Environmental stresses such as water scarcity induce particular secondary metabolite pathways. Plants produce different types of secondary metabolites to improve their performance upon exposure to biotic and abiotic stresses. Salvia officinalis is one the most common medicinal and aromatic plant species belonging Lamaiceae, native to the Mediterranean region, although it has been naturalized in many places throughout the world mainly because of its high medicinal value[1]. This study examined the effects of various drought stress levels, i.e. 20% (W1), 40% (W2), 60% (W3) and 80% (W4) water depletion of field capacity (FC) on essential oil constituents of S. Officinalis plant under greenhouse conditions. Essential oils were obtained by hydrodistillation method and analyzed using GC and GC/MS apparathus. Data were subjected to analysis of variance in a completely randomized design (CRD) with three replications. The results showed that essential oil of aerial parts of plant predominantly consisted of monoterpenes such as 1,8-cineol, cis-thujene, camphor, borneol and trans-thujon. The content of these compounds significantly varied among different employed treatments. The highest content of 1,8-cineol (34.2%) and cis-thujene (24.6%) were observed at W3 stress treatment. However, maximum value of camphor (28.4%) and borneol (24.8%) were achived under W2 condition. Furthermore, maximum (25.5%) and minimum (18.9%) content of trans-thujon were obtained at W3 and W1 drought stress subjected plants, respectively. The biosynthesis of monoterpenes occurs in glandular trichomes of the leaf surface [2]. It has been reported that the higher density of non-glandular and glandular trichomes under stress conditions could be related to water conservation and high amount of essential oil conetnts in medicinal plants [3].
