Abstract
The Mediterranean basin is characterized by severe water scarcity. In some locations, such the north coast of Egypt, with very arid conditions, olive trees are the only option for growers, and can be grown only in irrigated lands. Water availability in these orchards is very limited, and severe deficit irrigation should be scheduled under conditions of high evaporative demand. The aim of this work was to establish the response of fruit set and fruit growth to deficit irrigation. Three deficit irrigation strategies were compared with growers' irrigation in a 10-year-old, 6.4x4.7 m 'Picual' orchard over two consecutive seasons. All treatments used the same amount of water over the season. One of the treatments adjusted the irrigation season in order to apply around 50% of crop evapotranspiration (ETc) over the whole season (T1). In the other treatments, irrigation was provided only during full bloom and fruit set (T2) or in this period and at the beginning of oil accumulation (only 2 weeks) (T3). Finally, growers irrigated over all the season with the amount of water available (T4). During 2009, fruit set was significantly higher in T2 and T3 than in T1 and T4. Fruit growth was also significantly reduced in T4, but not clearly in the rest of treatments. Yield pattern was similar to fruit set. In the 2010 season, there were no significant differences in fruit set or fruit growth. Yield was significantly reduced in T4 with respect to the rest. Influence of irrigation scheduling is discussed.