This section presents an overview of plant physiology concepts involved in crop modelling.

Thermal Time normalization - The thermal time normalization allows comparing plant growth on both organogenesis (organ numbering) and development (organ size) aspects.

Light interception: PAR, LAI and Beer-Lambert Law - Only part of the light energy is used in plant crops. A limited fraction of the light spectrum is absorbed by the leaves; this part is constrained by the upper leaf area and decreases in the canopy.

Photosynthesis. Light Use Efficiency - Photosynthesis process converts absorbed light energy to biomass with a ratio proportional to the Light Use Efficiency.

Density effect - At the individual plant level, density limits light absorption capabilities, and thus dynamically limits the biomass production.

Biomass common pool - Biomass produced by the source Organs (leaves) builds a common storage pool, to be share among all competing growing organs.

Organ competition - Sinks Organs growing compete for biomass allocation. They are sinks.

Process Bases Models - Process Based Models or Crop models aim to model and simulate the biomass production.