Essential oil yield stability of 20 populations of thyme (Thymus kotschyanus) across 11 environments of Iran

Abstract

Thyme is an important medicinal plant of Iran that in order to have Thymol and Carvacrol using as antimicrobial and antibacterial agent. The present study was carried out to determine the oil yield performances of 20 Thyme (Thymus kotschyanus) genotypes across eleven environments of Iran over 2 years (2013 and 2014). The experimental layout was randomized complete block design. Stability parameters were estimated as EberhartRussel stability, Lin-bin cultivar superiority, Ecovalence Wricke and Shukla stability variance analysis methods. Significant differences were observed for genotypes, Environment, and genotype × environment interaction (GE). According to Eberhart and Russel method, the high yielding genotypes 5, 56 and 70 had general stability with regression line (b =1), and thus considered adapted to all of environments. The results of Lin and Binns cultivar superiority (Pi) showed that, the genotypes of 5, 54, 56 and 50 with the lowest (Pi) values couple with higher oil yield were considered the most stable. Ecovalence (Wi) proposed by Wricke, showed that genotypes of 5, 56, 54 and 70 had lower Wi values couple with higher oil yield were considered more stable. The same genotypes in terms of Shukla stability variance also were introduced. In comparison between stability statistics, the genotypes stabilities in various methods were more and less similar. The genotypes of G5 (Ghazvin 2), G56 (Zarand) and G70 (Oromiea2) with average values of 1.66 to 1.70 Kg h-1 had higher general salability over all of environments. The genotypes G54 (Nagade) and G58 (Sanandaj2) with average values of 1.685 and 1.499 Kg h -1 had specific stability for poor environments. The genotypes G22 (Ghazvin3) and G50 (Zanjan4) with average values of 1.78 and 1.74 respectively had specific stability for rich environments.