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Communication Dans Un Congrès Année : 2016

Reduction of Septoria leaf blotch propagation in cultivar mixtures: exploring mechanisms through controlled conditions experimentation and modelling

Résumé

Cultivar mixtures can contribute to a sustainable management of foliar diseases such as septoria leaf blotch. Mixing cultivars differing by their resistance genes makes it possible to partially protect a susceptible cultivar by a resistant cultivar. Architectural properties of the mixture cultivar components can have an impact on their capacity to intercept spores and therefore on disease reduction mechanisms within mixture such as reduction of susceptible host density and barrier of resistant cultivar on spore dispersion. Efficient mixture design is often difficult, given the high number of possible combinations and the complexity of mechanisms involved. Modelling can therefore be a powerful tool to better understand disease reduction mechanisms and identify characteristics of mixtures of interest. However, few models take into account both architecture and resistance heterogeneity of canopies. A modelling approach based on experimental data was used to investigate dispersal mechanisms in mixed canopies with components differing by both their varietal resistance and architecture. A controlled experiment was performed with three types of canopies of 1m2: a mixture of two cultivars and pure stands of these cultivars. A linear inoculum source consisting of an aqueous suspension of spores was disposed in the middle of each canopy and then placed under a rain simulator generator to generate reproducible spore flux. Horizontal and vertical spore fluxes were measured at different points in the canopy using traps composed of microscope slides. Varietal resistance was assessed in parallel. After incubation, disease severity was measured at leaf level on plants sampled from each canopy. Architecture characterization allowed reconstruction of realistic 3D mockups of experimental canopies. A bio-physical model was used to compute splash droplets interception by leaves in 3D canopies. For each leaf of the virtual canopy, lesion area was deduced from the amount of intercepted inoculum and from individual leaf resistance level. Simulated spore fluxes and disease gradients were consistent with experimental measurements. In particular, high leaf area density resulted in higher spore interception by the canopy and higher disease severity. In mixed canopies, resistant plants had higher densities and therefore provided an efficient barrier effect. This modelling approach, now validated on detailed experimental data, can be used to reconstruct dispersal events observed in the field and understand dispersal mechanisms involved in complex canopies such as cultivar mixtures.
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Dates et versions

hal-01531632 , version 1 (01-06-2017)

Identifiants

  • HAL Id : hal-01531632 , version 1
  • PRODINRA : 352347

Citer

Tiphaine Vidal, Pauline Lusley, Marc Leconte, Claude C. Pope de Vallavieille, Laurent Huber, et al.. Reduction of Septoria leaf blotch propagation in cultivar mixtures: exploring mechanisms through controlled conditions experimentation and modelling. 9.International symposium on Septoria diseases of cereals, Apr 2016, Paris, France. p.26. ⟨hal-01531632⟩
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