Phenotypic Characteristics of Quantitative Traits in an Everbearing Strawberry F₁ Population

Everbearing strawberry cultivars provide fruit during the summer–fall period when June-bearing strawberries are unavailable, but their breeding progress has been constrained by complex trait interactions. To characterize segregation patterns and evaluate phenotypic diversity, we developed an F₁ population from a cross between two everbearing cultivars, ‘Charlotte’ and ‘Flamenco’. Twenty selected progenies were evaluated for 30 quantitative traits encompassing vegetative vigor, inflorescence structure, fruit morphology, firmness, and biochemical composition. Substantial variation was observed among lines, with several individuals exceeding parental performance for key traits such as fruit size, soluble solids content, and sucrose accumulation. Principal component analysis revealed three major axes of variation: fruit composition (sugars and acids), vegetative vigor, and fruit size and morphology. K-means clustering grouped the progeny into three phenotypic classes, representing high-sugar, large-fruited, or vigorous growth types. Notably, some lines combined favorable attributes across classes, such as high sweetness and large fruit, indicating the potential to overcome typical trade-offs between yield and quality. These findings provide a practical framework for breeding selection and highlight superior progeny as immediate candidates for clonal advancement or as parents in future crossing. The results also establish a foundation for integrating phenotypic classifications with molecular tools to accelerate the development of high-value everbearing strawberries.