EFFECTS OF HARVESTING HOUR ON ESSENTIAL OIL CONTENT AND COMPOSITION OF THYMUS VULGARIS

Diurnal variations in both fresh and dry leaf essential oils of Thymus vulgaris were evaluated in this study. Thymus vulgaris was harvested hourly starting at 6:00 and ending at 17:00. Fresh and dry leaf essential oil were extracted by hydrodistillation for 3 hours and analyzed by GC-MS. The results indicated that essential oil content significantly changed according to the hour of the day. The maximum oil yield was obtained by harvesting at the early hours of the day, which was found superior to oil yield corresponding to the late hours of the day. Thymol, gamma-terpinen, p-cymene and carvacrol were the dominant essential oil components of both fresh and dry leaves of T. vulgaris. Except thymol, slight variations in essential oil composition of fresh and dry leaf of T. vulgaris were detected among harvesting hours. The results showed that the best harvesting hours of T. vulgaris for higher thymol concentrations were between 6:00 and 11:00.