Crop Adaptation: Weedy and Crop Wild Relatives as an Untapped Resource to Utilize Recent Increases in Atmospheric CO₂

Adaptation measures are necessary to ensure the stability and performance of the food supply relative to anthropogenic climate change. Although a wide range of measures have been proposed (e.g., planting dates, crop choices, drought resistance), there may be a ubiquitous means to increase productivity relatively quickly. Numerous studies have shown that the projected increase in atmospheric CO₂ can stimulate crop growth and seed yield with noted intra-specific differences within crop cultivars, suggesting potential differences to CO₂ that could be exploited to enhance seed yield in the future. However, it is worth emphasizing that atmospheric CO₂ has already risen substantially (≈27% since 1970) and that, at present, no active effort by breeders has been made to select for the CO₂ increase that has already occurred. In contrast, for weedy or crop wild relatives (CWR), there are indications of evolutionary adaptation to these recent increases. While additional steps are needed, the identification and introgression of these CO₂-sensitive traits into modern crop cultivars may be a simple and direct means to increase crop growth and seed yield.