Weed diversity reduced by the dominance of barley and pea monocultures and mixtures

POGGIO, S. L.

Durban, Sudáfrica

Congreso; 4th International Weed Science Congress; 2004

International Weed Science Society

Intercropping, the cultivation of two or more crops in the same land area, is an alternative to diversify agro-ecosystems that may help solving some negative effects of modern agriculture. Weed suppression is an advantage of intercropping that may contribute to reduce herbicide application in agriculture. To study the effect of intercropping on weed communities, field experiments were carried out at Buenos Aires and Rojas (Argentina) involving monocultures and mixtures of barley and pea, and a control treatment in which weeds grew in the absence of crops. Effects on weed communities were characterised in terms of growth, species diversity (richness and equitability), rank-abundance plots, and plant functional traits. Plant nitrogen and interception of solar radiation were also measured. Mixtures and barley strongly dominated over weeds, suppressing growth and reducing the community diversity. Those treatments reduced both nitrogen in weed biomass and radiation reaching weed leaves. On average, species richness was reduced almost a 50% by mixtures and barley. Pea effects on weed communities were less suppressive and more variable. Winter annuals were mainly suppressed by crop treatments, while spring annuals were less abundant in the unsown control. Divergence in the abundance of winter and summer emerging weeds could be attributed to the different canopy dynamic of crop treatments, which would have differently modified the environment experienced by weeds (e.g. light quality, temperature). This work contributes to improve our understanding of plant succession in agro ecosystems and may help in developing low-input practices for weed management.