Influence of Irrigation Scheduling on Fruit Quality of Young Potted 'Manzanilla de Sevilla' Olive Trees

The aim of this work was to analyse the influence of soil water content and distribution on fruit quality in 5-year-old 'Manzanilla de Sevilla' olive trees in pots subjected to different irrigation treatments for 3 years (2007-2009). The experiment was carried out near Seville, in southwest Spain. Four water treatments were considered: 1) T0, trees were under dry farming conditions except for small amounts of water supplied to ensure their survival; 2) T1, irrigation dose was about 50% of the crop's water needs (ETc); 3) T2, irrigated at 100% of ETc. Some of the roots of the T1 and T2 trees were left in drying soil during the irrigation season; 4) T3, irrigated to non-limiting soil water conditions in the whole rhizosphere throughout the irrigation season. All treatments were fertilized under non-limiting conditions. Results from the 2009 season showed no differences between treatments in either fruit or endocarp shapes. In all cases, the longitudinal diameters of both fruits and endocarps increased with the amount of water applied, as did equatorial diameters, except without significant differences between irrigation treatments. Fruit weight, volume and the mesocarp/endocarp ratio also increased with the amount of water applied. Those increments were mainly related to those of fresh and dry mesocarp weights. The endocarp weight, both fresh and dry, was lower in T0 than in the irrigation treatments, with no differences between irrigation treatments. Oil content on a fresh weight basis decreased significantly with the amount of irrigation and no differences between T2 and T3 were found. These results show both a positive response of fruit quality to regulated deficit irrigation and the fact that wetting the whole rhizosphere to around field capacity influences little, if any, the fruit quality.