عنوان مقاله [English]
Introduction: Thyme is an important medicinal plant in cosmetic, pharmaceutical and food industries. The genus Thymus L. (Lamiaceae) consists of about 300 species of herbaceous perennials and subshrubs. This genus is mainly distributed over Mediterranean country, northern part of Africa and Southern Greenland. Thymus species are commonly used as spices, herbal tea, insecticide and flavoring materials. Also, Thymus have been most frequently used in traditional herbal medicine due to its antiseptic, carminative, expectorant, antispasmodic, anti-inflammatory properties. Recent studies have showed that this genus have strong antifungal, antibacterial and antioxidant activities. Because of these medical features of this genus, Thymus is cultivated all over the world. The aromatic and medicinal properties of the genus thymus have made it one of the most popular plantsthroughout all of the world.
Materials and Methods: In order to study genetic variations, 22 populations of endemic species of Thymus include thirteen populations from species of T. daenensis, four populations of T. migricus and one population from each of the following species: T. fedtschenkoi, T. vulgaris, T. transcaspicus, T. pubsence and T. kotschyanus were used for assessment of morphology and essence value. Populations in completely random block design with three replications at the Razavi-khorasan Agriculture and Natural Resources Research Center were planted. Morphological measurement was taken on five random individuals of each replicate and average traits were analyzed. Clevenger unit was used to measure the essence amount. Morphological traits were included leaf length, leaf width, leaf number of year stem, maximum diameter of canopy, minimum diameter of canopy, canopy area, height flowering stem, height inflorescence, number of stems per plant, number days to starting of flowering, number days to 50% of flowering, fresh yield, dry yield, height of stem than inflorescence, and essence weight and volume. A balanced completely randomized design with three replications was used. Biometric measurement was applied to study the selected thyme populations. SAS, SPSS and NTSYS softwares were used for calculating the statistics indicators, normality tests, analysis of variance, means of traits, correlation coefficients, stepwise regression analysis and principal component analysis.
Result Discussion: A wide range of morphological variety was observed by biometric measurements. The results showed that there were highly significant differences between thyme populations. Mean comparison was carried out using Duncan method at 5% level. Population No.18 and population No.4 were showed the highest and the lowest diameter of canopy, respectively. Population No.18 and population No.4 exhibited maximum and minimum canopy area, respectively. Maximum and minimum stem lengths were related to populations No.12 and No.4, respectively. Maximum and minimum numbers of stems at each plant were seen in populations No.12 and No.2, respectively. Inflorescence length of population No.6 was maximum and population No.5 was minimum. The maximum and minimum average of the number of leaf per stem were observed in population No.17 and population No.12, respectively. Maximum and minimum of the leaf length were seen in populations No.10 and No.16, respectively. Population No.4 and population No.22 exhibited the highest and the lowest leaf width, respectively. For inflorescence length/ stem length ratio, population No.6 and population No.21 were showed maximum and minimum, respectively. The maximum number days to stating of flowering and 50% flowering, were seen in populations No.2 and No.8 and populations No.6 and No.4 had minimum of these. Population No.13 and population No.4 exhibited maximum and minimum dry weight, respectively. Populations No.13, No.17, No.18 and No.20 had the maximum of fresh yield and population No.4 had the minimum of fresh yield. For essence value characteristics, the most volume and weight of essential oil was observed in populations No.2, No.9, No.10 and No.18 and the least volume and weight of essential oil was observed in populations No.4, No.5, No.6 and No.12.
Conclusion: ANOVA showed that there was significant difference between thyme accessions for morphological traits which it is important for plant breeding. High variation increases selection of desirable traits for breeding. In order to crossing and hybridization, parents must be genetically distant to gain the most variation. In this study, relationship between thyme accessions using morphological and essence value traits was investigated so plant breeder can use it for production desirable hybrid.