Photosynthetic, anatomical and biochemical responses of olive tree (Olea europaea) cultivars under water stress

The effect of water deficit on photochemical parameters, hydraulic properties, phytochemical composition and radical scavenging activity were studied on fourOlea europaeacultivars (Chetoui, Oueslati, Jarboui and Meski). After 60 days without irrigation, maximum quantum yield of photosystem II (Fv/Fm), linear electron transport rate (ETR) and quantum efficiency of PSII electron transport (phi PSII) decreased in all cultivars. A significant decrease was observed for Jarboui and even more for Meski cultivars, reaching 0.57 and 0.24 for Fv/Fm, 1.41 and 0.65 for ETR, 0.51 and 0.23 for phi P-SII, respectively, Furthermore, water stress induced an increase in xylem vessel frequency, providing a greater security of xylem sap conduction under drought conditions. Chetoui had the highest total phenolic (37.4 mg GAE/g extract) and flavonoid (13.25 mg QE/g extract) contents under water stress. It had also the best antiradical activity by both DPPH and ABTS methods with antiradical activity of respectively 80.05% and 81.99%. Chetoui cultivar can be considered as the most tolerant one and we consider this cultivar very promising for cultivation in semi-arid areas.