Comparison of two potato simulation models under climate change. II Application of climate change scenarios.

The effects of climate change (for the year 2050 compared to ambient climate) and change in climatic variability on potato growth and production at 6 sites in Europe were calculated. These calculations were done with both a simple growth model, POTATOS, and a comprehensive model, NPOTATO. Comparison of the results from both models indicated the sort of climate change conditions in which model results differed and may become less reliable. The effectiveness of possible management responses to climate change and the uncertainty in the model results were also evaluated with both models. With both models, climate change in northern Europe resulted in moderate to strong tuber yield increases in Jokioinen, Finland, and Tylstrup, Denmark, and in almost no yield change in Oxford, UK, both with and without irrigation. NPOTATO calculated for climate change in central and southern Europe nil to slight decreases in irrigated yield for the HCGG climate change scenario and nil to moderate yield increases for the HCGS scenario, and variable changes in water-limited yield for the HCGG scenario and slight to moderate yield increases for the HCGS scenario. POTATOS calculated less positive or more negative changes in both irrigated and waterlimited yield by climate change in central and southern Europe than NPOTATO. With both models, changes in climatic variability did not result in changes in both irrigated and water-limited yields in Europe. The management response analyses showed that both cultivation of an earlier crop variety and an advanced planting date resulted in higher yields and in more positive or less negative yield change due to climate change, in particular in southern Europe, and that only in the case of an earlier planting date did irrigation requirements always decrease with climate change. This pointed to the need for advancing the planting date with climate change. The uncertainty analyses showed that the yield change due to climate change was practically not affected by the soil type, but that this yield change may become different when a different growth model is applied, a different planting date is chosen, or a different crop variety is used