An in‐depth historical phenotypic and genetic assessment of oat ( Avena sativa L.) breeding at the University of Illinois

It is essential to evaluate the effectiveness of breeding programs to ensure they continue to deliver value to stakeholders, including farmers, millers, and consumers. We evaluated the performance of the University of Illinois Oat Breeding Program (UIOBP) by quantifying realized genetic trends for key agronomic, grain quality, and disease resistance traits. Additionally, we assessed the effect of heat stress and genetic diversity to inform future breeding decisions. Our analysis integrated genotypic, pedigree, historical weather, and phenotypic data collected over an 18‐year period from 2002 to 2019. Genetic trends were estimated using mixed models and the control population method. We quantified genetic correlations, rates of genetic gain, and the effects of temperature on yield and test weight, and assessed genetic diversity using molecular marker data, pedigree reconstruction, and population structure. Significant genetic trends were observed for yield (35.8 kg ha − 1 year − 1 ), test weight (0.63 g L − 1 year − 1 ), heading date (−0.01 days year −1 ), and plant height (−0.07 cm year − 1 ), while barley yellow dwarf virus, groat content, and thins (%) showed no significant change. Genetic diversity analyses revealed weak population structure and slightly reduced effective population size in recent parental lines. Phenotypic analyses showed that high temperatures during critical reproductive periods reduced yield and test weight. The UIOBP has maintained genetic diversity while achieving favorable selection response in yield, test weight, heading time, and plant height; however, limited progress in milling traits highlights areas for improvement. These findings demonstrate the continued value of public oat breeding while informing future breeding efforts.