The Response of Three Sweet Potato Cultivars to Varying Levels of Nitrogen

Abstract

Three sweet potato ( Ipomoea batatas Lam.) cultivars that varied in vine length were compared at 5 N levels. Increasing N levels increased weight and the percentage of No. 1 grade roots of all cultivars. Vine length did not have a linear effect on yield. The long-vine ‘Centennial’ out-yielded the other cultivars, followed by the short-vine ‘L3-243’ and the intermediate-vine length ‘Goldrush’. N applications linearly increased dry matter, carotenoid (fresh and processed), protein content, and reduced fiber content of all cultivars. Cultivars varied significantly for each quality variable studied with the exception of protein content (fresh wt basis), including dry matter, carotenoids, fiber, firmness, and split roots after processing. N applications had no influence on soil P, K, Ca, Mg, or pH. Organic matter content of the soil was increased slightly by increased N applications, probably as a result of excessive vine growth, which was incorporated into the soil after harvest.