CHARACTERIZATION OF CLIMATE CHANGE AND MODELING ITS IMPACTS ON BARLEY (Hordeum vulgare L.)PRODUCTION IN WELMERA DISTRICT, OROMIA REGION, ETHIOPIA

In countries like Ethiopia where agriculture is dependent on rainfall, the impact of climate change on crop production is large. Understanding impact of climate change at local level and specific crop is of paramount importance. The aim of this study was to characterize climate change and model its impact on barley production in Welmera District, Ethiopia. Accordingly, historical climate data (1986-2016) was collected from Holeta Agricultural Research Center to analyze the past climate of the study area. In addition, future climate was downscaled from an ensemble of two climate models (CSIRO-Mk3-6-0 and HadGEM 2- ES) using MarkSim weather generator for the medium (RCP 4.5) and higher (RCP 8.5) emissions trajectory. INSTAT+v.3.36 software and the Mann-Kendall test and Sen’s slope estimator were employed to assess trends of rainfall and temperature variables. DSSAT V4.7 was used to simulate future change in barley yield (Holker and HB-1307) and to identify best adaptation measures in the study area. The results of this study revealed that both annual and seasonal rainfall showed a decreasing trend in the last three decades. In contrast, both maximum and minimum temperature exhibited an increasing trend for monthly, annual and seasonal rainfall. The annual minimum and maximum temperature has shown an increasing trend with a magnitude of 0.004 and 0.04 0 C per year respectively. On the other hand, projected annual and seasonal rainfall showed an increasing trend except in bega season by 2050’s under both time of slices and RCPs. More increment of rainfall will be expected in belg as compared with kiremt and bega seasons under both time of analysis and RCPs. Moreover, mean annual and seasonal maximum and minimum temperature projected to increase under both time slices and emission scenarios. The crop model simulation indicated that projected climate will have negative consequences on the yield of Holker variety except by 2080’s under RCP 8.5 while positive consequences on HB-1307 variety in both time slices and RCPs scenarios. Hence, Climate change could affect the production of barley in the study area in different time slices both in the past and in the future climatic conditions. As adaptation measures, planting windows of 15th June for Holker variety and 4thJuly for HB-1307variety found to be best adaptation measure. Planting density of 169 plants m-2 for Holker and 195 plants m-2 for HB-1307variety expected to increase the yield under projected future climatic condition of the study area. Therefore, adopting appropriate agronomic practice might reduce the impacts of climate change on the yield of barley in the study area.