Journal Article

Modelling the effect of wheat canopy architecture as affected by sowing density on <i>Septoria tritici</i> epidemics using a coupled epidemic–virtual plant model

Rim Baccar, Christian Fournier, Tino Dornbusch, Bruno Andrieu, David Gouache and Corinne Robert

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 108, issue 6, pages 1179-1194
Published in print October 2011 | ISSN: 0305-7364
Published online July 2011 | e-ISSN: 1095-8290 | DOI: https://dx.doi.org/10.1093/aob/mcr126
Modelling the effect of wheat canopy architecture as affected by sowing density on Septoria tritici epidemics using a coupled epidemic–virtual plant model

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

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Background and Aims

The relationship between Septoria tritici, a splash-dispersed disease, and its host is complex because of the interactions between the dynamic plant architecture and the vertical progress of the disease. The aim of this study was to test the capacity of a coupled virtual wheat–Septoria tritici epidemic model (Septo3D) to simulate disease progress on the different leaf layers for contrasted sowing density treatments.

Methods

A field experiment was performed with winter wheat ‘Soissons’ grown at three contrasted densities. Plant architecture was characterized to parameterize the wheat model, and disease dynamic was monitored to compare with simulations. Three simulation scenarios, differing in the degree of detail with which plant variability of development was represented, were defined.

Key Results

Despite architectural differences between density treatments, few differences were found in disease progress; only the lower-density treatment resulted in a slightly higher rate of lesion development. Model predictions were consistent with field measurements but did not reproduce the higher rate of lesion progress in the low density. The canopy reconstruction scenario in which inter-plant variability was taken into account yielded the best agreement between measured and simulated epidemics. Simulations performed with the canopy represented by a population of the same average plant deviated strongly from the observations.

Conclusions

It was possible to compare the predicted and measured epidemics on detailed variables, supporting the hypothesis that the approach is able to provide new insights into the processes and plant traits that contribute to the epidemics. On the other hand, the complex and dynamic responses to sowing density made it difficult to test the model precisely and to disentangle the various aspects involved. This could be overcome by comparing more contrasted and/or simpler canopy architectures such as those resulting from quasi-isogenic lines differing by single architectural traits.

Keywords: Crop architecture; modelling; Septoria tritici; wheat; Triticum aestivum; sowing density; 3-D virtual plant model; plant–pathogen interaction

Journal Article.  11350 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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