Medicinal plants have many applications in the treatment of humans, among which chamomile is one of the most valuable and widely used medicinal plants in the world. One of the most important breeding programs is the recognition of genetic diversity for the initial evaluation of plant masses. For this purpose, a study of genetic diversity and classification of experimental chamomile ecotypes was designed and implemented.

25 native and foreign ecotypes of chamomile were evaluated in a randomized complete block design with four replications in the research farm of German Pharmaplant. Some of these ecotypes were collected from their natural growing areas and some were chamomile cultivars. For this purpose, some morphological, phenological and essential traits were evaluated.

The results of analysis of variance showed that the difference between ecotypes in terms of all traits was significant at the level of 1% probability and showed great genetic diversity between traits. The results of phenotypic correlations and comparison of the mean of the studied traits showed that the traits of essential oil percentage, flower diameter, number of flowers and shoot weight were among the important and effective traits on essential oil yield. Slovakia, Izeh (2) and Poland had the highest fresh and dry shoot weight, flower diameter and essential oil yield, but Izeh (1) and Darrehshahr had the highest percentage of essential oil. According to the results of factor analysis, three factors were selected that explained 85.79% of the changes. The first factor, which justified the highest percentage of data changes, was named as the essential oil yield factor, which after drawing a biplot based on two components, Izeh (2) and Poland ecotypes were identified as superior ecotypes. Cluster analysis also classified the ecotypes into four groups, which performed well in differentiating the ecotypes based on the desired traits, and confirmed the distribution of the ecotypes based on the biplot diagram.

The results showed that the essential oil percentage, flower diameter, number of flowers and shoot weight were important and effective traits on essential oil yield. Due to the fact that diversity for these traits was observed among the studied ecotypes, so screening to increase these traits can increase yield. Slovakia, Izeh (2) and Poland had the highest fresh and dry shoot weight, flower diameter and essential oil yield, but Izeh (1) and Darrehshahr ecotypes had the highest percentage of essential oil.