LINGRA is simple model to calculate grass growth and production under potential and water limited conditions. Simulated key processes are light utilization, leaf formation, leaf elongation, tillering and carbon partitioning to roots and shoots. Source and sink limited growth are simulated independently. Sink-limited growth is characterized by temperature-dependent leaf expansion and tiller development, whereas source-limited growth is determined by photosynthetic light-use efficiency of the canopy and th remobilization of stored carbohydrates in the stubble. At each integration step of 1 day, the available amount of carbon from the source is compared with the carbon required by the sink. The actula growth is determined by the minimum value of either sink or source.