Objectives

The concentration of CO2 in the atmosphere has dramatically increased since the pre-industrial period and may, within the next few decades, reach 600 ppm irrespective of the ongoing policies to reduce human-based C emission. This increase is expected to promote crop yield in particular in C3 species (whose photosynthesis directly depends on external CO2 concentration) as predicted by experiments under elevated CO2 (eCO2) and model projections. However, there is also growing evidence that C3 cereals tend to be carbon sink limited under eCO2 due to the inability of sinks such as reproductive parts to benefit from additional C available, causing a downregulation of photosynthetic called acclimation. Large gains in eCO2 yield response are therefore expected if sink eCO2 responsiveness can be selected for. As costs of breeding in CO2 FACE field trials are prohibitive, proxy traits able to predict eCO2 sink response based on evaluation under current CO2 could be of high value to orientate breeding towards genotypes making the most of eCO2.