Abstract:
Crop production in Ethiopia is limited due to water scarcity. Various technologies and
management options are being used for efficient use of the available water resources in crop
production. Therefore, this study investigate the effect of stage-based deficit irrigation on the
performance of onion yield, water productivity, and identifies drought-sensitive crop growth
stages. The field experiment was conducted at Arba Minch university's demonstration farm
using furrow irrigation system with evapotranspiration-based irrigation scheduling.
Combinations of three deficit irrigation levels (75%, 50%, and 25% of the crop water
requirement) and three crop growth stages (development , mid-and late growth stages) were
used as treatment. Optimum irrigation of 100%ETc application was included as a control
treatment and irrigation water was applied at 25% depletion level of total available soil
moisture holding in crop root zone. The experiment was laid out in a randomized complete
block design with three replications. The result showed that deficit irrigation had a
significant (p<0.05) impact on yield. Maximum crop yield of 25.88 t/ha was obtained from
optimum irrigation water application. It was not significantly different from the yield
obtained in applying 75% crop water requirement at the late crop growth stage. Highest
crop water use efficiency of 6.83 kg/m3 was obtained in appliying 50% crop water
requirment at late growth stage.. Onion bulb yield was most sensitive to water deficit thatoccurred at bulb formation stage
