Herb yield and chemical composition of common oregano (Origanum vulgare L.) essential oil according to the plant’s developmental stage

The studies conducted in 2007–2008 were aimed to assess how the developmental stage of common oregano affected the quality and quantity of the herb yield. The field experiment was established with the use of random blocks in four repetitions. Oregano was grown from seeding produced in a greenhouse. Herbage harvest of one-year-old plants was conducted before flowering, in budding phase, at the beginning of flowering and in the full flowering phase. The yield of fresh and air dry herb yield and then the contents of essential oil was determined. The oil was chemically analyzed with the use of GC/MS method. It was demonstrated that the best term for oregano raw material harvest was the full flowering stage of the plants. In this period the yields of fresh and air dry weights as well as the essential oil contents were the greatest. The oil from the herb collected in the initial phase of flowering had the largest number of components, whereas the oil obtained in the budding phase had the smallest. The predominant components of oregano oil were: sabinene, germacrene D, E-caryophyllene, (Z)-β-ocimene and γ-terpinene. The examined oil also contained phenol compounds: thymol and carvacrol – highly bactericidal and fungicidal substances.