest stages of Thyme species. Among all Thyme species cultivated in 2007 in the provinces, maximum arial parts dry matter accumulation was obtained from the seeds of Th. daenensis in Shahid Fozveh station in Esfahan province. Dry matter yield in full flowering and ripening stages were 4347.46 and 4423.88 kg/ha respectively with a significant difference compared to the others. The among of essential oil in above stages were 2.07 and .0.89 percent respectively. Investigation of thymol variation among local species in the field condition, showed the highest thymol amount in Th. daenensis from Shahid fozveh station in Esfahan province and Th. transcaspicus from Kohnekand station in North Khorasan with 81.24 and 74.44 percent respectively. Thymol amount in Th. vulgaris as a domesticated control specie, in Saatloo station in West Azarbaijan, Shahid Fozveh station in Esfahan, Khojir station in Tehran and Kohnekand station in North Khorasan provinces were 48.97, 63.05, 42.24 and 74.44 percent respectively. Based on the results, Th. daenensis as a local specie with an optimal performance in terms of arial parts yield and thymol amount compared to Th. vulgaris and other species.