A study of genetic progress due to selection reveals a negative effect of climate change on bread wheat yield in France
Résumé
In France, a stagnation of bread wheat yield has been observed since the middle of the 1990s, and the possibility of a decline in breeding progress has been questionned. To investigate this hypothesis, we have considered 2 independent long time series of yield data: one corresponding to the registration trials conducted in France from 1976 to 2010, and the other corresponding to trials from the INRA bread wheat breeding program along the 1970-2010 period. These raw data related to potential bread wheat yield in France, exhibited the same trend to stagnation as observed on national yield in the farms. However, after correction of the "year" effects, the corrected yields appeared to have increased regularly from the 1970s up to now, with quite a high rate in intensive conditions (from 0.065 t ha(-1) yr(-1) to 0.137 t ha(-1) yr(-1)). This linear trend for genetic progress was even higher without fungicide (from 0.097 t ha(-1) yr(-1) to 0.158 t ha(-1) yr(-1)), which could indicate that breeding efforts for productivity and for resistance to diseases tended to have additive results. The corrected yields also enabled us to point out a marked degradation of the agro-climatic potential of the different years. As our registration and breeding trials were as free as possible from agronomic limiting factors, it appeared that climatic factors constituted the main explanation to this degradation. Thus, our study demonstrated that since the end of the 1980s, genetic progress has been partly or totally counterbalanced by the adverse effects of climate change. (C) 2012 Elsevier B.V. All rights reserved.