Influence of some environmental factors on the essential oil variability of Thymus migricus

Essential oils of the air-dried aerial parts of five populations of Thymus migricus Klokov & Desj.-Shost. collected from northwest Iran were obtained by hydrodistillation with yield of 1.1 - 3.3% (w/w). The essential oils were analyzed by a combination of GC-FID and GC-MS techniques, to check for chemical variability. According to populations, twenty-nine components, representing 97.3 - 99.3% of the total components, were identified. Oxygenated monoterpenes were the main group of constituents in all samples (65.2 - 78.5%). Thymol (46.6 - 72.5%), gamma-terpinene (6.2 - 16.7%), p-cymene (4.0 - 6.5%), n-hexadecanol (0.4 - 6.5%), geraniol (0.5 - 4.7%), limonene (0.0 - 3.5%) and carvacrol (0.5 - 3.4%) represented the major compounds. Two chemotypes were identified: thymol and thymol/linalool. In addition, canonical correlation analysis between some essential oil characters and some environmental factors revealed a significant relationship between oil components and environmental factors. The influence of environmental factors over p-cymene, gamma-terpinene, linalool and thymol was evident. Essential oil yield was fairly strongly related to the concentrations of Ca2+ and K+, percentage of organic matter, altitude, temperature, and soil texture.