Effect of deficit irrigation on water use efficiency, yield and it's components of cotton ( Varamin cultivar)

The scarcity of water resources indicates optimum use of the water in the agricultural field. For optimizing water consumption of cotton, a field experiment conducted in Hadji Abad, located in the Hormozgan province. The experiments were conducted in a split plot design based on the Randomized Complete Block Design (RCBD) with three replications. The treatments were comprised of three levels of the crop water requirements (i.e. irrigation based on 100, 80 and 60 percent of crop water requirement) in main plot and with the two irrigation systems (surface and subsurface drip irrigation). The results showed in both systems, 60 and 80 percent caused parsimony of water usage, respectively equal to 3,200 and 1,500 m3 ha-1, in comparison with full irrigation. Water use efficiency in 80 percent treatment, increased 0.7 percent, in 60 percent treatment, decreased 3.8 percent in comparison with full irrigation. In plants treated with 60 and 80 percent of the irrigation water requirements, yield, respectively 37.2 and 15.6 percent, the number of bolls, 37 and 9.5 percent and boll weight 24.5 and 3 percent decrease. The yield, water use efficiency, number of bolls per plant and bolls weight in subsurface drip irrigation increased 12.1, 12.7, 27.2 and 17.5 percent, respectively, comparison to surface drip irrigation. Therefore, for cotton cultivation in Hadji Abad area, application of the subsurface drip irrigation system with 80 percent of water requirement pattern is the best way to increase the water use efficiency for the drought years.