Seedbank persistence, germination and early growth of glyphosate‐resistant Kochia scoparia

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Summary This study describes the seedbank persistence of glyphosate‐resistant ( GR ) Kochia scoparia at two sites in western Canada and examines if GR K. scoparia from western Canada and mid‐western United States ( USA ) differ from their susceptible counterparts in seed germination and early growth characteristics at low‐temperature regimes. Site or depth of seed burial (surface, 2.5 cm, 10 cm) did not affect seed viability over time and time to 50% and 90% loss of viability averaged 210 and 232 days respectively. Glyphosate‐resistant K. scoparia generally germinated later and had lower cumulative germination than glyphosate‐susceptible ( GS ) K. scoparia from Saskatchewan, Canada; and Kansas, USA ; but not Colorado, USA . Similarly, time to 10% first leaf of GS K. scoparia from Saskatchewan and Kansas tended to be sooner than that of GR K. scoparia , with a greater percentage of GS vs. GR seedlings of populations from all regions having attained first leaf by the end of the experiment. The short seedbank longevity and delayed and reduced germination and time to first leaf of GR K. scoparia may potentially be exploited to maximise management efficacy through delayed preseeding weed control or alternatively by early seeding date to enhance crop competitiveness.