Phytochemical and physiological study of Satureja sahendica Bornm essential oil and extract to water-deficit stress

To investigate the effect of water-deficit stress on physiological characteristics, content and composition of Satureja sahendica Bornm essential oil, an experiment was conducted in greenhouse conditions in a randomized complete block with three replications in 2019. Different levels of water-deficit stress included: control at 100% field capacity, 40% and 70% field capacity depletion. Essential oils were extracted by water distillation and then were analyzed using GC-MS. After preparing methanolic extract, total phenol content was measured by Folin-Ciocalteu method. The results showed that water-deficit stress in both levels (40 and 70% moisture depletion) caused a significant reduction of 74.73 and 78.83% of dry weight compared to the control, respectively, but no significant difference was observed between the two stress levels. Water-deficit stress with 40 % and 70% moisture depletion led to a reduction of 18.49% and 30.87% of total chlorophyll content, 13.84% and 25.35% of relative leaf water content (RWC) content, respectively. The content of hydrogen peroxide, malondialdehyde and proline increased significantly under water-deficit stress conditions. The total phenol content increased by 25.78% and 48.44% in 40% and 70% moisture depletion, respectively. The most important composition of S.sahendica essential oil in all treatments included p-cymene, γ-terpinene and thymol; water stress affected the amount of these compounds and a significant increase of 11.47% and 30.65% in thymol content was observed in 40 and 70% moisture depletion, respectively. Based on the results, it was found that water-deficit stress can increase the physiological properties, quantity and quality of S. Sahandi essential oils.