Potato Yields Are Influenced by the Climate and Genetic Variability

Stable yields are essential to ensure agricultural profitability. Two key measures are needed to limit future losses: adapting cultivation methods to the site and selecting heat- and drought-resistant varieties.

Yield stability is important for both farmers and consumers. An analysis of potato yields in the Western Alps (French-speaking part of Switzerland) from 1990 to 2021 showed that around 50% of yield variability can be explained by the environment – including weather events and the location of the growing site. With climate change, increasing fluctuations in temperature and precipitation are expected to further affect yields in the future.

Climate-induced yield variability

Using statistical models, Agroscope researchers found that 30% of yield variability can be explained by meteorological factors, namely: water supply between tuber initiation and harvest, number of sunny days, average and maximum daily temperatures between planting and harvest. According to the model, each decrease of 1 mm in rainfall leads to a decrease in yield of 0.03 t/ha. Losses are particularly severe in periods of extreme drought. Average temperatures above 16.5 °C could reduce yields significantly: each additional degree Celsius would cause a loss of 6.4t/ha, or 14.8% less yield per degree Celcius.

Varietal choice also influences yield

The genetic variability of cultivated potatoes also has a major impact on yield – robust and productive varieties are essential. The study showed that the choice of variety can account for up to 24% of yield variability. This figure is higher than in many comparative studies, partly due to the large number of varieties tested – more than six hundred in this case. While breeding research in recent decades has focussed mainly on increasing yields, today the targeted selection of site-adapted varieties and specific agronomic measures are becoming increasingly important. This is because a higher yield often comes at the cost of tuber quality and plant stability. In the face of extreme weather events which are only likely to intensify, it is more important than ever to select stable varieties adapted to local conditions.

Starch content mainly determined by genetic variability

Genetic variability was found to explain 75% of the starch content (in % of fresh weight). Environmental factors such as temperature and precipitation explained only 4 to 6% of the variability in starch content. This implies that the starch content remains largely stable even in dry years. However, a prolonged period of drought can impact other quality characteristics such as skin quality and sugar content.

Gloomy climate predictions

Diverse climate models for Switzerland predict possible temperature rises ranging from +0.7 °C to +7.2 °C in summer by 2085. At the same time, summer precipitation could fall by 42.8%. The resulting yield losses are estimated to be as follows, depending on the scenario:

2035: –3% to –16%

2050–2060: –5.4% to –50.3%

2080: –6% to –84%.

The most significant losses – as already mentioned – are caused by heat and drought.