Impact of crop-weed competition on yield gap: A field-based approach in sugarcane in Réunion Island

Laine Elise, Ripoche Aude, Colbach Nathalie, Affholder François. 2024. Impact of crop-weed competition on yield gap: A field-based approach in sugarcane in Réunion Island. . Institut Agro Rennes-Angers, INRAE. s.l. : s.n., 1 Congress of the European Society for Agronomy. 18, Rennes, France, 26 Août 2024/30 Août 2024.

Résumé : In Réunion Island, herbicides are the main pesticides used in sugarcane cropping systems (Antoir et al., 2016; DAAF La Réunion, 2016). Available herbicides registered for use on sugarcane were recently reduced to 8, and should be further restricted to 4 (ANSES, 2023). However, weeds may cause yield losses ranging from 20% to over 50% (Marnotte & Le Bourgeois, 2018), and are considered as a threat by industry stakeholders (Martin et al., 2012; DAAF La Réunion, 2020). In addition, many other factors can contribute to lower yields, like climatic conditions and some management practice (Christina et al., 2021). To choose and prioritize weed management practices, it is necessary to analyse the crop-weed interaction at stake within the cropping system, even more in tropical context, where there are very few references and studies on this subject. An agronomic diagnosis using crop modelling may be a useful approach to provide a better understanding of the relative importance of weed competition among the other factors limiting yield (Doré et al., 1997; Affholder et al., 2003). The objective of the study presented here is to analyse the role of weed-crop interactions on yield in sugarcane cropping systems in Reunion Island. To do this, small plots of 25 m2 each were identified to minimize intra-plot variability but maximize inter-plot variability within 25 farmers' fields, spread over the five sugarcane production basins of Réunion Island. The main potential local limiting factors were listed according to a literature review and surveys from local stakeholders (growers, technicians and scientists). Based on this, different variables (climate, cropping practices, weed development, crop growth) will be monitored in all farmers' plots over the sugarcane cropping cycle. We will then use this dataset to estimate the respective weight of the different factors in each cropping situation using crop modelling. The comparison between the simulated potential yield and the observed one should allow us to deduce unexplained difference, which we will attempt to explain by the different variables measured during monitoring. In order to reduce parameter-related errors, the MOSICAS model, parameterized and validated for the sugarcane in Réunion Island, was selected and will be used to simulate potential water-limited yield (Martiné,1996; Christina et al., 2019). If weed-crop competition appears as a major constraint, we will use a functional classification of weed species (Lainé et al., 2023) for an in-depth analysis to determine which species may be the most noxious to sugarcane production. The final aim of this study is to contribute to the understanding of weed-related impacts on sugarcane, and to open a debate on weed control priorities and solutions better suited to each agronomic context.

Mots-clés libres : Crop-weed interaction, Crop model, Yield gap, Sugarcane, Cropping systems

Auteurs et affiliations

• Laine Elise, CIRAD-PERSYST-UPR AIDA (REU)
• Ripoche Aude, CIRAD-PERSYST-UPR AIDA (REU) ORCID: 0000-0001-6756-9777
• Colbach Nathalie, INRAE (FRA)
• Affholder François, CIRAD-PERSYST-UPR AIDA (MOZ) ORCID: 0000-0002-3919-4805

Source : Cirad-Agritrop (https://agritrop.cirad.fr/610409/)

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