Assessment of the climatic condition’s impact on volatiles, polyphenols and mineral contents in tunisian olive tree (Olea europaea L.)

The severity of climate causes biochemical and nutritional changes in plants. Our study focuses on the adaptation of the olive tree to the climatic conditions by the improvement of essential oils, polyphenols and macro-elements synthesis in leaves, stems and roots of Meski, growing under various bioclimatic zones of Tunisia (North, Centre and South). The mineral content was determined using a flame photometer and the volatile components were analyzed by GC-FID and GC-MS. Meski cultivar resists to severe climatic conditions, in maintaining its nitrogen content almost constant in leaf and wood for all studied areas. Moreover, leaves showed richness in calcium and sodium than roots for all areas. The GC-MS analysis of Meski leaves allowed the identification of fifty seven components. The main constituents were (E)-β-damascenone, nepetalactone, geranic acid, (E)-β-damascone, (E)-nerolidol, (E)-2-decenal whose levels varied significantly with climate conditions. In fact, to adapt to the severity of climate, southern Meski leaves produced more essential oils and polyphenols than the northern ones. Therefore, the increase of essential oils and polyphenols can be considered as a response of the tree to surround aggressions and to oppose the oxidative stress that results from the severity of climatic conditions, characteristic of the southern area.