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ARS Home » Pacific West Area » Pullman, Washington » Northwest Sustainable Agroecosystems Research » Research » Publications at this Location » Publication #162506
Title: EFFECT OF TILLAGE, FUNGICIDE SEED TREATMENT, AND SOIL FUMIGATION ON SEED BANK DYNAMICS OF AVENA FATUA

Author
item GALLANDT, ERIC - UNIVERSITY OF MAINE
item FUERST, E - WASHINGTON STATE UNIVERSI
item Kennedy, Ann

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2004
Publication Date: 5/1/2004
Citation: Gallandt, E.R., Fuerst, E.P., Kennedy, A. C. 2004. Effect of tillage, fungicide seed treatment, and soil fumigation on seed bank dynamics of wild oat (Avena fatua). Weed Science 52:597-604.

Interpretive Summary: Background In the Pacific Northwest, no-tillage offers potential for improved soil quality, reduced erosion, and equal or increased crop yields. In no-tillage systems seeds remain at or near the soil surface where crop residues, moisture, and lack of disturbance create an environment with greater soil microbial diversity. Description To better understand microorganisms and weed seed decay, we evaluated the effects of tillage, soil fumigation, and fungicides on the decay of wild oat. The effect of tillage on wild oat seed death was not consistent over the two years of our study. The proportion of dead seed was generally similar in no-till and conservation tillage systems. The contribution of microorganisms to seed fate is similar in these tillage environments. More than half of the wild oat seed bank losses could be directly attributed to germination whereas losses due to decay were relatively minor by comparison. We conclude that a greater variety of soil environments and weed species needs to be studied. Efficient assays of seed quality and seed decay would permit evaluation of a diversity of weed species under a wider range of soil environments. Correlation of microbial community and soil quality characteristics with weed seed deterioration is needed to study the impact of soil quality may have on the persistence of the weed seed bank. (Impact) This research on weed seed decay will allow scientists to better understand and perhaps more fully exploit the relationships between soil microorganisms and weed seed decay and lead to the development of more ecologically based weed management systems.

Technical Abstract: In the Pacific Northwest, no-tillage offers potential for improved soil quality, reduced erosion, and equal or increased crop yields. In no-tillage systems seeds remain at or near the soil surface where crop residues, moisture, and lack of disturbance create an environment with greater soil microbial diversity. In late fall of 1998 and 1999, dormant seed of wild oat, either individually glued to plastic toothpicks or mixed with soil and placed in mesh bags, were buried (mean seed depth of 2.5 cm) in replicated field plots managed by no-tillage or conservation tillage (chisel/disk) since 1982. Treatments including fungicide seed treatment (thiram + metalaxyl + captan) and soil fumigation (propylene oxide) were performed to alter seed and soil microbial communities thereby providing estimates of the contribution of microorganisms to observed mortality. Tillage system effects on wild oat seed mortality were not consistent over the two years of our study. The proportion of dead seed was generally similar in no-till and conservation tillage systems. Lack of tillage system by seed or soil treatments effects on the proportion of dead or decayed seed suggests that the contribution of microorganisms to seed fate is similar in these tillage environments. However, the proportion of dormant seeds was consistently lower in the no-till compared to conservation tillage treatments; there was a corresponding increase in the proportion of germinated seeds. Overall, more than half of the wild oat seed bank losses could be directly attributed to germination whereas losses due to decay were relatively minor by comparison.