Abstract

Thyme, one of the most important spices, is used all over the world, and includes many species. One of the most important commercially grown species is Thymus vulgaris L., which is endemic to the Mediterranean area. The objectives of this study were to determine the effects of foliar Cu2+, Mn2+, Fe2+ and Zn2* applications on shoot dry and fresh matter, root dry and fresh matter, height, number of stems per plant, essence percentage, carvacrol and thymol percentage in essential oil content of Thyme. Three treatments (0, 200 and 400 ppm) were used, and the experiment was repeated at two growth periods (2012 and 2013) in south-western Iran in a sandy clay soil. Cu2+, Mn2+, Fe2+ and Zn2+ applications affected plant height as the plants were shorter in the control treatment. Also, Cu2+, Mn2+, Fe2+ and Zn2+ applications increased the number of stems per plant, shoot dry and fresh matter, root dry and fresh matter, height, number of stems per plant and essence percentage. Applying 200 ppm of Cu2+, Mn2+, Fe2+ and Zn2+ made significant produced essence level in this investigation that was related to carvacrol production and the minimum one was related to thymol by a control treatment that was in similar group by concentration of 400 ppm of Cu2+, Mn2+, Fe2+ and Zn2+. Dry matter yield also increased about 100% with Cu2+, Mn2+, Fe2+ and Zn2+ during the 2-year study. In addition, Cu2+, Mn2+, Fe2+ and Zn2+ applications affected the essential oil yield. These results showed that applications of micronutrients could affect the growth and yield of Thyme, especially when the plant was grown in alkaline soils, and in this the 200 ppm concentrations of micronutrients were the best. Perhaps, the physiological basis of this effect was immobilization of micronutrients in this soil.