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Several simulations predict that climate change will reduce yields, but they are all based on the assumption that the farmers of 2050 will use the same plant varieties as today. However, the agricultural profession is now planting corn varieties that are harvested later and later in the year to counter the effects of climate change. Basing itself on current professional practices and knowledge, measures taken in real conditions at several sites, and more than three million simulations of 12 climate models, researchers at the French National Institute for Agricultural Research (INRA) have shown that the exploiting genetic diversity of corn would allow for an adaptation to climate change and an increase in yields.

With corn, the length between planting and harvesting is linked to the date of flowering, and is controlled by genes that are increasingly well identified. Farmers can chose from a catalog the varieties having the earliness they need, thus adapting them to temperature variations between the north and south of Europe or those linked to climate change. In their study, the scientists of INRA took into account these adaptations to analyze the impacts of climate changes on the corn yields of Europe.

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A large genetic variability in flowering was observed among the 121 genotypes maximizing field diversity. On this basis, the researchers built a model to calculate the cycle length that maximized the yield of 59 European sites over 36 years. This length takes more time in the south than in the north of Europe, but is reduced by drought: It is better to plant a shorter cycle in dry years to keep water in the soil until harvest. According to European statistics, farmers at each site used varieties close to the simulated optimums.

The scientists then considered that the farmers of 2050 will continue to use these rules of variety choice that they are currently successfully using, and that the people making the choices could continue to provide corresponding varieties. Three million simulations calculated the yields of 2050 for varieties having the largest range of cycle lengths at each site, in 12 climate change scenarios, with several hypotheses for the crop practices and for the concentration of CO2. The predicted yields decreased with climate change if they are simulated with the varieties and practices of today, but increase if the farmer continue to exploit the genetic variability of flowering as they do now.

This study shows that genetic diversity allows for an adaptation to climate change and that farmers have the ability to adapt, and must be taken into account in climate change impact studies. One must not assume that climate change will be favorable: The study does not analyze other harmful effects of climate change such as the appearance of new diseases or the frequency of extreme climate events (floods or storms).