The Impact of Macro Environmental Factors on Essential Oils of Oliveria decumbens Vent. from Different Regions of Iran

background: environmental factors may affect qualitative and quantitative properties of essential oil in medicinal plants. objectives: the aim of the present study was to determine the effect of macro environmental factors on essential oils content and composition of iranian populations of oliveria decumbens. methods: the aerial parts of 25 wild populations of oliveria decumbens vent. were collected from various natural habitats in the southwest of iran. the essential oil of samples was analyzed by gas chromatography (gc) and gas chromatography-mass spectroscopy (gc-ms). therefore, macro environmental factors were determined by the pca method. the correlations between the factors were calculated based on the pearson correlation coefficient. results: the major compounds of essential oils were thymol, carvacrol, p-cymene, and y-terpinene, respectively, with an average of 28.77%, 25.31%, 14.02%, and 8.12%. the results showed that the altitude, mean evaporative per month (mem) and mean day temperature (mdt) were effective macro environmental factors on essential oil, thymol, and carvacrol content. conclusions: the highest content of essential oil, thymol, and carvacrol was related to warm and semi-humid regions.