Yield and water use efficiency of deficit-irrigated maize in a semi-arid region of Ethiopia.

Scarcity of water is the most severe constraint for development of agriculture in arid and semi-arid areas. Under these conditions, the need to use the available water economically and efficiently is unquestionable. Based on the actual crop need, the irrigation management has to be improved so that the water supply to the crop can be reduced while still achieving high yield. The purpose of this study was to determine the water use efficiency of maize (Katumani cultivar) under deficit irrigation practice and to identify crop growth stages during which the crop can withstand water stress with limited effect on yield. The field experiment was conducted at the experimental farm of Haramaya University located in Dire Dawa, Ethiopia. The treatments consisted of ten different levels/timings of irrigation water application. Treatments T1 and T2 were respectively normal irrigation and 75% deficit irrigation throughout the growing season. T3, T4, T5, and T6 were stressed by 75% at a specific stage: initial stage, development stage, mid season stage, and late season stage respectively. T7, T8, T9, and T10 were stressed by 50% at the respective four growth stages. The result showed that variation in level (amount) of irrigation water application had a significant impact on grain yield. In the case of stress by 75% deficit at a specific stage, the effect of stress was severe during the mid season stage. The mid season stage was the most sensitive to water stress. On the other hand, water deficit during the early and maturity stage had a limited effect on yield. Stressing the crop by 75% deficit throughout the growing season resulted in the highest yield reduction. However, the crop water use efficiency was the lowest (1.72 kg/m3) at optimum irrigation water application and the highest (2.96 kg/m3) at stress of 75% deficit throughout the growth season. Although at individual farmer’s level, maximum yield is obtained when the entire crop water requirement is fulfilled, practicing deficit irrigation could increase the irrigated area as a result of high water use efficiency.