Functional-structural modelling of faba bean

Crop models such as CERES and CropSyst treat canopies as homogeneous entities without attempting to define canopy geometry, other than through row structure, nor deal with growth processes at time steps shorter than one day. A functional-structural modelling approach can improve canopy simulation, in particular of indeterminate crops such as faba bean. A major challenge is to incorporate the plasticity of the canopy. Functional-structural models can accomplish this by introducing variation in several ways and at different levels of canopy composition. ALAMEDA is a functional-structural model of a faba bean (Vicia,faba L.) crop that addresses these issues. An L-system provides the basic conceptual and program structure within which functional relationships can be connected. In this way it plays a comparable role to physical plant structure that provides the linkage between morphology and physiological processes spatially distributed over plant components. In accordance with results of previous studies with faba bean, the stem was selected as the main building module. An associated growth model is linked to calculate the lengths of the vegetative organs, and leaf allometries are used to compute leaf area. ALAMEDA is currently being extended by including a model of radiation interception and functions from classic models, for example, the variation of specific leaf area with temperature as specified in CROPGRO-legume.