KASECH BELACHEW2026-02-182019-10-24https://etd.hu.edu.et/handle/123456789/940Availability of water in the required quality and quantity is vital for crop production. Water scarcity does not only occur in arid and semi-arid areas but also it occurs in areas that receive high rainfall and have abundant fresh water resources. Especially in regions with water shortage, deficit irrigation strategies have become important tools to attain higher water use efficiency and optimum yield. Proper irrigation interval is also used to utilize scarce water resources efficiently and effectively by applying the required amount of water when it is needed. These, however, need testing the application of the system under specific condition for a given crop. The objective of this study was to investigate the response of yield and above ground biomass of haricot bean (Phaseolus vulgaris L.) under deficit irrigation and various irrigation intervals in Adami Tullu, Oromia, Ethiopia. The treatments were comprised of factorial combinations of two factors. The treatments were four levels of water application (100% , 85% , 70% , and 50% ETc) with three irrigation intervals (3, 5 and 7 days).The experimental design used in this study was randomized complete block design (RCBD) with three replications. Irrigation depth was monitored using a parshall flume with an opening having 3 inch throat width. The analysis of variance for the result of the study indicated significant (P < 0.05) differences for yield, above ground biomass and WUE. The highest yield (2202.2 kg/ha) was obtained under treatments which received 100% ETc with 3 day irrigation interval, while the lowest yield (1220.2 kg/ha) was obtained under treatment which received 50% ETc with 7 day irrigation interval. In terms of crop yield and water use efficiency, 50% ETc deficit irrigation application with 3 day irrigation interval gave the highest CWUE of 0.54 kg/m3 and FWUE of 0.38 kg/m3 , while the lowest value of CWUE was 0.32 kg/m3 and FWUE was 0.26 kg/m3 were obtained under100% ETc with 7 day irrigation interval. Therefore, based on yield, above ground biomass and WUE, irrigation level of 85% ETc with 5 day irrigation interval could be recommended to achieve higher yield, above ground biomass and water use efficiency in water scarcity areaenDeficit irrigationIrrigation intervalHaricot beanwater use efficiencyThesis