Descriptive and mechanistic models of crop–weed competition

Crop-weed competitive relations are an important element of agroecosystems. Quantifying and understanding them helps to design appropriate weed management at operational, tactical and strategic level. This chapter presents and discusses simple descriptive and more mechanistic models for crop-weed interaction. Along with an elaboration of underlying principles, attention is on application of the models in support of research, management and policy development. The main purpose of mechanistic crop-weed competition models is to obtain a better quantitative understanding of crop-weed interactions and to identify how species characteristics, management interventions and environmental factors such as resource availability and climate change influence the competitive relations between crop and weed. The use of mechanistic models for crop-weed competition not only allows the ranking of genotypes on weed-suppressive ability, but also allows identification of appropriate traits capable of increasing weed suppressiveness without penalising yielding ability in the absence of weeds.