Main theme: Plant Form and Function
The common denominator in all projects within the plant form and function (PFF) theme is plant growth and development as shaped by the feedback between environmental and physiological factors in specific ecological settings. Currently, by far the most dominant environmental factor taken into account is light, both as a driver of photosynthesis and therefore as a resource for which plants compete, but also as a driver of photomorphogenesis and therefore as a signal that plants respond to. Physiological processes that are taken into account include photosynthesis and carbon distribution, apical dominance, photomorphogenesis, shade avoidance, and nutrient uptake and distribution. Finally, the most dominant ecological setting is the crop canopy, in which plants of the same or different species compete with and respond to each other.
The research questions that are addressed in PFF projects are all related to plant performance, i.e. how has selection – either natural or by humans – acted on the regulation of plant form and function in its response to the environment. A key aspect of plant development related to performance is developmental plasticity: how do plants adapt their development in response to environmental variables (light quantity and quality, soil water and nutrients, insect herbivory, temperature) and how are these cues shaped by other plants (shading, light scattering, uptake of water and nutrients from the soil) in pure or mixed plant stands. There appears to be a host of different links between plant performance and form-function relationships of plants in crop and natural settings. The PFF line of research aims at elucidating the underlying processes, understanding the consequences for plant and crop performance, and use this knowledge to aid the development of better functioning crops.
The main tools that are used to address question regarding crop form and function are functional-structural plant (FSP) modelling closely linked with dedicated field, glasshouse or growth-chamber experiments. The essence of FSP models is the simulation of the relationship between plant functioning and plant structure in 3D, with explicit feedback between plant growth and development on the one hand and environmental drivers on the other. This feedback is crucial to the functionality of FSP models: for instance, light capture by leaves determines the production of growth substrates and eventual growth of leaves, stems and other plant organs resulting in a change in plant structure, but this change itself determines to what extent light can be captured. Here, the 3D aspect of FSP models plays an important role, since growth of organs like leaves and stems may result in different (self) shading patterns depending on their positioning in 3D space, affecting light interception and ultimately growth. The same is true for other resources such as water or nitrogen distribution in the soil in relation to root system architecture. This feedback makes FSP models appropriate tools to simulate crop vegetation performance emergent from the underlying processes related to interaction between plants.