Effect of Deficit Irrigation on Yield and Water Productivity of Onion (Allium cepa l.) under Conventional Furrow Irrigation System, in Bennatsemay Woreda, Southern Ethiopia

The field experiment was conducted in Bennatsemay Woreda, Enchete kebele during 2018 season with objective of investigating the effect of deficit irrigation on yield and water productivity of onion under conventional furrow irrigation system. Six treatments (T1=100% ETc, T2=85% ETc, T3=70% ETc, T4=50% ETc, T5=100% ETc Is, 85% ETc Ds, 70% ETc Ms, 50% ETc Ls and T6=85% ETc Is, 70% ETc Ds, 50% ETc Ms, 0% ETc Ls) were imposed on onion (Allium cepa L.) and laid out in randomized complete block design (RCBD) with four replications. Results indicated that the different deficit irrigation levels had highly significant (p < 0.01) effect on vegetative growth, yield, yield components and water use efficiency of onion. The highest bulb yield of 21.3 t/ha were obtained from T1 which was significantly different to all other treatments while yield from T6 (12.86 t/ha) was recorded as the lowest one. Similarly, the highest IWUE (2.41 kg/m3) and CWUE (4.02 kg/m3) were obtained from T6. However, at T4 and T6 high yield reduction was recorded which may not be attractive for producers. Therefore, it could be concluded that increased water saving and water productivity through irrigation at 70% ETc deficit irrigation level under conventional furrow irrigation system can solve the problem of water shortage and would ensure the opportunity of further irrigation development in the study area and similar agro-ecology.