Interactions between allelochemicals and the microbial community affect weed suppression following cover crop residue incorporation into soil

Research output: Contribution to journalArticlepeer-review

Abstract

Background and aims: The objective of this study is to understand how soil microorganisms interact with cover crop-derived allelochemicals to suppress weed germination and growth following cover crop residue incorporation. Methods: We conducted a time series experiment crossing sterilized and non-sterilized soil with four different residue treatments. We measured weed seed germination rates, radicle elongation, and disease incidence in seed germination bioassays. We also monitored cover crop-derived, isoflavone allelochemicals in these bioassays. We partitioned the total weed suppression into three sources: microbe-only inhibition, residue-only inhibition, and the microbe-residue interaction. Results: Microbial activity suppressed weed germination and growth for 30 days, while cover crop-derived allelochemicals provided suppression for a limited time. There was an antagonistic interaction between microbes and allelochemicals. This interaction was strongest for water-soluble allelochemicals, while residue fractions containing intact plant tissues retained greater suppressiveness even in the presence of a live microbial community. Conclusions: Microbial activity can directly suppress weed germination and growth, but microorganisms also indirectly help weeds by degrading cover crop-derived allelochemicals. As a result of these interactions, cover crop-derived weed suppression in agricultural soils shifts from an early allelochemical-dominated phase to a later phase where microbial suppression is more important.

Original languageEnglish (US)
Pages (from-to)357-371
Number of pages15
JournalPlant and Soil
Volume399
Issue number1-2
DOIs
StatePublished - Feb 1 2016

Keywords

  • Allelochemicals
  • Isoflavones
  • Red clover (Trifolium pratense L.)
  • Soil microbes
  • Weed suppression
  • Wild mustard (Sinapis alba L.)

ASJC Scopus subject areas

  • Soil Science
  • Plant Science

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