A tale of two eras: assessing the impact of breeding programs on historical and modern German wheat cultivars under distinct management

Breeding advancements have significantly improved grain yield over recent decades, yet further progress is needed to meet global food demands amid a growing population. In this study, we systematically examine the responses of both historical and modern winter wheat cultivars, released between 1895 and 2007 in Germany, to varying management intensities. We quantified the independent contributions of nitrogen (N) levels, growth regulators, and plant protection measures to crop productivity and growth variables over two growing seasons. Historical cultivars (pre-1960) exhibited a lower yield (4.6 t ha−1) and harvest index (0.30) compared to modern cultivars (post-1960), which demonstrated a higher yield (6.8 t ha−1) and harvest index (0.40) across all treatments, even those excluding both nitrogen and agrochemicals. We found positive trends in the yield and yield components for both historical (1895–1960) and modern (1961–2007) cultivars; however, significance was only noted for modern cultivars. Crop growth in historical cultivars was aided more by growth regulators, while modern cultivars gained more benefits from plant protection. However, both categories of cultivars produced a synergistic response when combining agronomic practices. Based on a comparison of N application rates and agronomic practices, N had a distinctly greater impact on yield and yield components than other treatments. In both historical and modern cultivars, grain number per ear was the most influential contributing factor to yield. Nevertheless, the effect of the thousand grain weight on yield was notably less for modern cultivars compared to their historical ones. Grain nitrogen yield increased up to mid-supply nitrogen application but remained constant at high rates. Results underscored that cultivar-specific responses for yield and yield components need to consider the interactions between fertilization and other agronomic practices.