Maize (Zea Mays L.) Response to Deficit Irrigation Levels at Different Growth Stages on its Yield and Water Use Efficiency at Koka, Central Rift Valley of Ethiopia

Water scarcity is among the major limitations for crop production. Improving water use efficiency of irrigated crops through water management options is crucial in water scarce areas. Field experiment was carried out at Wondo Genet Agricultural Research Center Koka Research site, to investigate the effect of water stress at different growth stage on yield and water use efficiency of maize. one optimum irrigation and eight growth stage based deficit levels(100% ETC at all growth stages, 75% ETC at all growth stages, 50% ETC at all growth stages, 75% ETC at development growth stage, 50% ETC at development growth stage, 75% ETC at mid growth stage, 50% ETC at mid growth stage, 75% ETC at late growth stage and 50% ETC at late growth stage) were imposed on maize (Zea mays L.) variety Melkassa II as a treatment and laid out in randomized complete block design (RCBD) with three replications. Results indicated that the different levels of growth stage based deficit levels had significant (p<0.01) effect on crop yield, harvest index and water use efficiency. Grain yield reduced with increased stress, whereas water use efficiency was increased with stress level increased. The highest grain yield of 6.4 t/ha and WUE of 1.01 kg/m3 were obtained at 100% ETC and 50% ETC at all growth stages, respectively. Also, 75% ETC at development stage and late stage treatments showed no significant variation with 100% ETC in grain yield. Water use efficiency observed at 75% ETC all growth stages treatment was statistically similar with that of 50% ETC at all growth stages treatment. Grain yield obtained from 50% ETC at mid growth stage was similar with 50% ETC at all growth stages, and water use efficiency was the least and this shows that maize was sensitive to moisture stress at mid growth stage than development and late growth stages. Therefore, maize could be irrigated at 75% ETC at all growth stages and by stressing development or late growth stages up to 50% ETC to increase water use efficiency with a small grain yield reduction for stressed scenario and for non stressed scenario with 100% ETC at all growth stages.