Allelopathic effects of Yarrow (Achilla millefalium) on the weeds of corn(Zeamays L.)

The allelochemicals or secondary plant metabolites when released to the environment, influence the germination and seedling growth of neighbor weeds. The aim of this study was to investigate the effect of the extract of Yarrow (Achilla millefalium) on the number and mass of weed seedlings and their seed germination under laboratory conditions. The effects of different concentrations (1.25 to 20%) of Yarrow extracts were evaluated on the germination and seedlings growth of Zea maize, Johnsongrass (Sorghum halepense), Common lambsquarter (Chenopodium album) and Redroot pigweed (Amaranthus retroflexus) for 5 days. Results showed that with the increasing concentration of Yarrow extracts, their effects on reducing seed germination and seedling growth of the above mentioned plants were more severe. Comparison of extract effects with polyethylene glycol, revealed that reduction of seed germination and seedling growth in Johnsongrass and Common lambsquarter were attributed to the osmotic pressure of the extract, whereas inhibition of seed germination of Redroot pigweed and corn was due to allelochemicals