Abera Gayesa Tirfi
The objective of the study was to examine the trend and variability of climatic and yield parameters and determine impacts of weather factors influencing sorghum yield in Ethiopia. Cobb-Douglas production model, linear trend, and standardized anomalies were employed as analytical tools. Long-season rainfall demonstrated an increasing trend with magnitude of 1.19 mm/year, while short-season rainfall exhibited a decreasing trend with a magnitude of (-0.798 mm/year). Equally, maximum and minimum temperatures depicted significantly increasing trends with magnitude of 0.012 mm/year and 0.035mm/year, respectively. The increase in temperature variables supports the evidence of rising temperature recorded in many parts of the world. The study exemplified presence of moderate inter-seasonal rainfall variability, which encompasses the highest negative anomaly of 1997-98 occurred due to El Nino. The study further exemplified presence of minimal to moderate variability of maximum and minimum temperatures. The anomalies of sorghum yield exhibited variation with a magnitude ranging from +2.36 to -1.76. The high variability of sorghum yield emanates from variations experienced in climatic parameters.
The results further revealed that the elasticity of short-season rainfall had positive and significant relationship with sorghum yield. The positive elasticity implies that short-season rainfall well aligns with the critical water requirement of sorghum for sowing seeds. As sorghum is long-cycle crop, short-season rainfall is critically important for seed-bed preparation for the crop under study. Conversely, long-season rainfall showed negative impact on sorghum yield; the negative impact registered occurred due to scarcity of rainfall during critical crop growth periods which leads to wilting of leaves and stalks; inhibit proper vegetative growth; and shrinks grain filling. This infers that cultivation of sorghum in greatly depends on rainfall. Conversely, the elasticity coefficients of maximum temperature had negative and significant impact on sorghum yield. It can be judged that maximum temperature and long-season rainfall correlates in exerting harsh effect on sorghum yield. Significant increase in maximum temperature correlates with reduction in amount of main-season rainfall, leading to drought and reduction of yield. Contrastingly, crop growing period minimum temperature had positive impact on sorghum yield.
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