Author
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LI, JIANMEI - UNIV OF MO |
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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: 2/10/1999 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: The use of deleterious rhizobacteria (DRB) for suppressing growth of seedling weeds is one approach being evaluated as a component of biological weed management systems. Little information is available on the environmental conditions that affect the occurrence and activity of DRB that occur naturally in soils. Our objective was to determine the influence of various crop management systems on the selection of and activity of DRB toward weed seedlings. Seedlings of the dominant weed species in six difference agroecosystems were collected in spring 1997. Root-associated bacteria were cultured from the seedlings and bioassayed for phytotoxicity to lettuce seedlings (indicator species) and to their host weed seedlings. The root-colonizing ability of selected DRB on weed seedlings was documented using scanning electron microscopy. The type of cropping system appeared to affect the frequency of DRB occurrences. An integrated cropping system consisting of a no-till wheat-corn-soybean rotation with reduced application rates of herbicides had weed seedlings with the highest frequency of DRB. High soil organic matter contents in soils from an organic farming system and an uncultivated prairie appeared to promote colonization of weed seedling roots compared to other soils with lower organic matter. Understanding the effects of different agroecosystems on naturally-occurring DRB could lead to the development of biologically-based methods to promote these organisms for nonchemical weed management. |
