INRA, UMR 1091 EGC, F-78850 Thiverval-Grignon, France.
Ann Bot. 2011 Oct;108(6):1179-94. doi: 10.1093/aob/mcr126. Epub 2011 Jul 1.
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.
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.
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.
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.
由于动态植物结构和疾病垂直进展之间的相互作用，飞溅传播疾病——叶斑病和其宿主之间的关系很复杂。本研究的目的是测试耦合的虚拟小麦-叶斑病流行模型（Septo3D）模拟不同播种密度处理下不同叶层病害进展的能力。
在三个对照播种密度下进行了冬小麦“索松”的田间试验。对植物结构进行了特征化处理，以对小麦模型进行参数化，并对疾病动态进行了监测，以与模拟结果进行比较。定义了三个模拟场景，它们在表示植物发育变异性的详细程度上有所不同。
尽管密度处理之间存在结构差异，但疾病进展差异很小；只有低密度处理导致病变发展速度略高。模型预测与田间测量结果一致，但无法再现低密度下病变进展速度更快的情况。考虑到植物间变异性的冠层重建情景产生了与测量和模拟流行情况之间的最佳一致性。使用相同平均植物群体代表冠层进行的模拟与观察结果偏差很大。
可以对详细变量进行预测和测量的流行情况进行比较，这支持了该方法能够提供对有助于流行情况的过程和植物特征的新见解的假设。另一方面，对播种密度的复杂和动态响应使得很难精确测试模型并区分所涉及的各个方面。通过比较更具对比性和/或更简单的冠层结构（例如由单个结构特征差异的准同基因系产生的结构）可以克服这一问题。
