Seed Viability and Dormancy of 17 Weed Species After Burial for 4.7 Years in Alaska

Abstract

Seed of 17 weed species that were buried at 2 and 15 cm at Fairbanks, AK, in 1984 were exhumed at 1-yr intervals and tested for germination and viability. Burial depth had a significant effect on seed viability of wild oats, bluejoint reedgrass, quackgrass, prostrate knotweed, and corn spurry with viability remaining higher at 15 than at 2 cm. The percent of viable foxtail barley and quackgrass seed that were dormant was greater at 15 than at 2 cm. Eleven of 17 species had greater than 6% seed viability 4.7 yr after burial. American dragonhead seed viability in 1989 was not significantly lower than in 1984. In contrast, viability of common hempnettle and quackgrass had dropped to zero by 2.7 and 3.7 years after burial, respectively. Foxtail barley and wild oats had less than 1% viable seed at the end of 4.7 yr. For most of the 17 species, a rectangular hyperbola model accounted for more of the variability in seed viability decline with time than did a negative logarithmic model.