Effect of Foliar Applications of Urea on Flowering, Fruit set, Yield and Fruit Quality of Washington Navel Orange Trees

THIS STUDY was carried-out during two successive seasons …. 2014 and 2015 on 10 –year-old Washington Navel orange trees, cultivated in heavy loamy soil under El-Kalubia governorate conditions. Urea foliar applications at 1% or 2% concentrations in one time or twice at both mid of December and January. Morphological and microscopic studies cleared that, both Urea 1% one-time or twice applications improved the floral initiation and differentiation and reduced blooming process  period for Washington Navel orange from 8 to 6 weeks and increased the deformity pollen grains when compared to control. Urea 1% twice applications significantly improved fruit set and total yield and the most of physical and chemical fruit properties in this study . Moreover, urea 1% twice applications significantly increased total indols and reduced total phenols in flower buds during blooming stages which positively reflected on fruit setting and yield.