Towards a quantitative description of the impact of local light environment on morphological plasticity in cereal crops using functional structural plant models

一般来说，植物的形态可塑性，特别是同化叶的形态可塑性，强烈地受到可利用光的数量和质量的影响。植物生态学家称这种行为为阳光与阴影叶二分法。我的博士后工作的目的是研究谷物叶片作为最重要的同化器官，在何种程度上适应光环境，以及是否可以发现吸收的光的量与叶片的形态和生理性状之间的定量关系。为此，提出了功能结构植物模型（FSPM）的应用。这里建议的建模方法结合了基于计算机的重建的谷物冠层和计算的光吸收与辐射传输模型的单个叶片。通过2007-2009年冬小麦（Triticum aestivum L.）CV. Soisson），研究了播期和密度对植株形态的影响。使用这些数据，使用模型阿德尔小麦重建小麦的3D结构。通过比较地面覆盖和叶面积指数的模拟数据和实测数据进行模型验证。使用这种方式计算的“虚拟小麦冠层”，将计算叶片吸收的光的量，并将其与在相应叶片上测量的方向、宽度和比质量相关联。所研究的基因型-环境组合的潜在关系将用数学函数来描述。这些定量关系适用于FSPM对植物光觅食行为及其后果的模拟的3D形态，这最后有助于提高理解的形态适应植物（叶），特别是他们的光环境和谷物可塑性的机制一般。这将最终导致更好地了解谷物生产中的技术选择，这里是播种密度或日期，如何影响作物形态和特定环境条件下的可收获产量。

The morphological plasticity of plants in general, and of assimilating leaves in particular, is strongly influenced by the amount and quality of available light. Plant ecologists call this behavior sun vs. shade leaf dichotomy. The aim of my post-doctoral work is to investigate to which extent cereal leaves, as most important assimilating organs, adapt to the light environment, and whether quantitative relationships between the amount of absorbed light and morphological and physiological leaf traits can be discovered. To do this, the application of a Functional-Structural Plant Model (FSPM) is proposed. The modeling approach suggested here combines the computer-based reconstruction of a cereal canopy and the computation of light absorption by individual leaves with a radiation transfer model. Morphological data is obtained from a two-season field trial (2007-2009) on winter wheat (Triticum aestivum L. cv. Soisson), where effects of sowing date and density on plant morphology are investigated. Using this data the 3D architecture of wheat is reconstructed using the model ADEL wheat. Model validation is performed by comparing modeled and measured data of ground cover and leaf area index. Using the ‘virtual wheat canopies’ calculated this way amount of absorbed light by leaves will be calculated and related to orientation, width and specific mass measured on the respective leaf. Potential relationships for the investigated genotype - environment combinations will be described with mathematical functions. These quantitative relationships are applicable in FSPMs towards a simulation of plants light foraging behavior and its consequences for the 3D morphology, which lastly contributes to an improved comprehension of the morphological adaptation of plants (leaves) to their light environment in particular and to mechanisms of cereal plasticity in general. This will finally lead to a better understanding of how technical choices in cereal production, here sowing density or date, affect crop morphology and harvestable yield under particular environmental conditions.