To evaluate the effect of water stress at different crop growth stages on yield, yield components and water use efficiency, a field experiment was carried out in 2015/2016, 2016/2017 and 2017/2018 for bread wheat (Gambo variety) at Werer Agricultural Research Center. The experiment was laid out in Randomized Complete Block Design (RCBD) with three replications having 15 experimental treatments. Combination of water stress with crop growth stages was applied in the major investigation of the experiment. The highest grain yield was obtained from the control treatment irrigation at all stages (no stress). Stressing irrigation water at initial stages and maturity stages gave second highest yield (29.23 and 28.57 qt/ha) and lower water use efficiency (0.43 and 0.35 kg/m 3) respectively. While irrigating only at the initial stage gave highest water use efficiency (0.79 kg/m 3) and lowest grain yield. Application of irrigation water at all stages except initial and maturity gives optimum grain yield (26.73 qt/ha) and water use efficiency (0.62 kg/m 3) for the study area. Therefore, wheat should not be stressed at development and mid stage to obtain optimum water use efficiency (WUE) without a significant grain yield reduction.

Awash River is the main irrigation water source for mechanized farms and small land farmers established in the Basin for the last few decades. Recently, with the rise of Beseka Lake, the amount of discharging rate into the Awash has been a serious concern to Agricultural Production in the Middle and Lower Awash Areas. This study was conducted to evaluate the effects of Beseka Lake on irrigation water quality, soil physical-chemicals properties and Cotton yield. Seven levels of Awash River and Beseka Lake blended water (8, 10, 15, 20, 25, 30 and 50% of Beseka water) and a control (0% of Beseka water) as a treatment were arranged in randomized complete blocks design with three replications. Yield of cotton showed significant (p<0.05) difference among irrigation treatments and maximum yield of 41.393 q/ha was obtained from the control treatment and significantly differed from all other treatments. Blended irrigation water had impact on soil properties which decreased yield with increasing blending ratio. Soil properties, such as electrical conductivity (EC) (1.18), exchangeable sodium percentage (ESP) (12.95), as well as pH (8.66), increased due to blending effect of Beseka water. Blended irrigation water treatment ratio of 8% gave the highest yield (39.143 q/ha) and reduced yield by 5% as compared to the control treatment (41.39q/ha).