Phytotoxins from plant residues

Staman et al. (2001) stated that in order to demonstrate that allelopathic interactions are occurring, one must, among other things, demonstrate that putative phytotoxins move from plant residues on or in the soil, the source, through the bulk soil to the root surface, a sink, by way of the rhizosphere. These authors hypothesized that the incorporation of phytotoxic plant residues into the soil would result in a simultaneous inhibition of seedling growth and a stimulation of the rhizosphere bacterial community that could utilize the putative phytotoxins as a carbon source. If true and consistently expressed, such a relationship would provide a means of establishing the transfer of phytotoxins from residue in the soil to the rhizosphere of a sensitive species under field conditions, presently, direct evidence for such transfer... 

Staman, K, Blum, U., Louws, F., Robertson, D. Can simultaneous inhibition of seedling growth and stimulation of rhizosphere bacterial populations provide evidence for phytotoxin transfer from plant residues in the bulk soil to the rhizosphere of sensitive species J Chem Ecol 2001 27 807-829. 

Phytotoxins synthesized in the rhizosphere by microorganisms may play a greater role in plant growth than those derived from the breakdown of crop residues. This is chiefly because the rhizosphere flora feeds on a continuous supply of exuded food that is especially suitable for antibiotic-producing microorganisms. The antibiotics produced ... 

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