Application of a Portable Chlorophyll Meter to Assess the Nitrogen Sufficiency Index and Nitrogen Requirements in Sweet Potatoes

Application of a Portable Chlorophyll Meter to Assess the Nitrogen Sufficiency Index and Nitrogen Requirements in Sweet Potatoes

Balanced nitrogen (N) supply is essential for high root yield in sweet potatoes (<i>Ipomoea potatoes</i> [L.] Lam.). A portable chlorophyll meter can support N fertilization management. Here, we determined the appropriate N sufficiency index (NSI) for sweet potato leaves to achieve the b...

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Main Authors: Fabrício E. Rodrigues, Adalton M. Fernandes, Arthur V. Oliveira, Pablo F. Vargas, Emerson F. C. Souza, Politon T. P. Guedes, Ricardo T. Figueiredo, Ítala T. Guimarães
Format: Article
Language:English
Published: MDPI AG 2024-11-01
Series:Agriculture
Subjects:
<i>Ipomoea batatas</i>
SPAD index
leaf N status
N top-dressing fertilization
Online Access:https://www.mdpi.com/2077-0472/14/12/2167
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Summary:Balanced nitrogen (N) supply is essential for high root yield in sweet potatoes (<i>Ipomoea potatoes</i> [L.] Lam.). A portable chlorophyll meter can support N fertilization management. Here, we determined 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 conducted at three sites (Braúna, São Manuel, and Regente Feijó) in São Paulo, Brazil, using a randomized block design with four replicates. Treatments included a control (without N application), conventional N fertilization (50 kg ha<sup>−1</sup>), reference N fertilization (150 kg ha<sup>−1</sup>), and NSI-based N fertilization (NSI: 90% or 95%, based on the chlorophyll meter readings). Plant response to N fertilization was low, with no N deficiency observed in the conventional and chlorophyll meter-managed treatments. NSI < 90% was better than NSI < 95% for N top-dressing management, reducing N application rates by 44–66%, depending on the site. In contrast, NSI < 95% increased the N application rate without any yield benefit. Thus, monitoring N fertilization using a portable chlorophyll meter with 90% NSI can reduce N fertilization rates without negatively impacting the sweet potato root yield.
ISSN:2077-0472

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