Investigation of the effect of essential oils of Shirazi Thyme (Zataria multiflora) and Rosemary (Rosmarinus officinalis) on the invasive plant Centaurea balsamita

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.