THE RECENT investigation was conducted in two successive seasons.2012 & 2013 in commercial citrus orchard of 5-year-old Valencia orange (Citrus sinensis L. Osbek). Trees grafted on Volkamer lemon (Citrus Volkameriana) rootstock planted on 6 x 4m apart and located in Kafr Daoad, Behiragov., Egypt. The objective was to study the effect of spraying trees, three times; during winter time (mid of January) , full bloom and after two weeks with eight treatments of low biuret urea (LBU 1%), amino acids (AA 1%), calcium-boron (Ca-B 1.5%) and their combinations on the formation of inflorescences leaves, tree canopy volume, fruit set%, some fruit physical characteristics and the final yield. The combination of (LBU1%+Ca-B1.5%+AA1%) showed the best results with all the studied parameters in particular leafy inflorescence density and final yield.