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 semiarid
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 (I100 D 5,370 and I75 D 4,027 m3 ha¡1). Irrigation of wheat by
I100 increased growth and uptake of nitrogen, phosphorus, and potassium
compared to low irrigation level. I100 caused 14 and 5% increase in straw and
biological yield, respectively, compared to I75. Grain yield and water use
efficiency (WUE) were higher by 20 and 59% in the case of I75 compared to
I100. 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 m3
ha¡1 is the optimum irrigation rate for maximum WUE and grain yield.