Nutritional diversity and geographic structure in 45 Lagenaria siceraria accessions from southwestern Nigeria, with comparative positioning among related cucurbit seeds

Lagenaria siceraria (Molina) Standl. (bottle gourd) is an orphan cucurbit whose seeds are a culturally accepted but scientifically undercharacterised food resource in West Africa, and most existing studies focus on individual accessions or a narrow set of compositional parameters. We therefore characterised the nutritional and phytochemical diversity of 45 accessions collected across four states of southwestern Nigeria (Oyo, Ogun, Osun, Ondo) and grown at the National Horticultural Research Institute, Ibadan, across two seasons under a randomised complete block design with three field replications. Seeds were analysed for proximate composition, mineral content by atomic absorption spectrophotometry, flame photometry and vanadomolybdate spectrophotometry, and antioxidant properties using Folin-Ciocalteu, aluminium chloride colorimetric, phosphomolybdenum and DPPH assays, and data were compared with peer-reviewed values for Citrullus colocynth is, Citrullus lanatus, Cucumis melo and Cucumeropsis mannii. Crude protein varied least (CV 10.78%, range 24.31-38.60%) while total antioxidant capacity varied most (CV 117.30%, range 0.16-7.88 mg TE/g). Phosphorus dominated the mineral profile (mean 711.09 mg/100 g), and a tightly co-varying mineral block (P-K-Ca-Fe, pairwise r 0.80-0.99) was positively associated with antioxidant capacity. A two-factor ANOVA confirmed that all sixteen traits were highly significantly differentiated among accessions (p < 10⁻⁵⁵ for every trait) and that neither Year nor Accession × Year was significant for any trait. Principal component analysis explained 59.4% of the variance on PC1 + PC2, and Ward's D2 clustering resolved three functional groups of fifteen accessions each: a mineral- and antioxidant-rich cluster (C1), a tannin- and carbohydrate-rich cluster (C2) and a protein- and fat-dense cluster (C3). Cluster membership cut across all four states (PERMANOVA F = 0.97, R² = 0.066, p = 0.475), indicating accession-level rather than geographic structure. A 100 g serving from C1 accessions (e.g. OS010, OS008, OG008) delivered approximately 120% of the daily phosphorus reference, around 63% of protein and 17-20% of calcium against FAO/WHO adult reference values, although these compositional contributions should be interpreted with phytate- and tannin-mediated bioavailability in mind. L. siceraria therefore offers a competitive nutritional profile relative to related cucurbits and a defined germplasm pool for biofortification breeding.