Study of morphological characteristics and essential oil of different populations of Achillea wilhelmsii C. Koch

One of the most important methods of conservation and survival of plants in nature is the cultivation and domestication of plant species to select the best population. According to the necessity of cultivating and domesticating medicinal plants, in this research, 22 accessions of Achillea wilhelmsii C. Koch were planted and evaluated in the Alborz Research Station, Research Institute of Forests and Rangelands. This research was performed in a randomized complete block design during 2013-2015. In order to study and compare the morphological characteristics of different accessions of this plant, the plant height, canopy cover, number of main stems, number of capitol per plant, number of florets in capitol, plant fresh and dry weight, and essential oil content were measured at 50% flowering. The extraction was carried out by water distillation method with Clevenger. Analysis of variance and mean comparison showed that the difference among the accessions was significant at 1% level. The results showed that Saqez 1 had the highest plant height, plant dry weight, number of capitol and florets and essential oil content. The correlation between the study characteristics was significant at 1% level; however, no significant correlation was found between essential oil content and other characteristics except for the number of capitol. Using the principal component analysis, the first five components explained 99% of the total variance of the variables. Canopy cover, plant height, number of stems, number of capitol, and plant fresh and dry weight, with a positive coefficient, had the most important role in explaining the first component and explained 75% of the variance of the variables. In the cluster analysis, the accessions were divided into three groups, and the Saqez1 accession was placed in a separate cluster as an indicator.