Le rôle de l'allélopathie dans la régulation des adventices : entre rêve et réalité.

To what extent can allelopathy contribute to regulate weeds in the field? This controversial question is of major interest in agroecology. Quantifying the effects of this mechanism, however, presents a difficulty: dissociating the effects of allelopathy from those of other mechanisms, such as competition for resources. Here, a systematic review of the scientific literature was conducted to identify field-based evidence of the role of allelopathy (by living crops only) in weed regulation, independently of competition (focusing on studies comparing different crop varieties of the same species). We show that, in most articles, the role of competition is not considered or studied exhaustively. Thus, contrary to the authors' conclusions, it is not possible to determine whether weed regulation is due to allelopathy or competition. Overall, few studies provide convincing evidence of the effects of allelopathy in the field.