A Model Allocating Growth Among Leaf Proteins, Shoot Structure, and Root Biomass to Produce Balanced Activity

A model is developed that considers the allocation of carbonand nitrogen substrates to a protein compartment in the shoots,shoot structural components, and root biomass. Inclusion ofa shoot-protein compartment allows variation in shoot-specificactivity to be modelled as a function of leaf nitrogen concentration.Allocation to the biomass compartments is controlled by twopartitioning variables that are defined by explicitly usingthe balanced activity hypothesis. The model produces balancedactivity where the shoot-specific activity, as well as rootand shoot biomass, vary in response to the above-ground (lightand CO₂) and below-ground (nitrogen) environments. The predictedpatterns of both root: shoot ratio and leaf nitrogen concentrationin response to environmental resource availability are qualitativelyconsistent with general trends observed in plants. Biomass allocation, plant growth, modelling, leaf nitrogen, root: shoot ratio, balanced activity