2026-06-27http://hdl.handle.net/123456789/127108This dataset contains phenotypic field evaluation data generated from a germplasm collection assessed under Ethiopian highland agroecological conditions. The study was conducted as part of ILRI–CGIAR research activities focusing on forage and grain quality, improvement, climate resilience, and accelerated breeding for livestock feed systems in Eastern Africa. The dataset includes phenotypic, and nutritional measurements collected from diverse oat accessions evaluated across experimental environments and/or growing seasons. Traits recorded include agronomic performance, biomass production, grain yield, forage-related characteristics, and quality-associated traits. The dataset also include morphological descriptors and related experimental observations used for genetic analysis and breeding applications. The data were generated to support: genetic diversity and population structure analysis, genome-wide association studies (GWAS), marker–trait association studies, genomic selection and breeding applications, forage and grain quality improvement research, climate-resilient crop development for mixed crop–livestock systems. Researchers, breeders, students, and agricultural development practitioners may use the dataset for comparative analyses, breeding program support, statistical modelling, genotype evaluation, and integrative genomics research in oats and related forage crops. The dataset is provided in Microsoft Excel (.xlsx) format and contains curated phenotypic observations for further analyses.Limited Accesscrop improvementforage cropsgermplasmplant breedingplant genetic resourcesoatsclimate resiliencegenomic selectionlivestock feedsustainable agricultureagricultural researchagronomic traitsfeed resourcesfield trialsexperimental dataavena sativaoat (avena sativa)marker–trait associationbiomass yieldquantitative traitsphenotypic traitsgrain qualityhighland agriculturegenetic diversitygenome-wide association study (gwas)forage qualitytropical foragesmixed crop–livestock systemsDataset