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
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Online Access:https://www.mdpi.com/2077-0472/14/12/2167
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author 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
author_facet 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
author_sort Fabrício E. Rodrigues
collection DOAJ
description 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.
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spelling doaj-art-150a31b3bfe246c99a98fadf871fff7a2025-08-20T02:50:56ZengMDPI AGAgriculture2077-04722024-11-011412216710.3390/agriculture14122167Application of a Portable Chlorophyll Meter to Assess the Nitrogen Sufficiency Index and Nitrogen Requirements in Sweet PotatoesFabrício E. Rodrigues0Adalton M. Fernandes1Arthur V. Oliveira2Pablo F. Vargas3Emerson F. C. Souza4Politon T. P. Guedes5Ricardo T. Figueiredo6Ítala T. Guimarães7College of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, São Paulo, BrazilCollege of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, São Paulo, BrazilCollege of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, São Paulo, BrazilCenter for Tropical Roots and Starches (CERAT), São Paulo State University (UNESP), Botucatu 18610-034, São Paulo, BrazilDepartment of Soil, Water, and Climate, University of Minnesota, St. Paul Campus, Falcon Heights, MN 55108, USACollege of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, São Paulo, BrazilCollege of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, São Paulo, BrazilCollege of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, São Paulo, BrazilBalanced 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.https://www.mdpi.com/2077-0472/14/12/2167<i>Ipomoea batatas</i>SPAD indexleaf N statusN top-dressing fertilization
spellingShingle 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
Application of a Portable Chlorophyll Meter to Assess the Nitrogen Sufficiency Index and Nitrogen Requirements in Sweet Potatoes
Agriculture
<i>Ipomoea batatas</i>
SPAD index
leaf N status
N top-dressing fertilization
title Application of a Portable Chlorophyll Meter to Assess the Nitrogen Sufficiency Index and Nitrogen Requirements in Sweet Potatoes
title_full Application of a Portable Chlorophyll Meter to Assess the Nitrogen Sufficiency Index and Nitrogen Requirements in Sweet Potatoes
title_fullStr Application of a Portable Chlorophyll Meter to Assess the Nitrogen Sufficiency Index and Nitrogen Requirements in Sweet Potatoes
title_full_unstemmed Application of a Portable Chlorophyll Meter to Assess the Nitrogen Sufficiency Index and Nitrogen Requirements in Sweet Potatoes
title_short Application of a Portable Chlorophyll Meter to Assess the Nitrogen Sufficiency Index and Nitrogen Requirements in Sweet Potatoes
title_sort application of a portable chlorophyll meter to assess the nitrogen sufficiency index and nitrogen requirements in sweet potatoes
topic <i>Ipomoea batatas</i>
SPAD index
leaf N status
N top-dressing fertilization
url https://www.mdpi.com/2077-0472/14/12/2167
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