Burial Environment Drives Seed Mortality of Kochia (Bassia scoparia), Wild Oat (Avena fatua), and Volunteer Canola (Brassica napus) Irrespective of Crop Species

Models of weed population demography are critical to understanding the long-term viability of management strategies. The driving factors of weed seedbank persistence are often underrepresented in demographic models due to the cumbersome nature of seedbank research. Simplification of weed seedbank dynamics may induce substantial error in model simulations. A soil bioassay was conducted to determine whether growth of different crop species, including wheat (Triticum aestivum L.), canola (Brassica napus L.), and field pea (Pisum sativum L.), differentially impact seed mortality of kochia [Bassia scoparia (L.) A.J. Scott], wild oat (Avena fatua L.), and volunteer canola in seven burial environments in western Canada. Weed seed survival after the 7 week burial period varied widely among burial environments (from 8% to 88% when averaged among weed and crop species), whereas growth of the different crop species had negligible impact on seedbank persistence. Among environments, wild oat seed survived the greatest (79%), followed by kochia (20%), and volunteer canola (6%). Weed seed survival was associated with soil physical properties (texture) and seed microsite characteristics (temperature), but not crop species or soil chemical properties. Overall, these data support the need for greater integration of soil and environmental parameters into models of weed population demography.