Strategic Characterization of Functional and Nutritional Traits in Yellow, Pink, and Black Oxalis tuberosa for Next-Generation Agricultural and Industrial Applications

This study provides an integrated agronomic-functional-nutritional-bioactive characterization of three <i>Oxalis tuberosa</i> varieties (Yellow, Pink, and Black) cultivated under open-field conditions. Unlike previous studies that have typically examined isolated trait groups or single quality dimensions, this work simultaneously evaluates yield-related morphology, starch functional behavior, proximate composition, antioxidant activity, and pigment-associated color attributes within a unified experimental framework, enabling robust varietal comparison and application-oriented interpretation. The Yellow variety matured later (125 ± 2 days) and produced the highest total biomass (587 ± 32 g) and yield per plant (462 ± 28 g), with the longest tubers (8.7 ± 0.3 cm) and the greatest tuber number (12.1 ± 1.1 per plant). Functional assessments indicated that the Yellow variety exhibited superior swelling capacity (10.2 g/g) and solubility index (6.3%), together with the highest starch content (68.4 ± 2.1 g/100 g DW). Nutritional profiling further showed lower moisture and higher carbohydrate levels in the Yellow variety compared with the other varieties, supporting its suitability for food processing and agricultural production. In contrast, the Black variety showed the strongest antioxidant potential, with higher DPPH scavenging activity (46.2 ± 1.3%), total phenolics (5.9 ± 0.3 mg GAE/g DW), and flavonoids (2.3 ± 0.1 mg QE/g DW), consistent with its darker pigmentation and greater nutraceutical potential. The novelty of this study lies in its integrated, multi-trait comparison of oca varieties under the same open-field conditions with standardized agronomic management, allowing for the first simultaneous assessment of agronomic performance, starch functionality, nutritional quality, antioxidant capacity, and color attributes. Overall, these findings highlight the importance of varietal selection in determining agronomic performance, starch functionality, nutritional composition, and bioactive traits in <i>Oxalis tuberosa</i>, providing actionable evidence for targeted agricultural and industrial applications.