Abstract
Balanced nitrogen (N) supply is essential for high root yield in sweet potatoes (Ipomoea potatoes [L.] Lam.). A portable chlorophyll meter can support N fertilization management. Here, we deter-mined the appropriate N sufficiency index (NSI) for sweet potato leaves to achieve the best leaf N status, plant growth, N uptake and removal, and storage root yield and quality. Experiments were c…