EFFECT OF DEFICIT IRRIGATION AND POTASSIUM FERTILIZER ON WATER CONSUMPTION AND CROP COEFFICIENT OF SORGHUM

Two field experiments were conducted during spring seasons of 2012 and 2013 at fields of State Board of Agric., in Abu- Ghraib, to study the effect of deficit irrigation and levels of potassium fertilizer during different growth stages on water consumption, crop coefficient and water use efficiency of sorghum (Sorghum bicolor L. Moench). A split plot in randomized complete block design was used with three replications. The four irrigation treatments: full irrigation (T1) and three deficit irrigation treatments, holding irrigation on non-consecutive irrigations during different growth stages (T2, T3 and T4) were allocated to the main plot. Whereas, the subplot were received the application of potassium fertilizer (0, 50, 100 and 150) Kg K.ha(-1) as potassium sulfate. The equation of the budget water was used to calculate ETc in term of moisture content before and after each irrigation at the depths of (30, 40 and 50) cm, according to the stages of growth. Pan A evaporation basin was used for calculation of ETo. The amount of seasonal water consumptive use for the treatment of full irrigation 573.9 and 576.8 mm for two seasons consecutively, and an increase of 5.30, 10.66 and 18.66% and 11.5, 15.29 and 19.34% for T2, T3 and T4 for two seasons consecutively, and that the average daily consumptive use for the treatment of full irrigation was 7.29 and 7.51 mm.day(-1) for two seasons consecutively, and for deficit irrigation ranged between 3.31-7.51 and 3.25-7.51 mm.day(-1) for two seasons consecutively. The T2 treat was the highest in water use efficiency 0.782 and 0.733 Kg.m(-3) of water, and 150 kg K.ha(-1) was the highest in water use efficiency 0.806 and 0.791 Kg.m(-3) of water for both seasons, repectively.