Effect of Harvesting Time on Content and Chemical Composition of Essential Oil from Stachys lavandulifolia Vahl (Lamiaceae)

Stachys L. one of the biggest genus of the Lamiaceae family comprises about 200-300 species.  In this research, aerial parts essential oil composition and content of Stachys lavandulifolia Vahl (Lamiaceae)at different stages (vegetative, full flowering and initial fruiting stages) is reported. The oils obtained by water distillation method (Clevenger apparatus) and analyzed by GC and GC/MS. The results showed that the essential oils of S. lavandulifolia were affected by plant growth stages. The chemical composition varied in three harvesting times. It was found that the maximum obtained essential oil was in the flowering stage. Totally, 31 constituents with the range of 0.10 – 34.11% in the vegetative, 27 constituents with the range of 0.06 – 36.35% in the flowering stage and 27 compounds with the range of 0.06 – 37.2% in the initial fruiting stages were identified. The highest compounds were related to the vegetative stage (34 compounds) that representing 63.74% of oil.  In this study, the highest amount of essential oil constituents in the vegetative stage belonged to germacren D (34.11%), n-decane (3.84%) and caryophyllene oxide (2.62%), in the flowering stage, germacren D (36.87%), borneol (4.3%), cis-thujone (4.24%), bicyclogermacrene (4.16%) & n-decane (3.88%) and in the stage of initial fruiting, germacren D (37.2%), borneol (4.76%), b-caryophyllene (4.20%), cis-thujone (4.16%) & bicyclogermacrene (3.99%).