Effects of Different Fertilizer Application Methods on Yield and Quality of “Kenroku” Sweet Potato in Sandy Loam Fields

Abstract

The sweet potato (Ipomoea batatas (L.) Lam.) cultivar “Kenroku” has been cultivated mainly to produce steamed and dried slices. Therefore, it is necessary to improve both the size and the appearance of the storage roots. In sandy loam fields, fertilization before transplanting of cuttings significantly increased the number of storage roots, but significantly decreased the average weight of each storage root; as a result, total yield was comparable to that of cuttings grown without fertilization. In contrast, delayed fertilization at 8 weeks after transplanting significantly increased the average weight and total yield of the storage roots, although the number of storage roots decreased. In addition, the corrugations that are frequently observed on the surface of storage roots grown without fertilization were decreased by the delayed fertilization. Different fertilizer application methods did not affect the contents of sugars and β-carotene. These results strongly suggest that delayed fertilization can improve the production and quality of storage roots of “Kenroku” sweet potato.