The trade-off between qualitative and quantitative trait in forage oat (Avena sativa L.) genotypes

Oat forage represents a critical feed source in agricultural systems, where the relationship between quantitative traits and nutritional value plays a fundamental role in crop optimization and livestock nutrition. This study explores the genetic diversity and examines the relationship between quantitative and qualitative traits among thirteen oat genotypes, in two cropping seasons (2021–2023) at the Seed and Plant Improvement Institute in Karaj, Iran. A randomized block design was employed to assess quantitative and Qualitative traits. Significant genotypic variation was identified, with genotype 9 demonstrating superior forage yield and genotype 1 excelling in protein content. Genotype-by-year interactions notably influenced traits like flowering time and plant height, reflecting environmental effects. Correlation and principal component analyses revealed key trade-offs, such as a negative correlation between dry forage yield and protein content, and positive associations between flag leaf length and forage quality traits. Cluster analysis grouped genotypes by performance, highlighting promising candidates for breeding initiatives. Path analysis revealed that plant height (C = 0.54) and days to flowering (C = 0.43) are the strongest direct determinants of fresh forage yield, while flag leaf traits and panicle length exert weak or negligible effects. These results underscore the potential of oat genetic resources to simultaneously improve forage yield and nutritional quality, thereby advancing sustainable agriculture and enhancing food security.