Analysis of micronutrients variations among sweet potato (Ipomoea batatas [L.] Lam) genotypes in Malawi

Sweet potato (Ipomoea batatas [L.] Lam) is an important root crop in Malawi and Sub-Saharan Africa where micronutrient deficiency is an eminent health problem. Using 15 sweet potato genotypes grown in a randomized complete block design at Bvumbwe Research Station, a study was undertaken to determine the extent of variability of selected micronutrients in the genotypes as influenced by storage root age and peeling. Analysis of variance (ANOVA) showed significant (p≤ 0.01) variability among genotypes for dry mater, β-carotene, ascorbic acid levels and reduction of β-carotene due to peeling across all ages. Significant (p ≤ 0.05) variations in zinc, iron and copper were also observed among all genotypes. Peeling reduced β-carotene, ascorbic acid levels, iron, zinc and copper content while late harvesting resulted in low iron, zinc and copper. Therefore, 5 months after planting (MAP) and 4 MAP are recommended for high levels of β-carotene and ascorbic acid and iron, zinc and copper, respectively. Ten genotypes exhibited acceptable levels of dry mater of ≥30%. Zondeni (10.9 mg/100 g, WW) and Babache (23.84 mg/100 g, WW) had highest levels of β-carotene and ascorbic acid, respectively. Mzungu displayed the highest levels of Iron (0.67 mg/100 g, DW) and zinc (0.63 mg/100 g, DW) while Yoyera (0.61 mg/100 g, DW) had the highest levels of copper. Variations of various traits entail potential to breed for higher levels of micronutrients. Key words: Sweet potato, genotypes, β-carotene, ascorbic acid, iron, zinc, copper, peeling, storage root age.