| چکیده انگلیسی مقاله |
Background and Objectives
Thymus L. species (Lamiaceae family) are among the most important medicinal and aromatic plants, showcasing significant morphological, genetic, and phytochemical diversity. Thymus lancifolius Celak is one of the endemic species of Thymus in Iran, valued for its high concentration of phenolic compounds, which contribute to its economic and medicinal significance. The objective of this study was to cultivate, evaluate, and identify high-yielding and stable genotypes in terms of aerial dry matter yield and essential oil yield using the GGE-biplot method.
Materials and Methods
In the evaluation of thyme germplasm in the national botanical garden at the Research Institute of Forest and Rangeland, Tehran, eleven genotypes of Th. Lancifolius was identified. The seeds of genotypes were sown in pots in a greenhouse. The seedlings were moved to the field in 13 research farms in the provinces of East Azerbaijan, Isfahan, Razavi Khorasan, Zanjan, Qom, Markazi, Hamadan, Golestan, Yazd, Semnan, Ardabil, and Tehran (Botanical Garden and Damavand-Hamand Absard). The seedlings were transplanted in the field under dripping irrigation as spaced plants with the arrangement of 75×75 cm (15 plants per plot) based on randomized complete block designs with three replications in April 2009. No data were recorded in the establishment year. In the second and third years, at the time of the 50% flowering stage, thyme plants were harvested and dried under shade conditions. The hydro-distillation method extracted the essential oil from the dried and powdered shoots using a Clevenger design apparatus for three hours. All collected data, including aerial dry matter yield, essential percentage, and oil yield, were subjected to analysis of variance. The mean of genotypes was compared with the control (Thymus vulgaris) using LSD (p<0.05). Since the result of the analysis of variance showed significant effects of genotype, environment, and genotype by environment interaction for all the traits. GGE biplot analysis was employed to evaluate the yield stability over 13 locations using R4.5 software.
Results
A high value aerial DM yield (1627 kg/h/year) was obtained in genotype 48, which had no significant difference with the control (Th vulgaris). Whereas, DM yields of the other genotypes were significantly lower than the control, and they were ranked in the second class. For essential oil percentage, the trend was different, and half of the genotypes had significantly higher essential oil percentages than the control. The highest essential oil percentage, with values of 1.71 and 1.62%, was obtained in genotypes 1 and 45, respectively, which were significantly higher than the control (1.04%). For essential oil yield, the average values of 22.8, 22.3, 24.1, and 23.9 kg/h were obtained in genotypes 1, 45, 48, and 61, respectively, which were significantly higher than the control (19.1 Kg/h). A stability analysis was made for functional traits using the average environment coordination (AEC) axis with an ideal genotype; the stable genotypes were recognized over all environments. For aerial DM yield, genotypes 45 and 48 and the control, for essential oil percentage, genotypes 1 and 45, and for essential oil yield, genotypes 1, 41, 45 and 48, were close to the AEC axis, and they were recognized as a stable genotype over all environments.
Conclusion
According to the results of the combined analysis of variance and stability using the GGE biplot method, three genotypes, 1 (Farahan), 45 (Freydonshahr), and 48 (Khoramabad), were selected as superior genotypes for evaluation in extension research projects and seed production due to their high DM yield, essential oil content and essential oil yield, and general stability of yield in multiple locations. |