Evaluation of the growth, storage root yield, proximate composition, and mineral content of colored sweet potato genotypes

The storage roots and leaves of sweet potato are potential sources of human nutrition. Variations may exist in the growth, yield, and nutritional contents of different genotypes. In this experiment, the growth, storage root yield, yield-contributing traits, leaf chlorophyll (Chlo) index, anthocyanin (Antho) index, flavonoid (Flavo) index, nitrogen-balance index (NBI), proximate compositions, and mineral content of the leaves and storage roots of sweet potato genotypes were investigated to identify nutrient-rich and high-yielding sweet potato. A field experiment was performed using the randomized complete block design, and a laboratory analysis was conducted using the completely randomized design with three replicates. Significant variations were observed in the growth, yield-contributing traits, yield of storage roots, leaf indices, proximate compositions, and mineral content of both organs of sweet potato genotypes. The range of the different components were as follows: storage root yield, 2.04 ± 0.18 t/ha to 48.80 ± 12.06 t/ha; dry matter contents of the storage roots and leaves, 20.26%–35.16%, and 10.24%–16.68%, respectively; leaf Chlo index, 27.25 ± 2.12 to 34.51 ± 0.71; Flavo index, 1.10 ± 0.12 to 1.59 ± 0.05; and Antho index, 0.18 ± 0.02 to 0.21 ± 0.03. Except nitrogen-free extract (NFE) and starch, the proximate compositions and mineral contents were higher in leaves than in storage roots. The mineral content of leaves were 0.80% ± 0.01%–1.29% ± 0.03% calcium (Ca), 0.24% ± 0.01%–0.40% ± 0.01% magnesium (Mg), 5.25% ± 0.02%–6.96% ± 0.04% phosphorus (P) and 1.22% ± 0.01%–1.41% ± 0.01% potassium (K). From the findings of this study, it was indicated that leaves are a good source of protein, fiber, and minerals particularly Ca, Mg, P, and K. Thus, storage roots including sweet potato leaves can be consumed to combat malnutrition, particularly in low income groups in developing countries.