Author
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Kremer, Robert |
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Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only Publication Acceptance Date: 2/3/1997 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Microbial communities associated with plant roots generally possess a component of non-parasitic bacteria able to inhibit or reduce plant growth. These deleterious rhizobacteria (DRB) likely inhibit plant growth through production of substances that interfere with root physiological processes. Growth inhibition can be caused by high concentrations of auxins, low molecular weight metabolites, and hydrogen cyanide. Approximately 15% of a collection of DRB from Euphorbia spp. produced high levels of hydrogen cyanide (HCN) based on qualitative analyses. Using quantitative analysis, DRB produced HCN ranging from 5 to 75 umoles in agar culture. Different weed seedlings responded differently when challenged with HCN-producing DRB. Root length inhibition ranged from 30% for green foxtail (Setaria viridis) to 63% for barnyard grass (Echinochloa crus-galli). Concentrations of 10 to 60 umoles HCN exogenously applied to seedlings significantly reduced root growth of all weed species tested indicating similar levels produced by DRB are within a range causing phytotoxicity. Similar phytotoxicity occurred with dose-response assays of quinclorac, which induces HCN accumulation in plants. DRB established in weed seedling rhizospheres may cause phytotoxicity partly due to excessive production of HCN, a mode of action similar to some herbicides including quinclorac. |
