Response of Onion to Deficit Irrigation Levels at Different Growth Stages on Yield and Water Productivity

The Ethiopian vegetable sub-sector, particularly onion, is crucial for the economy due to its high productivity and ease of cultivation. However, water scarcity in arid and semi-arid regions hinders its expansion. This study conducted at Wondo Genet Agricultural Research Center aimed to investigate the impact of deficit irrigation levels at various growth stages on onion yield and water productivity. The experiment employed a split plot design with four crop growing stages and three deficit irrigation levels. Results revealed that deficit irrigation significantly affected onion growth parameters and yield components. Bulb diameter, number of leaves per plant, and total bulb yield 5.84 cm, 6.85, 23.26 t/ha, respectively, were notably influenced by deficit irrigation levels, with the highest yields observed under full irrigation. Additionally, water use efficiency varied with deficit irrigation application timing, with the highest efficiency recorded during the maturation stage. Overall, deficit irrigation during initial and maturation stages at 55% ETc application level emerged as the most viable option, ensuring sustainable crop production in water-scarce areas. These findings underscore the importance of adopting deficit irrigation strategies to optimize water use efficiency and enhance onion yield in Ethiopia's vegetable sub-sector.