Influence of soil salinity on the chemical composition of essential oil of Rosmarinus officinalis in Syria

This work aimed to investigate salinity influence on the biosynthesis of essential oil and its constituents in Rosmarinus officinalis (rosemary), and to optimize yield by modulating environmental factors (soil). Four groups of Rosmarinus officinalis plants were cultivated, each containing four samples, over a four-month period from May to September (2011). The irrigation solutions utilized a salinity gradient ranging from 25mM to 100 mM, with each group being irrigated separately on average every three days. The fourth group irrigated with distilled water served as a control. Essential oils were extracted from both cultivated and wild groups, in both fresh and dried states. Eight samples were collected from various regions in Syria, including Salkhad, Swieda, Sheikh Badr, Tartous, Faculty of Agriculture at the University of Damascus (cultivated samples), and Kalamoon. The highest quantities of oil were extracted from samples in the Sweida and Kalamoon regions. Rosemary leave essential oil contains numerous chemical constituents in proportions depending on the plant's origin. The GC-MS data revealed an elevated concentration of oxygenated compounds, such as camphor, borneol, and verbenone, in the cultivated samples. Additionally, the results demonstrated that soil salinity within permissible limits could enhance production and improve the essential oil yield of the plant.