Monoterpenes

The experiment was conducted with the aim of investigating the characteristics of germination and growth of seeds and seedlings of starthistle under the influence of various concentrations of rosemary and Shirazi thyme essential oil. In the study of seedling growth characteristics, the factors considered were: A) Type of essential oil and B) Essential oil concentration (5, 10, and 20 µl/ml). The control treatments consisted of distilled water, distilled water + Tween 20, and herbicide. Rosemary at 0.5-20 µl/ml reduced plumule length by 32.33-100% and radicle length by 62.62-100%. Shirazi thyme at the same concentrations led to 83.67-100% reductions in plumule length and 83.49-100% reductions in radicle length. The reducing effect of Shirazi thyme essential oil on seedling shoot length and dry weight at concentrations of 20 and 10 µl/ml compared to rosemary was almost 2.2 and 2.7 times, respectively. Shirazi thyme exhibited a greater inhibitory effect on seedling root length and dry weight, compared to rosemary. Furthermore, with increasing concentrations of essential oil, particularly in the case of Shirazi thyme, electrolyte leakage increased and photosynthetic performance index decreased.

Essential oil from aerial parts of Tanacetum polycephalum Schultz Bip. subsp. polycephalum at the rates of 8000, 4000, 2000, 1000, 500, 250, 125, 62.5 and 0 mg l-1was tested for its nematicidal activity against the second stage juvenile (J2) of Meloidogyne incognita (Kofoid and White) Chitwood. 100 percent J2 mortality was achieved with essential oils of 8000 and 4000 mg l-1. Nematicidal activities were recorded as 44.4, 22.8 and 6 percentages for concentrations of 2000, 1000 and 500 mg l-1 respectively. No nematode mortality was seen in treatments of 250, 125, and 62.5 mg l-1of the oil. Analysis by Gas Chromatography (GC) and GC-Mass Spectrometry (GC-MS) led to identification of 39 major compounds from T. polycephalum oil. Among the chemical components, the main components were trans-Thujone (74.483%), 1,8-Cineole (3.135%), Terpinene-4-ol (2.316%), Borneol (2.351%), cis-Thujone (1.880%),Camphor (1.832%), trans-Pinocarveol (1.333%), and γ-Terpinene (1.059%).