Contribution of improved varieties to maize productivity under climate change in Uganda

One of the most promising pathways to enhance food security for smallholder farmers is the use of improved crop varieties to increase productivity and minimize climate risks. However, assessing the performance of improved crop varieties under climate change is difficult because of limited long-term empirical data from on-station- and farmer field trials and because future climate could be different from what has been experienced. In this study, the climate change adaptation potential of hybrid maize as an improved variety using the Decision Support System for Agrotechnology Transfer (DSSAT) model applied on grid-scale across Uganda was analysed. The DSSAT model was calibrated with observed weather data and analysed the impact of climate change on maize yield under low (SSP1-RCP2.6) and high (SSP3-RCP7.0) emission scenarios. At the national level, it is projected that a yield reduction of 9.6% (low emission scenario) and 11.8% (high emission scenario) by 2030 will occur under climate change. A yield reduction of 11.2% (low emission scenario) and 19.6% (high emission scenario) is projected by 2050, and 13.3% (low emission scenario) and 29.4% (high emission scenario) by 2090. Comparing the effect of climate change between both varieties shows that it is always better to use the hybrid variety, especially under high emission climatic conditions (8.2% and 24.6% yield buffering by 2090 under low emission and high emission scenarios, respectively) at national level. This positive yield effect is realized across all grids, but substantially varies between sites. However, in order to increase adoption of hybrid maize varieties by smallholder farmers in Uganda, adoption barriers, like access to input markets and financial services, have to be overcome. We identify some of these barriers and discuss opportunities to attenuate them and implications on the modelling results. It is concluded that hybrid maize varieties can potentially be a suitable adaptation measure against climate change-related declines in maize production in Uganda.