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The fate of wild sunflower seeds and its population biology consequences.
Schrag, Anne1, Nash, Joseph1, Alexander, Helen1, 1
ABSTRACT- Seeds of the wild annual sunflower, Helianthus annuus, can be long-lived in the soil but also are large and susceptible to predation. To evaluate factors affecting the fate of seeds in northeastern Kansas, seeds were sealed in fiberglass screen packets and buried at 10cm depth. Additional treatments examined the fate of seeds on the soil surface (i.e. dormancy, germination and predation) in the presence and absence of litter. Eighty-one percent of the buried seeds were dormant but viable after one year compared to 26.3% of the surface seed. Of the non-dormant surface seeds, 24.9% germinated and 48.8% disappeared (presumed predation). After one year, litter had reduced germination from 30.8% in plots without litter to 19.0% in those containing litter. We are currently using a field experiment to evaluate the relative importance of the current year's seed production versus recruitment from dormant seeds in the soil on the population biology of wild sunflowers.
KEY WORDS: seeds, wild sunflower, dormancy, litter