Study on effect of some environmental factors on morphological traits and essential oil productivity of Thymus caramanicus Jalas

Thymus caramanicus Jalas is belonging to family Lamiaceae. Among 250 species of this genus with a worldwide distribution, 14 species grow naturally in Iran. Thymus caramanicus Jalas is one of the endemic species which has distribution in central Iran. In this study, natural habitats of the species were identified in different regions of Kerman, Esfahan and Semnan provinces in 2010.Ten complete plants at flowering stage were collected from seven localities in order to study and evaluate the morphological characters. Flowering stems were used to extract essential oil. Characteristics associated with each habitat were recorded and three soil samples from each site were taken to evaluate soil physical and chemical properties. Vegetative and reproductive characteristics of each population and the essential oil of the studied species in each habitat were recorded. Results were analyzed using cluster analysis method with SPSS software and correlation between evaluated traits and essential oil productivity were determined. Populations were clustered in two groups based on all studied characters. Populations collected from Kerman and Esfahan provinces were located in a same group and populations from Semnan province were placed in an independent group. Differences between these two groups may be from different climates in their habitats and their adaptation to the different environmental factors. According to the results, the best vegetative and also reproductive characters such as flowering stem length, leaf length and width, number of flowers per inflorescence and corolla length and also the highest essential oil production (2-3%) were recorded for specimens from Kerman province; therefore, it is recommended for breeding programs or cultivation.