Studies On Biological And Essential Oil Characteristics Of Thymus L. In Liaoning Province

Thyme is a group of ground cover plants with aroma that can be used as ornamental, edible and medicinal plant. The germplasm resources of Thymus L. is abundant in Liaoning province. Few system research carried out about the biological and essential oil characteristics of thyme in Liaoning province. A lot of resources were put to use in landscape engineering by transplanting from wild which broke the balance of the thyme community. The thyme distributed in Liaoning and all resources was collected. The germplasm nursery were build and used to observe the botanic and growth characteristics. The ornamental value and drought resistance of thyme were evaluated. Propagative technique and Characteristics of essetial oil were studied in some selecting outstanding thyme species. The result ensured the classification and distribution of thyme in Liaoning province. The evaluation and appraisal system were completed about the thyme in Liaoning province, which established the research basis for resources protection and variety breeding. The main results are as follows:1.The research have figured out the distribution of thymus in Liaoning Province, established Liaoning germplasm resources garden of thyme in the Baicao Garden of Shenyang Agricultural University. Th. mongolicus Ronn and Th.dahuricus Serg mainly distributed in the north of Liaoning Province, such as Jianping, Jianchang, Beipiao, Lingyuan, Beizhen, Yixian, Fuxin, Zhangwu etc. Th. quinquecostatus Celak.and Th. przewalskii Kom. distributed in the south of Liaoning Province, such as Dalian, Yingkou, and Haicheng. Th. disjunctus Klok. merely distributed in Dandong. Through the observation and comparison of the botanical characters of these 5 species of thyme, we found some trait was stable, such as plant height, flowering branch height, minor number, separation distance, pattern of earring out, insertion of hair, color of flowering branch, leaf shape, leaf vein, petiole, leaf margin, leaf hair, separation distance, corolla length, pedicel length, spots on petal, color of filament, rachis, hair on the pedicel, rapid pulse and color of calyx, shape and hair of labial tooth, early flowering phase, can be used as the basis for classification and identification of thyme.5 species of pollen grains of Liaoning Province thyme are long shere. Equatorial view oblong or elliptic, six-lobed circular in polar view,6 ditch. Pollen grains of Th. quinquecostatus Celak. are biggest, about 32.77μm×26.51μm, the minimum P/E value, closer to spherical; Pollen grains of Th. disjunctus Klok. are smallest, about 20.24μm×26.18μm, the P/E value of Th. mongolicus Ronn. is minimum, closer to spherical. From the growth stage and flowering habits, Th. disjunctus Klok. resume growth earlier, and has longest flowering period, including florescence of single flower, single plants,the whole flowering, and blooming stage. Th. dahuricus Serg. and Th. przewalskii Kom. have the longest green period.2. With the increase of drought stress, relative water content of 4 kinds of thyme leaves gradually decreased; MDA and relative conductivity values gradually increased, the activity of POD increased first and then decreased; free proline content and soluble sugar content showed increase-decrease-increase-decrease, like "M" trend. Based on 7 physiology and biochemistry indexes, comprehensively assessed the drought resistance of four species of thyme, the declining order is Th. vulgaris., Th. quinquecostatus Celak., Th. przewalskii Kom., Th. mongolicus Ronn.3. Th. quinquecostatus cutting propagation was sandy soil. The average rooting rate in sandy soil can reach 67.5%, the root number was 3.5 and the root length was 3.20 cm. The root length of Thymus quinquecostatus in sandy soil were 1.27 times and 2.04 times as much as them in soil for breeding seedling and rural soil respectively. Rooting agent had no effects on root number, root length and root weight. Rooting rate of cutting from the upper part of shoot was 73.3%, the root length and root weight were 2.99 cm and 0.0188 g respectively, which had significant difference with the lower part of shoot. The study demonstrated that it is best to cut the upper part of the shoot and slip into the sand, which would take root much more.4. The results of a two-way ANOVA showed that temperature, drought and their interaction significantly affected the Th. vulgaris. seed germination and seedling growth. Seed germination was optimal at the temperature range from 8℃ to 24℃ in the concentration of 0-10% PEC, and germination percentage was the highest at 10℃ to 12℃. It was significantly different from the other treatments. At the concentration of 15% PEG-6000, seed germination percentage was significantly inhibited, until the concentration of 30% PEG only a few seeds germinated at 22℃ to 24℃. After germination, at the temperature regime of 22℃ to 24℃ and in the concentration of 0-10% PEG, root length, and shoot length were significantly higher than the other treatments. Seeds and seedling growth were showed different response in PEG-simulated drought stress and low temperature.5. Different parts of thyme have different volatile oil content, the declining order is flower, leaf, whole grass, stem, and root. In 2 kinds of thyme, flower, leaf and whole plant essential oil content in cultivated Th. vulgaris.was significantly higher than that of Th. quinquecostatus Celak. Thyme in different growth stages, from pre flower to flower later, essential oil content first increased and then decreased trend, essential oil content of full flower is highest. Blooming stage is the most appropriate period to harvest the leaves and flowers for the extraction of volatile oil. Different kinds of thyme plant have different essential oil content and composition, thymol is an important component of volatile oil of thyme, the main chemical composition of Th. vulgaris.is thymol and the content is higher than Th. quinquecostatus Celak. The bases of Th. quinquecostatus Celak. are thymol and borneoL. The volatile oil content of thyme is closely related to carbon and nitrogen metabolism in plant. As analysis of different growth stages of volatile oil content and some physiological and biochemical indexes showed that, volatile oil content of thyme at growth period and soluble sugar, total nitrogen and protein nitrogen showed a significant negative correlation relationship, and total organic carbon and C/N was positive correlation.