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Deciphering field-based evidences for crop allelopathy in weed regulation

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Inès Mahé
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Bruno Chauvel
Nathalie Colbach
Stéphane Cordeau
Antje Reiss
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It is now essential to reduce the negative impacts of weed management and especially herbicide use. Weed-suppressive crop species/varieties hold promise for integrated and sustainable weed regulation. Competition for resources and allelopathy are the two main underlying mechanisms. Unlike competition, which is well studied and established, allelopathy by living crops remains a contentious mechanism. Although it is recognized that plants emit a large number of substances, the effective role of these molecules is very challenging to demonstrate in the field. A major difficulty to dissociate the effects of allelopathy from those of competition for resources. Here we systematically and quantitatively review the literature, searching for field-based evidence of the role of allelopathy (by root exudation of living crops) in weed regulation, independently of competition. A focus is made on studies comparing different varieties of a given species, in order to help disentangling the effects of allelopathy from those of competition. Our critical literature analysis also aims to identify weaknesses and strengths in methodology, providing insights on optimal experimental designs and avenues for future research. Our analysis shows that, in most articles, the role of crop competition is disregarded or not exhaustively studied. Consequently, contrary to authors’ conclusions, it cannot be determined whether weed regulation is due to allelopathy and/or competition. Overall, only 25 articles studied the differential effects of crop varieties on weed pressure in the field, explicitly considering allelopathy and competition. Among them, 13 articles considered that both allelopathy and competition explained varietal differences in weed regulation in the field, and five articles identified allelopathy as the only explicative mechanism. In order to assess an effective role of allelopathy, we conducted a detailed analysis of these 18 articles reporting an effect of allelopathy (alone or combined with competition). We combined a qualitative (relevance of experimental designs and protocols) and quantitative approach (range of variation of the measured variables, correlation analysis). Among these articles, only seven could provide convincing field-based evidence of allelopathy. The most convincing evidence was provided when combining several methods (field measurements on weeds and crop varieties and assessment of allelopathic potential in field or laboratory, linked by a multiple regression), when results are consistent. However, although these seven articles were convincing, we discussed some methodological weaknesses.129 To further investigate allelopathy in the field we recommend to (i) finely characterize crop competition by measuring traits in the field, (ii) assess crop allelopathic potential with Complementary experiments in controlled conditions or by quantifying allelochemicals in the field, and (iii) quantify the contribution of each studied trait/mechanism in explaining weed regulation in the field with multiple regression models. The consistent use of the suggested guidelines, as well as alternative approaches (e.g. creation of varieties with altered allelopathic compounds production, development of process-based simulation models) may provide a basis for quantifying the role of allelopathy in the field and, subsequently, for designing weed management strategies promoting weed biological regulation. Funding: INRAE, COPRAA project (which was supported by OFB as part of the Ecophyto call launched by the French Ministries in charge of Ecology, Agriculture, Health and Research) and Partnership Hubert Curien (PHC) – Germaine de Staël Reference: Mahé I, Chauvel B, Colbach N, Cordeau S, Gfeller A, Reiss A, Moreau D (in press) Deciphering field-based evidences for crop allelopathy in weed regulation. A review. Agronomy for Sustainable Develop
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hal-03898066 , version 1 (14-12-2022)


  • HAL Id : hal-03898066 , version 1


Inès Mahé, Bruno Chauvel, Nathalie Colbach, Stéphane Cordeau, Aurélie Gfeller, et al.. Deciphering field-based evidences for crop allelopathy in weed regulation. XVII. Congress of the European Society for Agronomy, Aug 2022, Potsdam, Germany. ⟨hal-03898066⟩
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