The effect of different irrigation levels on the Navel orange fruit quantity and quality was studied in the Jordan Valley through the 2007 and 2008 production seasons. Irrigation treatment consisted of control irrigation at 100% of crop evapotransperation and two deficit irrigation treatments. The latter irrigation treatments consisted of treatment at 75% of control irrigation, and at 50% of control irrigation. Fruits were harvested at five different periods, starting at the beginning of November in both seasons; harvesting took place at two-week intervals. The yield in both seasons of treatment at 75% of control irrigation was not affected significantly (p>0.05) compared with control. Yield of treatment at 75% of control irrigation was 36.1 t ha -1 and 26.17 t ha -1 in 2007 and 2008, respectively. As for control treatment, it was 35.17 and 28.15 t ha -1 for the same seasons. The yield of treatment at 50% of control irrigation was 29.16 t ha -1 for 2007 and 20.43 t ha -1 for 2008, indicating significant reduction (p?0.05). Total soluble solids, titratable acidity, and their ratio increased when reducing water irrigation. At the same time, juice percent and vitamin C were not nearly significantly different. Yield increased as harvesting progressed up to the third harvesting period (beginning of December) and started to decline by mid December. Fruits harvested at different periods showed a slight increase of juice percentage. Total soluble solids, total soluble solids/titratable acidity, and pH value increased significantly. A decrease of titratable acidity and vitamin C occurred as harvesting approached the third period. The results showed identical trends in both production seasons. From these results, two main conclusions can be obtained. First, the implementation of the 75% deficit irrigation instead of full irrigation would be recommended to save water while sustaining the same quantity and quality of yield. Second, the third harvesting period (beginning of December) is the more profitable harvesting period for Navel oranges at the different irrigation levels.
