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Title: EFFECT OF PROPARGYL BROMIDE AND 1,3-DICHLOROPROPENE ON SOIL MICROBIAL COMMUNITIES

Author
item Dungan, Robert - Rob
item Ibekwe, Abasiofiok - Mark
item Yates, Scott

Submitted to: Federation of European Microbiological Societies Microbiology Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/30/2002
Publication Date: 2/1/2003
Citation: DUNGAN, R.S., IBEKWE, A.M., YATES, S.R. EFFECT OF PROPARGYL BROMIDE AND 1,3-DICHLOROPROPENE ON SOIL MICROBIAL COMMUNITIES. 2003. FEDERATION OF EUROPEAN MICROBIOLOGICAL SOCIETIES (FEMS) MICROBIOLOGY ECOLOGY. 43:75-87.

Interpretive Summary: Soil fumigants are widely used in crop production to control soil-borne pathogens. In this study, we investigated the response of the microbial communities in manure-amended and unamended soil treated with either propargyl bromide (PBr) or 1,3-dichloropropene (1,3-D) at a rate of 10, 100, and 500 mg kg-1. Changes in the microbial community were monitored over a 12-week period. The bacterial communities in the fumigated amended soils were dominated by Streptomyces spp., other genera of actinomycetales, and a number of unidentified bacteria. This study demonstrates that the metabolic potential and structure of the microbial communities in fumigated soils will be affected by soil management practices, such as the application of organic manures.

Technical Abstract: In this study, we investigated the response of the microbial communities in manure-amended and unamended soil treated with either propargyl bromide (PBr) or 1,3-dichloropropene (1,3-D) at a rate of 10, 100, and 500 mg kg-1. After treatment of the soils, the metabolic activity was assessed by monitoring dehydrogenase activity (DHA) and substrate-induced respiration (SIR). At PBr and 1,3-D concentrations of 10 and 100 mg kg-1, the DHA and SIR in amended soil was found to be higher than in corresponding unamended soil. Community level changes were monitored over a 12-week period using denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rDNA fragments. Dominant bands all but disappeared upon the application of the fumigants, but reestablished more rapidly in the amended soil. To determine changes in the community diversity, the Shannon-Weaver index of diversity, H, was calculated in each of the fumigated samples. In unamended and amended soil, the community diversity decreased with increasing concentrations of PBr and 1,3-D; however, this effect was less dramatic in the manure amended soils. At 1, 4, 8, and 12 weeks, major bands were excised from the gels and the DNA was cloned for sequence analysis.