Optimal Coupling Combinations between Irrigation and Seeding Rates for Improving Production and Water Use Efficiency of Wheat Grown under Arid Conditions

The sustainable use of water is becoming increasingly important for food security in arid and semi-arid
regions with limited water resources. This study was conducted to determine the optimal coupling combinations
between irrigation and seeding rates in order to achieve the high grain yield and efficient irrigation water use
simultaneously for wheat grown under arid conditions. The experiment was conducted during 2013/2014 and
2014/2015 growing seasons to study the effect of three irrigation rates i.e. 1.00, 0.75, and 0.50 of the estimated
evapotranspiration (ET) and five seeding rates i.e. 150, 250, 350, 450 and 550 seeds/m2 on yield components, grain
yield and irrigation water use efficiency (IWUE). The results indicated that grain yield and yield components of Sakha
94 were gradually decreased by decreasing irrigation rates and increasing seeding rates. The values of IWUE and
harvest index were decreased also by decreasing irrigation rate, while the highest values for both traits were achieved at
350 seeds/m2. The seeding rate of 350 and 250 seeds/m2 were most effective to obtain the lowest value for seasonal
yield response factors under 0.75 and 0.50 ET, respectively. Based on the production functions of grain yield versus
seeding rates for each irrigation rate, the optimum seeding rate for the maximum grain were 411 and 425 seeds/m2 for
1.00 ET, 362 and 378 seeds/m2 for 0.75 ET and 315 and 350 seeds/ m2 for 0.50 ET in the first and second season,
respectively.