Abstract

This study was conducted for three consecutive years to find an optimum irrigation regime, which allows the maximum yield of onion at Chano-Mille Kebele of Arbaminch Zuria Woreda. The experiment has four levels of irrigation treatments (125%MAD, 100%MAD, 75%MAD and Farmers practice or irrigating with own practice), laid down in Randomized Completed Block Design (RCBD) with four Replications. The highest marketable yield (24.219ton/ha) was obtained from 100% (MAD) where as the lowest marketable yield (17.292ton/ha) was obtained from 75% of MAD. From the result, the highest total yield (28.347 ton/ha) was observed from 100% (MAD), which was significantly different from other treatments. But, statistically, there was no significant differences in total yield among treatments of 125% of MAD (24.026ton/ha), 75% of MAD (20.555ton/ha), and Farmers' practice (20.703ton/ha). Moreover, the application of irrigation water above MAD and below MAD interval reduced total onion yield in the study area. The highest water use efficiency (5.4092kg m-3) was obtained from treatment of 100% (MAD) while the lowest water use efficiency (3.1029 kg m-3) was observed from Farmer practice. Therefore, the application of irrigation water at 100 %( MAD) was an appropriate irrigation amount and interval to obtain better marketable yield, total yield, and water use efficiency without adversely reducing onion yield in the study area.