Studying behavior of navel orange trees under different irrigation treatments in the north middle nile delta.

This study was carried out to evaluate the effect of three irrigation treatments (irrigation when 25, 50 and 75% of available soil moisture was depleted) in comparison with farm control treatment (traditional irrigation like to practice by local farmers) in the studied area on some water relations, productivity and fruit quality of Washington Navel orange trees under clay soil conditions during two successive seasons 2013 and 2014 at a private orchard in Desok district, Kafr El-Sheikh Governorate. The results showed that, the highest amount of applied water (7838.4 and 7389.8 m³/fed.), water consumptive use (113. 8 and 109.1m³/fed.) and stored water values in the effective root zone (5591.4 and 5391.7 m³/fed) were recorded under control treatment compared to the lowest values obtained by irrigation treatment when 75% of available soil moisture was depleted in both seasons respectively. The highest values of water application efficiency (82.90%) and consumptive use efficiency (65.72%) were recorded under irrigation treatment 75% of available soil moisture was depleted compared to the lowest values 72.15 and 61.5% respectively, obtained by control treatment in both seasons. The highest values of Water productivity (7.51 and 7.52 kg/m³) and productivity of irrigation water (4.81 and 4.95 kg/m³) were recorded under irrigation treatment I₃ in the first and second growing seasons respectively.The trees were irrigated when 50% of available soil moisture was depleted gave the highest fruit yield and number of fruits per trees and tended to increase peel firmness, and thickness, SSC, acidity, Vit.C, and juice weight compared with the control. For N and K concentrations in leaves, results showed that irrigation treatments showed no significant effect on N and k but significant effect on P concentration.