Modelling the competition for light and nitrogen between rice and Echinochloa crus-galli.
A model was developed to simulate the growth and development of rice and E. crus-galli. Competition for light was related to plant height and vertical leaf area distribution, while competition for N depended on root mass. The model, originally developed for rice, was validated for E. crus-galli at different planting densities. Predictions on biomass growth of competing rice and E. crus-galli were compared to field data collected in a replacement experiment. The effect of E. crus-galli competition on rice yield was shown for various crop and weed planting densities.