effect of harvesting time on essential oil content and composition of thymbra spicata

this study aims to investigate the essential oils content of thymbr spicata l. in two times before flowering and full flowering in shirpenah area in ilam province. both samples were dried out in shade and without humidity. then 50 grams of each sample were powdered after obtaining the essential oils by hydro distillation using a clevenger apparatus for 2 hours. resulted oils were dried by anhydrous sodium sulfate and kept in tightly closed vials at 4 °c before chemical analyses. finally both essential oil samples were analyzed by gc and gc/ms. outcomes show that essential oils content in full flowering was (%4.04) more than before flowering (%3.64). the compositions of essential oils in before flowering were 7 compounds and major constituents were γ-terpinene (15.5%) and carvacrol (79.3%). the composition of essential oils in full flowering were 11 and the major composition also were carvacrol (70.5%) and γ-terpinene (14.9%). α-pinene, β-pinene, α-phellandrene and cis-sabinene hydrate were not found in compositions of before flowering. it is figured that flowering time is the best for obtaining the higher essential oils content and composition in t. spicata.