Functional–structural plant modelling in crop production. Wageningen UR Frontis Series, vol. 22

The first three-dimensional (3D) computer models of plant structure were developed in the 1980s, and amazing, ‘faithful to botany’ images could be produced with these models. As no plant functional processes were embedded in the models, their applications in agronomy and horticulture were limited. To overcome this drawback, great efforts have been made from the mid-1990s onwards by researchers throughout the world to develop functional–structural plant models (FSPMs) through combining plant functional processes at organ level with explicit descriptions of their topological and geometric structure (for example, see Fourcaud et al., 2008). FSPMs involve a variety of disciplines including botany, biology, ecology, mathematics and information technology, and hence it is difficult for researchers beginning in FSPMs to handle such complexity. Therefore, a book that brings together a wide range of aspects of FSPMs is very timely. The book consists of 22 chapters, including overviews of the basic concepts of FSPMs, major tools for developing FSPMs, modelling examples for specific crops, and their applications. One striking aspect of this book is that many noted researchers in the field of FSPMs have made contributions to it. The first chapter gives a short account of plant modelling, and describes the basic concepts and steps of functional and structural modelling. This is followed by a chapter on experimentation for FSPM. While the term ‘virtual plants’ is usually used as a synonym for FSPMs, it is not expected to create a virtual world separated from the real one. This chapter outlines the measurements needed for calibration and validation of FSPMs, including 3D digitizing for spatial data capture. The next four chapters focus on major methodologies to program FSPMs, including: the famous software, L-Studio; a programming language, XL, that has been developed as an extension of the L-system and the related modelling platform, GroIMP; the improved version of the VICA model, which formulates plant development as a set of hierarchically structured objects; and the GREENLAB model, which was derived from the extremely powerful architectural model AMAP, and is described here with a successful calibration example for maize. FSPMs are specially suitable for analysing problems in which the plant structure plays a key role, for example it is a very powerful tool for light-distribution simulation in 3D plant canopies. In Chapter 7, approaches for modelling the spatial light environment of crop canopies are described, including some classic and fast methods as well as some extremely complicated approaches. A mechanistic model of barley is presented in Chapter 8, where a local gas and radiant-energy exchange model is combined and the effect of organ nitrogen content on photosynthesis is accounted for. As carbon partitioning among plant organs is the weak point of most plant models, special attention is given to carbon partitioning modelling in this book. In Chapter 9, five approaches for modelling carbon partitioning are described concisely in order of their complexity – descriptive allometry, functional equilibrium, canonical modelling, sink regulation and transport resistance – and their pros and cons are discussed. In the following chapter, a mechanistic model of carbon partitioning based on the concept of transport resistance is presented. This is followed by two chapters on simulation of the structural growth of peach trees based on a transport resistance model. As such mechanistic models can be quite difficult and expensive to build, in Chapter 13 a simpler approach is introduced for modelling plant functions at an intermediate level of complexity. As the ‘hidden half’ of a plant, the roots play a key role in plant water and nutrient uptake. While root modelling per se is not addressed in this book, an integrated functional–structural model is presented in the following chapter to simulate the structural dynamics of maize shoots and roots simultaneously based on the sink regulation concept. Because of their importance in agronomy and horticulture, quite a number of models for the Gramineae have been developed using the FSPM approach. The basic concepts for modelling the topological and geometric structure of Gramineae is described in Chapter 15, and is followed in the next three chapters by some other modelling examples for specific crops: faba bean, chrysanthemum and greenhouse-grown cucumber. This book also describes some interesting applications of FSPMs in a broader context. Its value in the field of remote-sensing research is discussed in Chapter 19, and the potential applications of FSPMs in analysing crop–weed interactions in arable plant communities are described in Chapter 20. FSPMs are expected to be valuable tools for analysing the effects of variation in genetic properties on plant development and in Chapter 21 a developmental model of barley is built by incorporation of some genetic and physiological processes. The potential application of this model in crop breeding is briefly discussed. The book ends with a chapter that describes the application of structural models in understanding insect prey–predator relations, as FSPMs can provide a realistic opportunity for modelling the behavior of predators and pests in crop canopies. Overall, this is an excellent book on an exciting topic, and it is well written by experts in the various fields. While a variety of topics are presented quite briefly in the book, the references cited provide a comprehensive resource of papers and reviews to enable readers to seek out further details. I highly recommend this book for undergraduates, graduate students and scientists interested in updated approaches in plant modelling.