Impact of climate change on yield and water use efficiencies of potato in different production regions of South Africa

Abstract

In South Africa, the potato is produced in regions with different climates. Climate change is expected to result in higher temperatures, thus increasing the incidence of heat stress, but lowering the risk of frosts in mid-altitude areas. Increasing ambient carbon dioxide levels can enhance photosynthetic rates and reduce water use of potato. This study assessed the impact of climate change on potential yield and water use efficiency (WUE) in twelve potato production regions of South Africa using the LINTUL-POTATO crop model. With current planting times, simulated yields between 1 961 and 2 050 increased by 0.02 and 0.40 t ha−1 y−1 and WUE by 0.00 and 0.08 g l−1 y−1 evapotranspired. Improvements in yields and WUE were close to zero when the crop was grown in hot periods, as an increasing incidence of heat stress and higher evapotranspiration largely discounted benefits of higher CO2 levels. This was particularly the case in the interior production regions, where expected temperature increases were most severe. In many regions, potato growers are likely to respond to climate change by advancing planting time. Often a trade-off existed between maximising yield and WUE. A compromise could be achieved by planting as early as possible in the optimum spring planting window for summer crops.