Maintenance breeding and breeding for yield potential equally contribute to genetic improvement in wheat yield

Studies that quantify the contribution of genetic improvement to crop yields typically rely on comparisons of old cultivars grown side-by-side with more recent ones. This approach, however, does not allow to distinguish gains in yield potential versus maintenance breeding that aims to keep cultivars adapted to the evolving biophysical environment, including pests, diseases, and climate change. Our analysis of long-term wheat trials from Argentina, Europe, and United States revealed an overall genetic yield improvement of 97 kg ha ^− 1 y ^− 1 (1.14% per annum) based on comparison of modern cultivars against older ‘check’ cultivars. However, nearly half of the genetic improvement (46 kg ha ^− 1 y ^− 1 ) was attributable to maintenance breeding and the other half (51 kg ha ^− 1 y ^− 1 ) to the higher yield potential of modern cultivars. We conclude that comparison of new versus old cultivars under current conditions leads to an overestimation of genetic gains in yield potential. One sentence summary : Crop yield potential gains are lower than reported.