Effect of foliar boron applications on yield and quality of Medjool date palm

Effects of foliar boron (B) application as H3BO3 on yield and fruits quality of date palm (Phoenix dactylifera L. var. Medjool) were investigated. The experiment was conducted on 15 years old trees during 2017 growing season. Five different B levels (0, 400, 800, 1200 and 1600 ppm) were applied in a solution of 20 liters∙tree-1 at three equal doses in May, June and July. Fruit yield and quality parameters were determined at maturity harvest stage (tamer). The results showed that foliar B significantly affected yield, bunch weight, fruit set, fruit physicalcharacters and fruit quality. Boron application at the rate of 1600 ppm resulted in 27 % increase in fruits yield (67.7 vs. 53.4 kg∙tree-1), 16 % increase in fruit fresh weight and flesh weight (22.0 vs. 18.9 g.fruit-1), (20.9 vs. 18.0 g fruit-1), respectively, fruit size (49.97 vs. 45.3 mm) and fruit set (88 % vs. 81 %) compared to control. However, the lower rate of boron (400 ppm) was more effective in enhancing fruit quality indices. Total soluble solid (Brix % 75.0), fruit firmness (5.56 kg∙cm-2), glucose content (43.17 %), fructose content (39.28 %) and fruit antioxidant activity (80 %) were significantly increased as compared to control. On other hand, date syrup pH, fruit density and fruit skin separation were not affected by boron application. Overall, the results presented here recommended the use of foliar rates of boron ranging between 400 to 1600 ppm to enhance fruit yield and quality in Medjool dates.