Nutritional Stability of Bambara Groundnut Mutant Lines under Waterlogging Stress: Proximate Composition and Energy Density Responses

Abstract

Background: Water logging is an increasing challenge in many Nigerian farming systems, particularly in flood-prone and poorly drained areas. In addition to reducing crop yield, waterlogging can affect the nutritional quality of food crops by altering seed composition. Bambara groundnut (Vigna subterranea) is an important indigenous legume valued for its balanced nutrient content and potential to improve household nutrition, yet information on its nutritional response to water logging stress is limited. Objectives: This study assessed the effects of waterlogging stress on the proximate composition and energy value of colchicine- and phytogenic silver nanoparticle (AgNP)-derived Bambara groundnut mutant lines, with emphasis on nutritional quality. Materials and Methods: Water logging stress was imposed at the flowering stage by maintaining 0.5–1.0 cm standing water above the soil surface for 10 days. Seeds harvested at maturity were analyzed for moisture, ash, crude protein, crude fiber, lipid, carbohydrate and calorific value using standard AOAC methods. Data were analyzed using one-way ANOVA (p < 0.05) with Tukey’s test, and multivariate analyses were used to examine relationships among nutritional traits. Results: Water logging significantly influenced seed proximate composition across genotypes and treatments. The combined treatment PTG01 (0.025% colchicine + 20 mg/L AgNP) recorded the highest moisture (≈10.41%), lipid (≈10.38%) and calorific value (≈1575.13 kJ/100 g), indicating better retention of energy-rich nutrients under stress. The highest protein content was observed in MOK01 (0.05% colchicine) (≈24.90%), alongside elevated crude fiber (≈9.10%). In contrast, PTG01 (0.05% colchicine + 40 mg/L AgNP) recorded the lowest protein content (≈18.36%). Multivariate analysis separated the mutant lines into energy-dense and protein–fiber-enriched nutritional groups. Conclusion: Overall, water logging-induced nutritional changes were genotype- and treatment-dependent, with distinct protein–fiber–enriched and energy-dense seed profiles emerging among the mutant lines. These outcomes demonstrate the potential of Bambara groundnut to contribute meaningfully to dietary protein adequacy and household energy supply in flood-prone Nigerian agro-ecologies, reinforcing its relevance for food and nutrition security.