Unraveling Diversity in Physical and Mineral Traits of Faba Bean (Vicia faba L.) Landraces Harvested at Immature Stages

Faba bean (Vicia faba L.) is a legume valued for its nutritional properties and adaptability, yet the effects of genotypic diversity among landraces and harvest stages on its physical and mineral traits remain insufficiently explored. This study evaluated 14 faba bean genotypes, (13 landraces and one commercial cultivar), harvested at two immature stages (baby and tender), to assess variation in seed volume, biomass-related parameters, and mineral composition, and to elucidate how developmental stage and genotype jointly shape nutritional profiles. Across genotypes, seed volume increased while the fresh-to-dry weight ratio (FW/DW) decreased from baby to tender stage, reflecting progressive tissue desiccation. Mineral concentrations, except for Mo and Na, generally declined during seed development, although several landraces (H9, H12, H20, H21, and H22) maintained stable values, indicating genotypic resilience to the dilution effect. Correlation analysis revealed high positive associations among mineral concentrations (e.g., Mg–Mn, K–S, P–S) and with FW/DW, suggesting that higher tissue hydration is associated with higher mineral accumulation. Principal Component Analysis (PCA) further distinguished three clusters per harvest stage, separating mineral-rich landraces (H21, H11, H9) from those with lower concentrations (H4, H7), thus highlighting developmental reorganization and genotype-dependent mineral retention. Overall, both genotype and harvest stage strongly determined the mineral profile of immature faba beans. Landraces emerged as valuable reservoirs of mineral-rich germplasm, while simple physical metrics such as FW/DW may serve as practical and economical proxies for mineral quality in breeding programs.