Study on some environmental factors effects on Salvia multicaulis Vahl. essential oil composition in Hamadan province

The Salvia species are of great importance in food, pharmaceutical, and cosmetic industries for their secondary metabolites. Although the production of secondary metabolites is encoded by the plant genetic, however, environmental factors have a great influence on their production and composition in plants. In this study, to investigate the effects of some climatic factors, topography, and soil parameters on Salvia multicaulis essential oil composition, the plant samples were collected from nine different habitats in Hamadan province during the flowering season. The soil samples were also taken for each plant in the sampling sites. The essential oil was extracted by hydrodistillation (Clevenger apparatus) and its composition was identified by GC and GC/MS. The soil factors were measured according to the relevant protocols and the climatic records were collected from the meteorological stations of Hamadan province. The RDA analysis was used to investigate the effects of different environmental factors on the essential oil composition. Clustering of the studied habitats was performed based on the major compounds of essential oils using the Wards method. The essential oil composition was different in different habitats. The compounds α-pinene (1.3-32.1%), α-phellandrene (1.1-7%), 1,8-cineole (1-17.2%), bornyl acetate (7-16.2%), and β-caryophyllene (9.1-40.6%) were the major ones of this plant essential oil. The RDA results showed that the essential oil content and oxygenated terpenoids percentage increased with increasing altitude, but the hydrocarbon terpenes percentage had an inverse correlation with altitude. The monoterpenes had a positive correlation with the relative humidity, rainfall, and soil organic carbon, but the sesquiterpenes had an inverse relationship with these factors and showed a positive correlation with phosphorus and to some extent with calcium of the soil. The studied habitats clustered into two distinct groups with predominance of monoterpenes and sesquiterpenes in the essential oil. These findings could be important for commercial exploitation of sage with the aim of extracting specific secondary metabolites in its essential oil.