what is impact of regulated deficit irrigation and foliar Zn nanoparticles application on
productivity of mango trees? the answer to this question represents the main objective of this study. To verify
this, an experiment was performed during the 2016/2017 on the mango trees mango (Mangifera indica L.) cvs."
Nawomy" and "Sokary" which have about 16 years old in sandy soil under drip irrigation system. 100, 50, 75%
of the crop evapotranspiration "ETc" were used, in parallel with three levels of concentrations of NPs-Zn
micronutrient (0, 50, and 100 ppm) were applied three times; i.e., before flowering, 10 days after full bloom and
after fruit set stages in both seasons. The highest yield and water-use efficiency were obtained with applying the
RDI-75% of ETc treatment without significant difference that 100% of ETc treatment. The average fruit weight
and size, length and width were larger for mango fruits from the 100% of ETc and 75% of ETc, with TSS%,
total reducing sugars and ascorbic acid content being significantly greater than fruits of other irrigation
treatments. Therefore, using the nano zinc as foliar sprays on mango trees at a concentration of 100 ppm
improved fruit set percentage, total yield fruit quality (physical and chemical properties), also increased water
use efficiency. It could be concluded that irrigated trees with 75% of ETc plus foliar spraying of nano zinc
(NPs-ZnSO4) at 100 ppm was the most effective treatment for increasing fruit set, total yield and quality as well
as water use efficiency of Nawomy and Sokary mango trees.