MEDITERRANEAN AROMATIC PLANTS AND ESSENTIAL OILS AS SUSTAINABLE SOLUTIONS FOR RESTORING AND VALORISING MARGINAL LANDS IN SARDINIA

Mediterranean marginal lands are increasingly affected by salinity and potentially toxic element (PTE) contamination, limiting their agricultural use and requiring sustainable recovery strategies. This PhD project evaluated Mediterranean aromatic plants and their essential oils (EOs) for the restoration and valorisation of marginal soils in Sardinia. Germination and early seedling development of six aromatic species were assessed in saline and mining-impacted substrates, revealing strongly species- and site-dependent responses. Phytotoxicity was more closely related to the labile PTE fraction than to total concentrations, while Salvia officinalis, Ocimum basilicum and Lavandula angustifolia showed the greatest early tolerance. Lavender EO was then tested as a foliar biostimulant and antimicrobial agent in radish and baby leaf lettuce. Low doses promoted growth, biomass, pigments and nutrient uptake, whereas higher doses induced neutral or inhibitory effects, confirming a hormetic, concentration-dependent response. Artemisia arborescens, naturally established in Sardinian mining areas, combined ecological tolerance, negligible PTE transfer to EOs and site-dependent biostimulant and antibacterial activity. Conversely, basil establishment in contaminated soils was severely constrained without amendment. Compost from urban organic waste improved survival, water status, photosynthetic performance, biomass and oxidative balance, while reducing PTE accumulation in a soil-, organ- and element-dependent manner. Essential oils obtained from plants grown on contaminated substrates remained below reference limits for PTEs, although their chemical composition varied with site and treatment. Overall, the findings support an integrated phytomanagement approach combining resilient aromatic species, compost amendment and EO production to stabilize contaminated soils, restore ecological functions and generate safe, high-value products within a circular and sustainable land-use model.