IMPACTS OF CLIMATE CHANGE ON BREAD WHEAT (Triticum aestivum L.) PRODUCTION AND ADAPTATION STRATEGIES IN ADET, NORTH WESTERN ETHIOPIA

Abstract

Earth‘s climate is undergoing changes. Thus, quantifying the extent and direction of climate change and its impacts on crop production is important to identify adaptation options at local level. The aim of this study was to assess the climate change impact on bread wheat (Tay and Senkegna varieties) production and suggesting adaptation measures in response to future climate in Adet, North Western Ethiopia. The observed daily climate data (rainfall, minimum and maximum temperatures, wind speed, relative humidity, and solar radiation) were obtained from Ethiopian National Meteorological Agency, Bahir Dar branch for 33 years (1983 - 2015). Future climate data were generated from Climate Research Programme‘s Fifth Coupled Model Intercomparison Project (CMIP5) database across 20 GCMs for RCP4.5 and RCP8.5 emission scenarios in the time horizon of early-term (2010 - 2039), mid-century (2040 - 2069) and end-century (2070 - 2100). Carbon dioxide concentration for baseline, 380 ppm; near term under RCP4.5, 423 ppm; near term under RCP8.5, 432 ppm; midterm under RCP4.5, 449 ppm; midterm under RCP8.5, 571 ppm; end term under RCP4.5, 532 ppm, and end term under RCP8.5, 801 ppm were used. Crop and soil data were obtained from Adet Agricultural Research Center. The onset, end dates, LGP, and dry spell risk for the main rainy season were analyzed using first-order Markov model built in INSTAT tools version 3.36. Decision Support System for Agro-technology Transfer (DSSAT) crop model was employed during CSM-CERES-wheat model calibration, validation and yield simulation, as well as in determining the best adaptation measures to wheat production. From the results; the onsets of the rainy seasons occurred before 1st dekad of June were in only 25% of the years while occurred before 2nd dekad of June were in 75% of the years with coefficient of variation was 5.3%. The end date of the rainy seasons occurred before 1st dekad of November were in only 25% of the years, and occurred before 2nd dekad of November were in 75% of the years with coefficient of variation was 3.7%. Length of Growing Period (LGP) had minimum and maximum value of 125 and 185 days respectively with the coefficients of variation was 9%. The observed rainfall was decreased while both maximum and minimum temperatures were increased significantly (P-value<0.05). The projected maximum temperature exhibits increasing by 2.11 - 2.690C and by 1 - 4.60C under RCP4.5 and RCP8.5 respectively. Further, it could be noted minimum temperature increases by 2.16 - 2.860C under RCP4.5 and by 0.93 - 4.730C under RCP8.5 relative to the baseline. For Tay wheat, the grain yield is expected positively change by 2% in 2030s under both RCPs, and negatively change by 3% in 2080s under RCP8.5. For Senkegna wheat, the yield is also expected to change positively by 1 - 2% in each time slice under both scenarios relative to the baseline. Therefore, growing of both wheat varieties in the main rainy season under future climate condition, along with high fertilizer rate (1.84 qt ha-1) and planting time in the 3rd dekad of June (June 25) with high plant density (250 - 350 plants m-2) can insure the yield to be optimized by 50 - 52 qt ha-1 in the study area. Key words: