445 Effect of Deficit Irrigation on Fruit and Oil Quality of ‘Konservolea’ Olives R. Rinaldi, M.L. Amodio and G. Colelli a Dipto. di Scienze delle Produzioni e dell’Innovazione nei Sistemi Agro-Alimentari Mediterranei Università di Foggia Via Napoli 25, 71122 Foggia Italy G.D. Nanos and E. Pliakoni Lab. of Pomology School of Agricultural Sciences Univ. of Thessaly Fitoko str, Volos 38446 Greece Keywords: Olea europaea L., water stress, yield, oil composition, chemicals Abstract The aim of this work was to evaluate the effects of deficit irrigation on quality of olives at harvest and on oil after processing. Olive trees (Olea europaea L. ‘Konservolea’) from Anchialos (central Greece) were subjected for 3 years (2006- 2008) to 2 different irrigation regimes: fully irrigated (Ctrl) and deficit irrigation (deficit). Control trees received 4000-5000 m 3 /ha of good quality water (conductivity <700 µS/cm) per year; deficit-irrigated trees were irrigated as control during the growing season except during stone hardening and final flesh swelling, when water supplied per day was 20% of the control. The 2008 data are presented. At harvest, fruit respiration rate, firmness, color score (maturity index), size and shape, water and oil content were determined. On oil samples extracted at harvest, the following quality attributes were measured: color, acidity, peroxide value, extinction coefficients at 232 and 270 nm, oil stability, total polyphenols, tocopherols, carotenoids and chlorophyll content, and fatty acid composition. Oil content was significantly higher in deficit treated fruit, while no other differences were observed on fruit quality. Yield was 9.6 t/ha, with no difference related to irrigation treatments. Reduced water supply led to some improvement in oil quality, as indicated by a lower acidity and higher stability, polyphenols and chlorophyll contents compared to the control. Besides, oil from deficit irrigation had similar oleic acid, higher palmitic acid, and lower palmitoleic, linoleic, linolenic and arachidic acids contents than normally irrigated samples. As a consequence, MUFA/PUFA ratio was significantly higher in oils obtained from deficit irrigated plants. No difference between treatments was observed for the sensorial attributes of extracted oil. INTRODUCTION Olives is a typical Mediterranean crop, traditionally cultivated in areas with little or no irrigation, although additional water supply tends to increase olive yield (Patumi et al., 1999). A good water supply is also very important for obtaining satisfactory fruit size of table olives, which is a factor strictly correlated to the commercial value of the product (Proietti and Antognozzi, 1996). Cultural practices are reported to affect quality and composition of olives and therefore extracted oil, although controversial data have been reported on the effect of irrigation on olive fruit ripening and fatty acid composition (Milella and Dettori, 1987; Wodner and Lavee, 1991). Early studies on the effect of irrigation focused on the acidic composition and showed that irrigation did not affect the fatty acid composition of the oil (Inglese et al., 1996; Patumi et al., 1999; Patumi et al., 2002). Berenguer et al. (2006) reported that mono-unsaturated fatty acid levels and oleic- linoleic ratios declined, while poly-unsaturated fatty acid levels increased with increasing irrigation. Among the olive fruit and oil chemical components, phenolic compounds are the most influenced by irrigation. Phenols affect both oxidative stability and sensorial charac- a g.colelli@unifg.it Proc. XXVIII th IHC – Olive Trends Symposium Eds.: J. Tous et al. Acta Hort. 924, ISHS 2011