Profiling Proximate and Mineral Variability in Nigerian Turmeric (Curcuma longa L.) Genotypes: Implications for Breeding and Biofortification

Turmeric (Curcuma longa L.) is valued not only as a spice but also for its nutritional and medicinal properties. Enhancing its nutrient content through targeted breeding can contribute to dietary diversification and food security. This study aimed to assess the nutritional and mineral variability of eight Nigerian turmeric genotypes to identify promising accessions for crop improvement and biofortification. Field trials were conducted in 2024 cropping season at the University of Calabar, Calabar, using a Randomized Complete Block Design with three replications. Proximate and mineral analyses of leaves and rhizomes were performed, and trait variability and genetic relationships were evaluated using analysis of variance, principal component analysis, and cluster analysis. Significant differences were observed among genotypes for most traits. Rhizomes contained 72.34–75.38% carbohydrates, 4.11–5.12% crude protein, 4.93–6.79% crude fat, and calorific values of 362.14–371.85 kcal. Mineral contents varied significantly; calcium (29.66–41.37 mg/100 g), magnesium (70.61–113.13 mg/100 g), phosphorus (14.38–23.02 mg/100 g), potassium (30.12–43.61 mg/100 g), and zinc (2.31–3.84 mg/100 g). Leaves were rich in carbohydrates (83.79–85.76%), contained 3.42–4.36% crude protein, and had calorific values of 374.88–386.36 kcal. Principal component analysis revealed that mineral traits were major contributors to genetic variation, and cluster analysis categorized accessions into mineral-rich, balanced, and carbohydrate-rich groups. The study demonstrates considerable genetic diversity among Nigerian turmeric genotypes, offering a strong foundation for breeding nutrient-rich and energy-rich cultivars for functional foods and improved dietary quality.