Stability analysis of essential oil yield in different populations of thyme (Thymus kotschyanus) in different regions of Iran using GGE biplot

To determine essential oil yield stability in different populations of thyme (Thymus kotschyanus), 20 plant populations were examined in normal conditions at 11 stations, consisted Damavand, Esfahan, Golestan, Hamedan, Khorasan, Markazi, Qom, Tabriz, Tehran, Yazd and Zanjan. Data were analyzed in split plot in location design. Based on combined analysis of variance, genotype × location interaction was significant at (p>1%). This showed differences of the studied populations in yield and response to different conditions in eleven locations. In Graphical analysis, 11 environments were divided into 3 Mega environments. In mega environments Khorasan, Qom, Markazi, Damavand, Yazd, Zanjan and Tehran, genotypes 5, 27, 51 and 54 showed special compatibility. Genotypes 3 and 17 in Tabriz and Hamadan mega environment and genotypes 10, 8, 70 and 50 in mega environment of Golestan showed special compatibility. Assessment based on essential oil yield and stability of genotypes showed that accessions 5, 54 and 29 were suitable accessions. Graphical analysis of relationships between the environments, Khorasan, Qom, Markazi and Damavand, formed a group environment. Khorasan, Tabriz, Isfahan and Golestan locations showed significant role in differentiation of the studied genotypes. Based on graphical analysis of relationship between the genotypes, genotypes of 54 (Naghade), 27 (unknown 1), 51 (Tehran), 56 (Zarand) and 5 (Qazvin 2) formed a high production group presenting special compatibility to mega environment of Khorasan, Qom, Markazi, Damavand, Yazd, Zanjan and Tehran. The mentioned genotypes could be used for thyme cultivation in the mentioned areas.