Onion yield response to irrigation level during low and high sensitive growth stages and bulb quality under semi- arid climate conditions of Western Ethiopia

Under the scarcity of irrigation water, the need to use the available water economically and efficiently is unquestionable. Deficit irrigation improves water use efficiency, by maintaining soil moisture content below optimum level throughout the growing season. The objective of this study was to study the effect of onion yield response to irrigation level during low and high sensitive growth stages and bulb quality under semi-arid climate conditions. The treatments consisted of 10 different levels of irrigation water application. The experiments were laid out in RCBD with three replications. The result showed that the variation in the level of irrigation water application had a significant effect on onion yield. Treatments that had deficit irrigation and skipping of irrigation in one growth stage had a lower yield than those that had full irrigation (P < 0.05). The highest total onion yield was observed from a control treatment (full irrigation), which was not statically different from the treatment receiving 75% ETc and no irrigation at the initial and late-season stage. Deficit by 75% ETc throughout the growing season resulted in the highest yield reduction. The crop water use efficiency was the lowest under full irrigation and the highest under 75% deficit throughout the growing stages. From resource conservation point of view, maximum water use efficiency may be of interest, which could be obtained under severe deficit irrigation. Therefore, there is a need to find out the deficit level at which a reasonable level of water saving can be achieved without significant yield loss, which could be of significant importance for both production and water conservation.