Irrigation & Drainage Systems Engineering

Evaluating the Effects of Deficit Irrigation on Yield and Water Productivity of Furrow Irrigated Onion (Allium cepa L.) in Ambo, Western Ethiopia

Abstract

Temesgen T, Ayana M2 and Bedadi B

The objective of this study was, to evaluate the effects of deficit irrigation on yield and water productivity (WP) of onion crop grown under Ambo condition. Field experiment was conducted at Ambo Agricultural Research Center in Ethiopia. The treatments consisted of nine different treatments replicated three times arranged in RCBD. The experiment involved two categories of deficit with different timings: 1) skipping of irrigation during one particular phenological stage and application of 75% ETc during the rest of the growing stages and 2) no watering during specific phenological stage and watering with 50% ETc during the remaining stages. Amount of water applied was monitored using standard Parshall flume. The highest total onion yield (46.7t/ha) was obtained from full irrigated treatment, which was not statically different from treatments that were not irrigated during initial growth stage and irrigated with 75% ETc during the rest of phenological stages (T2) and treatment with no irrigation during bulb maturity stage and irrigated with 75% ETc otherwise (T5) (P<0.05). The second category of treatment (irrigation with 50% ETc) resulted high water saving and yield reduction which may not be attractive for producers. WP varied from 7.7 kg/m3 for control and 14.9 kg/m3 for the 50% stressed and not irrigated during maturity stage. T2 and T5 produced WP values of 10.8 and 13.1 kg/m3 respectively. From resources conservation point of view, maximum water productivity may be of interest, which could be obtained under sever deficit irrigation. However, such consequences on yield may not be tolerable from producers view point. The recommended depth of irrigation would be 75% ETc during development, bulb formation, maturity stages and skipping during initial growth stage. Skipping irrigation during maturity stages and irrigating with 75% ETc otherwise has more water saving and WP enhancement potential with tolerable level of yield reduction.