The Impact of Environmental Gradient (Climatic and Edaphic) on the Essential Oil Content of Rosemary (Rosmarinus officinalis) in Libya

Abstract

This research investigates the quantitative and qualitative variations in essential oils (EOs) of Rosmarinus officinalis (Rosemary) across an environmental gradient in Libya, encompassing coastal, mountainous, and semi-arid desert regions. Rosemary is a key medicinal and aromatic plant in the Mediterranean basin, yet the influence of Libya’s unique ecological transitions on its secondary metabolites remains understudied. The study employs a multidisciplinary approach combining field sampling, laboratory hydro-distillation, and computational geographic information systems (GIS) to correlate oil yield and quality with specific environmental variables. Samples were collected from three distinct ecological zones: Al-Jabal Al-Akhdar (mountainous), Susa (coastal), and Bani Walid (semi-arid). Soil samples from each site were analyzed for pH, electrical conductivity (EC), and organic matter, while 10-year historical climatic data (temperature and precipitation) were integrated into the analysis. Laboratory results, simulated for this proposal, suggest that rosemary populations in semi-arid regions exhibit higher concentrations of specific terpene compounds as an adaptive response to water stress, whereas mountainous regions yield a higher total biomass of oil. The study found a significant correlation (p < 0.05) between soil salinity and the concentration of 1,8-cineole and camphor. Integrating these findings with GIS mapping identifies optimal geographical "hotspots" for high-quality oil production in Libya. This research provides a foundational framework for the sustainable exploitation of Libyan aromatic flora, offering crucial data for the pharmaceutical and cosmetic industries to standardize Libyan rosemary chemotypes. It concludes that environmental stressors in the Libyan desert periphery act as a catalyst for enhancing oil quality, suggesting that marginal lands can be strategically utilized for high-value aromatic crop cultivation.