Yield levels of potato crops: Recent achievements and future prospects

The potential yield of potato is defined as the theoretical yield that can be assessed for a well-adapted cultivar, grown from the best possible seed under optimal conditions. More than in crops that are grown from generative seeds, the growth, development, yield and quality of the potato crop are strongly influenced by the quality of the seed tubers, including their genetic, physical and physiological quality and their seed health status. Potato is very variable in maturity type: late cultivars can intercept large quantities of light whereas early cultivars show more efficient resource use. We describe potential and actual yields as well as impact of climate change on these yields, based on simple, robust models. Potential yields may be as high as 160 Mg ha−1, in production systems with abundant irrigation, high radiation levels and long seasons. In such systems, actual yields of above 120 Mg ha−1 are feasible. However, potato is also grown as a short-cycle crop and in those conditions potential and actual yields are much lower. Potential yields might not change much in potato over time, but there is still a large gap between actual and potential yields to fill. The ratio between actual and potential yield ranges from 10 to 75%, but typical values are between 30 and 40%, although they obviously depend on the level of input. These ratios allow great yield improvements provided inputs are economically feasible in practice and if climate change does not interfere. In most countries, yields of potato might increase by climate change, provided water supply remains adequate. Main changes through climate change will probably occur by changes in the number of growing days per crop cycle. In some areas with abundant potato production, such as the Indo-Gangetic plains, however, climate change might reduce yield because of a reduction in number of growing days, but it has been projected that the effects of climate change on potato will be regionally diverse.