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Abstract Era studies are important to understand historical changes in maize ( Zea mays ) germplasm and estimate genetic gains, yet information for short‐season maize hybrids is limited. Here, we determine grain yield genetic gain in Bayer short‐season hybrids (100–105 days) and investigate indirect changes made on 17 secondary traits, including yield components (kernel number, weight, and shelling efficiency), and grain quality traits (oil, protein, starch, ethanol, moisture, and test weight). We evaluated 40 maize hybrids released from 1980 to 2020 across 18 environments in the US Corn Belt. Plant density and N‐fertilizer were held constant within each environment. Results indicated a linear increase in grain yield (from 11.1 to 15.3 Mg ha −1 , 105 kg ha −1 year −1 , or 0.8% year −1 ) with no sign of a plateau. The increase in grain yield was attributed more to increased kernels per m 2 (0.57% year −1 ) than kernel weight (0.23% year −1 ). Grain protein concentration decreased until the late 2000s and plateaued thereafter, while starch and ethanol concentration increased until the early 2000s and plateaued thereafter. However, the total amount of protein, starch, and ethanol increased linearly from 1980 to 2020. We concluded that maize breeding for increased grain yield has indirectly affected many traits at different rates and directions. Our results are encouraging for future progress in grain yield increase, update genetic gain information to 2020 for short‐season hybrids, and can inform plant breeders, crop physiologists, agronomists, and crop modelers.
King et al. (Wed,) studied this question.