The Effect of Water Stress on Leaf Phenolic Composition, Fluorescence Parameters, Xylem Hydraulic Properties and Antiradical Activity of Four Tunisian Olive (Olea europaea L.) Cultivars

Chlorophyll content, fluorescence parameters, xylem hydraulic properties, total phenolic content and antiradical activity were studied on young plants of four Tunisian olive cultivars (Chetoui, Ouslati, Jarboui and Meski) grown under water deficit conditions for two months. Water stress caused a decline in chlorophyll content, in maximum quantum yield of photosystem II (Fv/Fm), in linear electron transport rate (ETR) and in quantum efficiency of PSII electron transport (Φ PSI). Chetoui variety was the less affected by water stress but all these parameters decreases considerably in Ouslati, Jarboui and Meski. In all cultivars, water stress induced an increase in xylem vessel frequency. Water stress also increased the phenolic and flavonoid contents and antiradical activity in all cultivars. Chetoui cultivar may be considered as the most tolerant cultivars among the tested cultivars showing higher phenolic and flavonoid contents and an important antiradical activity under water deficit. Meski cultivar is the most sensitive one.