A SIMULATION-MODEL OF COMPETITION BETWEEN WINTER-WHEAT AND AVENA-FATUA FOR LIGHT

An eco-physiological simulation model of competition between Avena fatua and winter wheat (Triticum aestivum cv. Avalon) for light was parameterised and tested. The model simulates growth of each species, in kg dry matter ha-1 day-1, from sowing to maturity as a function of irradiance. temperature and various species characteristics. Parameter values were derived from the literature and from field experiments with each species grown in monoculture. Model performance was tested against 50:50 mixtures of the two species grown at two sites in southern England. Sensitivity analyses were performed in which the canopy height of each species and the density and time of emergence of A. fatua were systematically varied while all other parameters were left unchanged. Accurate simulations of growth in mixtures depended upon an accurate description of the canopy height of each species throughout the growing season. Model predictions of winter wheat yield losses in relation to A. fatua density and time of emergence showed good agreement with previously published data.