Evaluation and optimization of wheat and maize national evaluation systems in Europe

Wheat and maize productivity gains depend on accurate estimates of genetic trends, genotypic effects (G), and genotype-by-environment interactions (GEI). Here, we compiled a unique European Value for Cultivation and Use (VCU) database for wheat and maize (2003–2018) to estimate genetic trends, G and GEI magnitudes, and variety-testing precision in grain yield using mixed-model methodology. We found that G and GEI variances were comparable across Europe, with variety-comparison precisions of 0.29–0.56 t ha ^-1 (wheat) and 0.38–0.81 t ha ^-1 (maize). Genetic trends ranged from 0.45% to 1.81% yr ^-1 (wheat) and 0.90% to 1.31% yr ^-1 (maize). Stronger GEI corresponded with larger genetic trends in maize yield, while GEI magnitude provided an upper bound for the wheat genetic trend. Current European VCU networks are well-optimized for location numbers given national testing periods of 2–3 years. Connecting national VCU systems can increase precision, with further improvements from genotypic and environmental characterizations.