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Pea (Pisum sativum) seed production as an assay for reproductive effects due to herbicides

Authors

  • David Olszyk,

    Corresponding author
    1. U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Western Ecology Division, 200 SW 35th Street, Corvallis, Oregon 97333
    • U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Western Ecology Division, 200 SW 35th Street, Corvallis, Oregon 97333
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  • Thomas Pfleeger,

    1. U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Western Ecology Division, 200 SW 35th Street, Corvallis, Oregon 97333
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  • E. Henry Lee,

    1. U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Western Ecology Division, 200 SW 35th Street, Corvallis, Oregon 97333
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  • Milton Plocher

    1. Dynamac Corporation, 200 SW 35th Street, Corvallis, Oregon 97333, USA
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  • This document has been subjected to review by the National Health and Environmental Effects Research Laboratory's Western Ecology Division and approved for publication. Approval does not signify that the contents reflect the views of the U.S. Environmental Protection Agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use.

Abstract

Even though herbicide drift can affect plant reproduction, current plant testing protocols emphasize effects on vegetative growth. In this study, we determined whether a short-growing season plant can indicate potential effects of herbicides on seed production. Pea (Pisum sativum cv. Dakota) plants were grown in mineral soil in pots under greenhouse conditions. Plants were treated with a variety of herbicides (dicamba, clopyralid, glufosinate, glyphosate, 2-methyl-4-chlorophenoxyacetic acid, primisulfuron, or sulfometuron) at below standard field application rates applied at a vegetative stage of growth (∼14 d after emergence) or at flowering (∼20 d after emergence). Pea seed production was greatly reduced by sulfometuron at the minimum concentration used (0.001 × field application rate), with an effective concentration producing a 25% reduction in seed dry weight of 0.00007 × field application rate. Primisulfuron and glyphosate had a 25% reduction in seed dry weight for seed dry weight of 0.0035 and 0.0096 × field application rate, respectively. Clopyralid and dicamba reduced pea seed dry weight at a 25% reduction in seed dry weight of approximately 0.07 × field application rate. Glufosinate only reduced pea seed weight in one experiment, with a 25% reduction in seed dry weight of 0.07 and 0.008 × field application rate at vegetative growth and flowering stages, respectively. Pea seed dry weight was not affected by 2-methyl-4-chlorophenoxyacetic acid. Plant developmental stage had no consistent effect on herbicide responses. Reduced seed production occurred with some herbicides (especially acetolactate synthase inhibitors), which caused little or no reduction in plant height or shoot biomass and little visible injury. Thus, pea may be a model species to indicate seed reproductive responses to herbicides, with seed production obtained by extending plant growth for usually only 7 d longer than the period usually used in the vegetative vigor test.

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