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Grant support

We would like to thank Catedra Adama and the Spanish Weed Science Society (SEMh) for providing financial support for this project. We are grateful to the many students and technicians who assisted with fieldwork at the different experimental locations. We would like to thank the Spanish government for partial funding, through project AVA 2019.020 Advances in Technological Research in Winter Cereals: Genetic Improvement and Sustainable Management, financed with Fondo Europeo de Desarrollo Regional (FEDER) funds (80%). Also, JT acknowledges support from the Spanish Ministry of Science, Innovation and Universities (grant Ramon y Cajal RYC2018-023866-I). We thank Enrique Chamber for installing and maintaining the data loggers at the various locations. No conflicts of interest have been declared.

Analysis of institutional authors

Mari León, Ana IsabelAuthor

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June 12, 2020
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Article
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Modeling the emergence of North African knapweed (Centaurea diluta), an increasingly troublesome weed in Spain

Publicated to:Weed Science. 68 (3): 268-277 - 2020-05-01 68(3), DOI: 10.1017/wsc.2020.22

Authors: Sousa-Ortega, Carlos; Royo-Esnal, Aritz; DiTommaso, Antonio; Izquierdo, Jordi; Loureiro, Inigo; Mari, Ana I; Cordero, Fernando; Vargas, Manuel; Saavedra, Milagros; Paramio, Jose A; Fernandez, Jose L; Torra, Joel; Urbano, Jose M

Affiliations

ADAMA Agr Espana SA, Madrid, Spain - Author
Assoc Invest Mejora Cult Remolacha Azucarera, Valladolid, Spain - Author
Cornell Univ, Sch Integrat Plant Sci, Sect Soil & Crop Sci, Ithaca, NY USA - Author
CSIC, Toledo, Spain - Author
Ctr Invest & Tecnol Agroalimentaria, Dept Sanidad Vegetal, Zaragoza, Spain - Author
Field Trial Serv Agroconsulting, Seville, Spain - Author
Inst Invest & Formac Agr & Pesquera, Protecc Cult, Cordoba, Spain - Author
Inst Nacl Invest & Tecnol Agr & Alimentaria, Dept Sanidad Vegetal, Madrid, Spain - Author
Univ Lleida, Escuela Tecn Super Ingn Agron, Dept Hortofruticultura Bot & Jardineria, Lleida, Spain - Author
Univ Politecn Cataluna, Dept Engn Agroalimentaria & Biotecnol, Barcelona, Spain - Author
Univ Seville, Dept Ciencias Agroforestales, Escuela Tecn Super Ingn Agron, Seville, Spain - Author
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Abstract

North African knapweed (Centaurea diluta Aiton) is an annual weed that is widespread in southern Spain and is of increasing concern in dryland cropping systems. Despite its expanding range in Spain, there is limited information on the emergence timing and pattern of this species, knowledge of which is critical for developing more timely and effective management strategies. Therefore, there is a need to develop simple and reliable models to predict the timing and emergence of this annual weed under dryland conditions. A multi-location field experiment was established across Spain in 2016 to 2017 to assess the emergence of C. diluta. At each of 11 locations, seeds were sown in the fall, and emergence was recorded. Overall emergence averaged 39% in the first year across all sites and 11% in the second year. In both years, the main emergence flush occurred at the beginning of the growing season. A three-parameter Weibull function best described seedling emergence of C. diluta. Emergence models were developed based on thermal time (TT) and hydrothermal time (HTT) and showed high predictability, as evidenced by root mean-square error prediction values of 10.8 and 10.7, respectively. Three cardinal points were established for TT and HHT at 0.5, 10, and 35 C for base, optimal, and ceiling temperatures, respectively, while base water potential was estimated at -0.5 MPa.

Keywords

Dimorphic achenesFutureGerminationHydrothermal modelHydrothermal timeNorth african knapweedPeriodRmsepSeedling emergenceSeedling emergence modelSolstitialisThermal modelWeibull

Quality index

Bibliometric impact. Analysis of the contribution and dissemination channel

The work has been published in the journal Weed Science due to its progression and the good impact it has achieved in recent years, according to the agency WoS (JCR), it has become a reference in its field. In the year of publication of the work, 2020, it was in position 21/91, thus managing to position itself as a Q1 (Primer Cuartil), in the category Agronomy.

From a relative perspective, and based on the normalized impact indicator calculated from the Field Citation Ratio (FCR) of the Dimensions source, it yields a value of: 2.75, which indicates that, compared to works in the same discipline and in the same year of publication, it ranks as a work cited above average. (source consulted: Dimensions Sep 2025)

Specifically, and according to different indexing agencies, this work has accumulated citations as of 2025-09-18, the following number of citations:

  • WoS: 11
  • Scopus: 12

Impact and social visibility

From the perspective of influence or social adoption, and based on metrics associated with mentions and interactions provided by agencies specializing in calculating the so-called "Alternative or Social Metrics," we can highlight as of 2025-09-18:

  • The use, from an academic perspective evidenced by the Altmetric agency indicator referring to aggregations made by the personal bibliographic manager Mendeley, gives us a total of: 15.
  • The use of this contribution in bookmarks, code forks, additions to favorite lists for recurrent reading, as well as general views, indicates that someone is using the publication as a basis for their current work. This may be a notable indicator of future more formal and academic citations. This claim is supported by the result of the "Capture" indicator, which yields a total of: 15 (PlumX).

With a more dissemination-oriented intent and targeting more general audiences, we can observe other more global scores such as:

  • The Total Score from Altmetric: 1.
  • The number of mentions on the social network X (formerly Twitter): 2 (Altmetric).

It is essential to present evidence supporting full alignment with institutional principles and guidelines on Open Science and the Conservation and Dissemination of Intellectual Heritage. A clear example of this is:

  • The work has been submitted to a journal whose editorial policy allows open Open Access publication.

Leadership analysis of institutional authors

This work has been carried out with international collaboration, specifically with researchers from: United States of America.