The rising atmospheric CO2 concentration ([CO2]) can increase crop productivity, but there are likely to be intraspecific variations in the response. To meet future world food demand, screening for genotypes with high [CO2] responsiveness will be a useful option, but there is no criterion for high [CO2] responsiveness. We hypothesized that the Finlay–Wilkinson regression coefficient (RC) (for the relationship between a genotype's yield versus the mean yield of all genotypes in a specific environment) could serve as a pre-screening criterion for identifying genotypes that respond strongly to elevated [CO2]. We collected datasets on the yield of 6 rice and 10 soybean genotypes along environmental gradients and compared their responsiveness to elevated [CO2] based on the regression coefficients (i.e. the increases of yield per 100 µmol mol−1 [CO2]) identified in previous reports. We found significant positive correlations between the RCs and the responsiveness of yield to elevated [CO2] in both rice and soybean. This result raises the possibility that the coefficient of the Finlay–Wilkinson relationship could be used as a pre-screening criterion for [CO2] responsiveness.