Author
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Conn, Jeffery |
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Werdin Pfisterer, Nancy |
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Submitted to: Weed Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 2/23/2010 Publication Date: 10/1/2010 Citation: Conn, J.S., Werdin Pfisterer, N.R. 2010. Variation in seed viability and dormancy of 17 weed species after 24.7 years of burial: the concept of buried seed safe sites. Weed Science. 58(3):209-215. Interpretive Summary: Weeds emerge and compete with other plants as long as there is a bank of viable seeds in the soil. To determine wether its feasible to eradicate a weed species, it is important to know how long the seed will remain viable in the soil. A 50-year study at Fairbanks, AK was started in 1984 to determine soil seed longevity of 17 weed species. Seeds were buried in mesh bags 2 and 15 cm deep and were recovered 0.7, 1.7, 2.7, 3.7, 4.7, 6.7, 9.7,19.7 and 24.7 yr later. Viability was determined using germination and viability staining tests. By 24.7 years after burial (YAB) no viable seeds were found for common hempnettle, quackgrass, wild oat, foxtail barley and flixweed. Bluejoint reedgrass which had no live seed 19.7 YAB again had viability (1%) 24.7 YAB. Seeds of 11 other species were still viable: corn spurry (0.2%), prostrate knotweed (2.8% at 15 cm), pineapple-weed (2.7%), shepherd’s-purse (2.8%), wild buckwheat (0.3%), common chickweed (0.4%), rough cinquefoil (2.3%), common lambsquarters (2.8%) Pennsylvania smartweed 1.2%), marsh yellowcress (6.9%), and American dragonhead (51.9%). During the course of this study, seed longevity declines were uniform between replicates at the beginning of the study but, for all species except American dragonhead, variability between replicates increased through time, suggesting that some soil micro-sites are more favorable for seed survival and may “safe sites” for seeds. Non-random seed mortality contributes to the heterogeneity of the soil seed bank and makes it more difficult to gauge the size of the soil seed bank. Thirteen weed species continue to have seed viability even after 24.7 years of burial demonstrating the importance of preventing spread of weeds to new areas. Technical Abstract: A 50-year study at Fairbanks, AK was started in 1984 to determine soil seed longevity of 17 weed species. Seeds were buried in mesh bags 2 and 15 cm deep and were recovered 0.7, 1.7, 2.7, 3.7, 4.7, 6.7, 9.7,19.7 and 24.7 yr later. Viability was determined using germination and tetrazolium tests. By 24.7 years after burial (YAB) no viable seeds were found for common hempnettle, quackgrass, wild oat, foxtail barley and flixweed. Bluejoint reedgrass which had no live seed 19.7 YAB again had viability (1%) 24.7 YAB. Seeds of 11 other species were still viable: corn spurry (0.2%), prostrate knotweed (2.8% at 15 cm), pineapple-weed (2.7%), shepherd’s-purse (2.8%), wild buckwheat (0.3%), common chickweed (0.4%), rough cinquefoil (2.3%), common lambsquarters (2.8%) Pennsylvania smartweed 1.2%), marsh yellowcress (6.9%), and American dragonhead (51.9%). Seed dormancy 24.7 YAB was 0 or very low for all species (< 10%) except American dragonhead, shepherd’s-purse, marsh yellowcress, rough cinquefoil, and Pennsylvania smartweed which had seed dormancies of 99, 40, 23, 14 and 18%, respectively. During the course of this study, seed longevity declines were uniform between replicates at the beginning of the study but, for all species except American dragonhead, variability between replicates increased through time, suggesting that some soil microsites are more favorable for seed survival and may be seedbank “safe sites”. Spatially non-random seed mortality contributes to the heterogeneity of the soil seedbank. |
