The allelopathic effects of a water extract from Hemistepta lyrata were tested on the seeds of selected crops in Petri dishes. The results showed that the extract strongly inhibited the germination and seedling growth of wheat (Triticum aestivum), rape (Brassica campestris), and radish (Raphanus sativus), but only slightly inhibited those of sorghum (Sorghum vulgare) and cucumber (Cucumis sativus).The extract stimulated the growth of roots and hypocotyls at lower concentrations, while it inhibited their growth at higher concentrations.The malondialdehyde (MDA) content of cucumber and radish increased after treatment with the extract.These results indicated that the MDA concentration in plants is one important aspect of the allelopathic effects of H. lyrata.

This study demonstrated that Trp574Arg substitution was the main reason for crabgrass resistance to ALS-inhibiting herbicides. To our knowledge, this is the first report of Trp574Arg substitution in a weed species, and is the first report of target-site mechanisms of herbicide resistance for crabgrass. © 2017 Society of Chemical Industry.

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