Allelochemicals from 'Brassica' SPP. (Canola) Residues: Effects on Other Plants and Cereal Fungal Pathogens

'Brassica' spp. have been reported as showing allelopathic activity against other plants and fungi, with both living material and residues shown to be active. Glucosinolate breakdown products have been implicated in many of these allelopathic effects. Canola is a popular crop in Australia, with evidence of increased crop yields and freedom from fungal root diseases in cereals grown following canola. This supports canola's potential as an inhibitor of pathogens. It was hypothesised that allelopathic activity against other plants and fungi is due to compounds produced from canola residues, notably glucosinolate breakdown products. The experiments reported here supported the hypothesis that glucosinolate breakdown products can be phytotoxic to a number of indicator plant species. Indoleacetylnitrile (IAN), indoleacetylmethanol (IAM) and phenylethylamine (PEA) were shown to inhibit germination and early growth, with IAN being the most active. These compounds were found, using HPLC, to be present in canola residue leachates and their concentration estimated