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Propriétés physico-chimiques et microbiologiques de substrats organiques utilisés en système hors-sol et suppression de pathogènes

Abstract : Biocontrol used to fight plant pathogens contaminating substrates when growing plants is of considerable concern. This alternative to pesticides is particularly welcome due to the reduced number of authorized fungicides, the increasing number of fungal resistances to fungicides and the pressure from our society to buy products grown in a more sustainable way. Horticulturists and market gardeners are therefore looking forward to new biological strategies to control pathogens. The suppresive effects of some ligno-cellulosic materials marketed by some companies have been already observed. The objective of the present study was to investigate abiotic and biotic factors involved in the suppressive effect of 8 organic substrates: wood fibers, coco fibers and brown peat. To do this, we suspected microbial communities that naturally colonize substrates to play an essential part in this phenomenon. First, biochemical fractions were characterized and compared (Van Soest fractionation analysis, Scanning Electron Microscopy). We also determined the microbial activity (organic substrate mineralization during a 3-month experiment) and analyzed the structure of the microbial communities (PCR-TTGE). Results showed that fungi develop predominantly on substrates. The mineralization kinetic was similar between the two different coco fibers as well as between the four wood fibers. On the contrary, mineralization rates of coco fibers were superior to those of wood fibers. Mineralization dynamic was modeled using first order kinetic and two pool micro-organisms. Biochemical fractions did not explain such differences. However, the structure of the microbial communities (finger-printing by TTGE) was different between substrates. Fungal structures of Peat and coco fibers had 40% similarity. On the contrary the structures of the wood fibers were different and specific. Complementary experiments are ongoing to study relations between organic substrates, the structure of the microbial communities and the suppressive effect against a plant pathogen for cucumber (Fusarium oxysporum f. sp.).
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Contributor : Olivier Dupre <>
Submitted on : Monday, May 11, 2020 - 12:05:45 PM
Last modification on : Monday, July 6, 2020 - 3:38:31 PM

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  • HAL Id : hal-02549741, version 1

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Virginie Montagne, Claire Grosbellet, Hervé Capiaux, Patrice Cannavo, Sylvain Charpentier, et al.. Propriétés physico-chimiques et microbiologiques de substrats organiques utilisés en système hors-sol et suppression de pathogènes. 8èmes Rencontres du Végétal, Agrocampus Ouest - INRA centre Angers-Nantes, Jan 2015, Angers, France. ⟨hal-02549741⟩

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