Irrigation with treated wastewater affected the minor components of virgin olive oil from cv. Chemlali in Tunisia

Water limitation for agriculture is a problem in many countries and irrigation with treated wastewater (TWW) can be a tool to face the decreasing availability of water for important domestic crops such as olive. Taking into account this aspect, a research was carried out for 13 years in an olive grove (Chemlali cultivar) located in the area of Sfax (Tunisia). Two different irrigation treatments were applied: (a) irrigation with good quality water (GQW) and (b) irrigation with TWW. The main objective of this 13-year study was to verify the effects of the irrigation with TWW vs. GQW on some minor parameters of the virgin olive oil. Many oil parameters significantly increased in the TWW irrigated plot, in particular lutein, total tocopherols, squalene, campesterol and stigmasterol whereas β-carotene, α-tocopherol, δ-tocopherol, β-sitosterol and total sterols decreased with respect to the GQW treatment. Irrigation with TWW can be a possible tool to irrigate olive groves with two positive effects: saving of freshwater and production of olive oil of good quality.