, Volume 292, Issue 1-2, pp 95-103
Date: 14 Feb 2007

Modelling the combined effect of chemical interference and resource competition on the individual growth of two herbaceous populations

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Resource competition and chemical interference are mechanisms of interaction among plants that may occur simultaneously. However, both mechanisms are rarely considered together when modelling plant growth. We propose a new empirical model that estimates biologically significant parameters on both plant competition and chemical interference. The model is tested with data sets from different density-dependent experiments done with two species (the grass Lolium rigidum Gaud. and the legume Glycine max soya L.) subjected to a noxious chemical environment when growing (allelochemicals and herbicides, respectively). Hypotheses on the effect of allelochemicals and its interaction with density are tested using maximum likelihood ratio tests in order to ask, for these species, whether chemical interference is playing a significant role in the interactions among plants or on the contrary, whether interactions among plants are sufficiently explained by the resource competition. In all cases a significant interaction between chemicals and density is observed. This interaction is inconsistent with the hypothesis of only resource competition having an influence of plant biomass and suggests a significant density-dependent effect of chemicals on plant growth.