Effect of deficit irrigation on drip-irrigated wheat grown in semi-arid conditions of Upper Egypt

Shortage of water in arid and semi-arid regions increases the need of applying efficient drip irrigation system. A two-year field study in the semi-arid region of Upper Egypt was carried in randomized complete block design with four replicates. Wheat plants were irrigated by 100 or 75% of water requirements (I-100 = 5,370 and I-75 = 4,027 m(3) ha(-1)). Irrigation of wheat by I-100 increased growth and uptake of nitrogen, phosphorus, and potassium compared to low irrigation level. I-100 caused 14 and 5% increase in straw and biological yield, respectively, compared to I-75. Grain yield and water use efficiency (WUE) were higher by 20 and 59% in the case of I-75 compared to I-100. The use of deficit irrigation in drip-irrigated wheat under arid conditions is an effective tool to maximize efficiency of water use; moreover, 4,027 m(3) ha(-1) is the optimum irrigation rate for maximum WUE and grain yield.