A comparison of the growth patterns and the competitive ability of four annual weeds

Abstract

The competitive effects and responses of four annual weeds (Avena sterilis, Bromus diandrus, Galium tricornutum and Veronica hederifolia) were compared under greenhouse and field conditions.The two grasses had similar competitive effects that were much greater than the effects of the two dicotyledoneous weeds.In all the experiments, A. fatua was the most competitive species and V. hederifolia was the least competitive.In terms of response, A. sterilis demonstrated the highest tolerance to competition, followed by B. diandrus, V. hederifolia and G. tricornutum.The correlations between the rankings of competitive effect and response were generally poor: the species that cause larger reductions in growth of their neighbours are not always the least affected by the presence of competitors.The observed competitive hierarchies were not consistently associated with early season weed parameters.The only plant trait that presents a certain correlation with competitive effect is seed weight.However, the response to competition seems to be well correlated with biomass and leaf area in the early stages of growth. Competitive ability /Avena sterilis / Bromus diandrus / Galium tricornutum / Veronica hederifolia Résumé -Comparaison du développement et de la capacité de concurrence de quatre adventices annuelles.Quatre adventices annuelles (Avena sterilis, Bromus diandrus, Galium tricornutum et Veronica hederifolia) ont été comparées du point de vue des effets de et des réponses à la concurrence entre elles, en conditions de serre et en plein air.Les deux graminées ont eu les mêmes effets de concurrence, toujours supérieurs à ceux dus aux deux dicotylédones.Dans toutes les expériences, A. fatua a été l'espèce la plus compétitive et V. hederifolia la moins compétitive.En termes de réaction, A. sterilis a montré la tolérance la plus grande à la concurrence, suivie de B. diandrus, V. hederifolia et G. tricornutum.