Phenotypic characterization and multivariate analysis of diverse oat ( <i>Avena sativa</i> L.) germplasm under spring conditions in Korea: Implications for breeding programs

Abstract Oats ( Avena sativa L.) are cultivated worldwide for food and feed. Recently, there has been a growing interest in oats in South Korea owing to their nutritional and feed value. To support efficient breeding and genetic resource management, this study evaluated seven agronomic traits of 506 Avena accessions collected globally with two Korean oat varieties as standards. Seven agronomic traits – days to heading (DTH), plant height (PH), plant type, dehulling characteristics, 1,000-grain weight (TGW), seed length, and seed width (SW) – were evaluated over two to three years under Korean spring conditions. An augmented design was employed due to a lack of seeds and the field, and environmental bias was adjusted using Best Linear Unbiased Predictions. Statistical analyses revealed a strong positive correlation between TGW and SW and a moderate positive correlation between PH and DTH. Principal component analysis (PCA) identified that the first two principal components (PCs) explained 66.88% of the total variance, and that PC1 and PC2 were highly correlated with grain characteristics. K-prototype clustering analysis classified the 506 oat genetic resources into four distinct clusters based on the results of PCA, rather than their geographical origins. Cluster analysis indicated that Clusters 1 and 3 have potential for forage oat breeding, particularly in fodder use, whereas Clusters 2 and 4 may be valuable for grain-use oat breeding in South Korea. This study provides a comprehensive phenotypic assessment of oat germplasm obtained globally under Korean spring conditions and provides a useful foundation for germplasm management, cultivar development, and future genetic research.