Annals of Biological Research
Abstract
Author(s): Shima Alipour1, Ezatollah Farshadfar*2, Mohammad Amirian3 and Mansoor Montazeri4
The allelochemicals or secondary plant metabolites when are released to environment, influence the germination
and seedling growth of neighbors' weeds. The aim of this study was to investigate the effect of the extract of St
Johnson wort (Hypericum perforatum) on the number and mass of weed seedlings and their seed germination under
laboratory conditions. The St Johnson wort extracts were considered with different concentrations (1.25 to 20%) 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
increasing concentration of St Johnson wort 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 Johnsongrass, corn seed germination and length of plumules were attributed to the
osmotic pressure of the extract, where, inhibition of seed germination of Redroot pigweed and Common
lambsquarter was due to allelochemicals.
