EFFECT OF DEFICIT IRRIGATION ON WATER PRODUCTIVITY AND YIELD OF COMMON BEAN (PHASEOLUS VULGARIS L.) AT MELKASSA, CENTERAL RIFT VALLEY, ETHIOPIA

Abstract

The experiment was conducted at Melkassa Agricultural Research Center during off season under semi-arid climatic condition where moisture stress is higher. The study was under taken to evaluate effect of deficit irrigation on water productivity and yield of common bean (Phaseolus vulgaris L.).The experiment was split plot design with three common bean varieties as main plots and four deficit irrigation levels as sub plots all of which replicated three times. Four deficit irrigation levels 100%ETc, 85%ETc, 70%ETc, 55%ETc and three varieties SER-119, Bio fortified small seed-5, Awash-2 were used for treatment combination. The combined result indicates that there was a significant variation among treatments for yield, above ground biomass and water productivity. All common bean varieties were significantly affected under deficit irrigation levels. Consequently, highest yield (3.4 ton/ha) was obtained from irrigating 100%ETc followed by (3.2 ton/ha) with 85%ETc less yield reduction. In contrast the intermediate (2.8 ton/ha) and smallest yield (2.4 ton/ha) was obtained from irrigating 70ETc and 55%ETc.Water productivity was ranged from (0.83 kg/m3 ) at full irrigation to (1.33 kg/m3 ) at higher deficit irrigation. Based on obtained yield and water productivity, under a limited water supply situation where the goal was to gain highest possible yield of common bean and water productivity utilizing application of water from 70%ETC to 85%ETC at each irrigation event offers opportunities for water saving with yield reduction which was compensated by irrigating other area by saved water. The result of economic analysis shown that the highest net benefit obtained from irrigating full 100%ETc of the three common bean varieties. Based on obtained data the MRR was greater than 50% irrigating common bean with deficit irrigation 85%, 70% and 55% is economically feasible depending on accessibility of water