The relevance of morphological plasticity in the simulation of competitionbetween maize and Datura stramonium

The INTERCOM model was calibrated for Datura stramonium and maize with data from monoculture plots, and used to simulate the competition between the w eed and the crop. The model adequately simulated the growth (leaf area inde x, above-ground biomass, plant height, yield) of both species in monocultur e. In competition, the growth of D. stramonium and the competitive effect o f D. stramonium on the growth of maize were clearly underestimated. Simulat ion of competition was improved when the observed morphological adaptations of D. stramonium under competitive light stress, as reflected in dry-matte r partitioning, height growth and specific leaf area (SLA) were considered. Model analysis demonstrated that the observed changes in SLA and height gr owth were more relevant for the increased competitive ability of D. stramon ium. The modification of the model in order to simulate the effect of shadi ng by an overtopping species in the SLA of the shaded species improved mode l simulation of competition.