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Weed diversity mitigates crop yield losses: a perspective from European grain-based systems and insights for biodiversity-based weed management

Abstract : Reconciling crop productivity and biodiversity maintenance is one of the main challenges of agriculture worldwide. Weed management is recognized to be a key point for ecological intensification in agriculture because weeds can generate severe yield losses but also represent the base of agricultural trophic networks. Therefore, research in weed science has often opposed two different schools of thought. The drastic decline of biodiversity in agricultural landscapes has either been considered as a sign of efficient weed management or an erosion of the natural capital on which sustainable crop production is founded.Weed: crop competition has historically been studied in experiments, which considered only one weed species at a time. Hence, little is known about the competitive effect of weeds in complex communities (multiple weed species), which is the most frequent scenario in agricultural fields. Nevertheless, major yield losses may simply arise from the dominance of a few competitive species. Moreover, a higher diversity of traits (characteristics) within the weed community could induce complementarity in resource use (light, water, nitrogen) and alleviate weed:crop competition. Therefore, we quantified the effect of naturally occurring weed communities and the diversity of their composition on winter wheat yield, across 54 zones (36 unweeded, 18 weeded) and 3 years. Out of the six weed communities identified, only four generated significant yield losses in unweeded zones, ranging from 19 to 56%. Results show that when community evenness was high, weed biomass was low and weed: crop competition was alleviated. In this case, yield losses are reduced because all weed species produce low biomass. Authors also reveal a positive effect of weed functional diversity on winter wheat yield, even though no relationship with weed biomass was observed. This could hint that a higher diversity of traits within the weed community limits competition with the crop and hence, yield losses.Weeding operations should exclusively target competitive and dominant species. However, current weed control practices do not allow targeting a specific species in a complex community. Therefore, future studies need to identify if weed diversity could rather be indirectly promoted by diversifying weed management tools . In addition, a diversity of farming practices in time may lead to increase the diversity of resources pool and thus should decrease the crop: weed competition. The CA-SYS platform represents one of the major tools in Europe to experiment these hypotheses since the overarching objective of the CA-SYS platform (https://www6.inra.fr/plateforme-casys_eng/) is to design and test the feasibility and performances of pesticide-free agriculture using (cropped and wild) biodiversity in support of production, i.e. biodiversity-based forms of agriculture.
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https://hal.inrae.fr/hal-02945472
Contributor : Noureddine El Mjiyad <>
Submitted on : Tuesday, September 22, 2020 - 12:36:58 PM
Last modification on : Wednesday, October 14, 2020 - 4:13:14 AM

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  • HAL Id : hal-02945472, version 1

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Stéphane Cordeau. Weed diversity mitigates crop yield losses: a perspective from European grain-based systems and insights for biodiversity-based weed management. Biennial Conference of Indian Society of Weed Science: Weed Management for Enhancing Farmer income and Food Security (Proceedings of ISWS Indian Society of Weed Science), Feb 2020, Goa, India. pp.3. ⟨hal-02945472⟩

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