Evaluation of Morphological Variation and Path Coefficient Analysis of Oil Content of Thymus daenensis Celak Populations

Thymus daenensis Celak is one of the most important medicinal plants and endemic species in Iran which has a large dispersion and wide distribution in the highlands of the Zagros Mountains. In this study, diversity of morphological traits and oil content (w/w) was evaluated among and within six natural habitats with diverse climates (Mehran, Bijar, Shekarnab, Ghateralan, Ghiagh and Semirom) .Beside, factors affecting on essential oil yield were determined by path coefficients analysis. The results indicated significant variation among populations for morphological traits. Cluster analysis divided individual plants into four independent groups corresponding to their geographical origin. The mean oil content was varied between 1.53-4.28% among populations. Path coefficient analysis showed that, among studied traits, inflorescences length and leaf length had highest direct effect while, bract length and plant height had highest indirect effect on the percentage of oil. Finally among the studied populations, population of Ilamis was suitable to be used in breeding and domestication programs due to good growth performance, adaptability to stress conditions and within population variation.