Development of Optimum Irrigation Regime for Onion Production at Arba Minch, Southern Ethiopia

This research was conducted aiming at development of optimum irrigation regime for onion (Allium cepa L.) production. A field experiment was conducted at Arba Minch area district, Southern Ethiopia during 2017 dry cropping season. The experimental treatments consisted four irrigation levels (100, 75, 50 and 25% ETc) and three irrigation intervals (3, 5 and 7 days). The experiment was laid out according to randomized complete block design in factorial arrangement with three replications. Results of the analysis revealed that the interaction effects of irrigation levels and irrigation intervals showed highly (P<0.01) significant difference on number of l eaves per plant and significant (P<0.05) difference on plant height, neck diameter and total bulb yield. The highest total bulb yield 34000 kgha-1 was obtained under control treatment which was statistically non significantly different with treatment combination of 100% ETc and 5 days interval. This study shows that shorter interval with higher level of irrigation had the better performance on all studied parameters, while the most stressed had low performance on all studied parameters. Therefore, application of 100% ETc at 5 days interval was economically productive when adopted by onion farmers in the study area when water was non limiting factor. However, 75% ET at 5 days interval can be an option in the study area when water was limiting factor. Keywords: irrigation regime, onion, Arba Minc