Main content area

Pollen- and Seed-Mediated Gene Flow in Kochia (Kochia scoparia)

Beckie, Hugh J., Blackshaw, Robert E., Hall, Linda M., Johnson, Eric N.
Weed science 2016 v.64 no.4 pp. 624-633
Bassia scoparia, Salsola, acetolactate synthase, alleles, field experimentation, gene flow, glyphosate, herbicide resistance, herbicide-resistant weeds, outcrossing, pollen, pollination, regression analysis, seeds, stubble, wind direction, Alberta, Saskatchewan
Efficient natural dispersal of herbicide-resistance alleles via seed and pollen can markedly accelerate the incidence of herbicide-resistant weed populations across an agroecoregion. Studies were conducted in western Canada in 2014 and 2015 to investigate pollen- and seed-mediated gene flow in kochia. Pollen-mediated gene flow (PMGF) from glyphosate-resistant (GR) to non-GR kochia was quantified in a field trial (hub and spoke design) at Saskatoon, Saskatchewan. Seed-mediated gene flow of acetolactate synthase (ALS) inhibitor-resistant kochia as a function of tumbleweed speed and distance was estimated in cereal stubble fields at Lethbridge, Alberta and Scott, Saskatchewan. Regression analysis indicated that outcrossing from GR to adjacent non-GR kochia ranged from 5.3 to 7.5%, declining exponentially to 0.1 to 0.4% at 96 m distance. However, PMGF was significantly influenced by prevailing wind direction during pollination (maximum of 11 to 17% outcrossing down-wind). Seed dropped by tumbleweeds varied with distance and plant speed, approaching 90% or more (ca. 100,000 seeds or more) at distances of up to 1,000 m and plant speeds of up to 300 cm s⁻¹. This study highlights the efficient proximal (pollen) and distal (seed) gene movement of this important GR weed.Nomenclature: Glyphosate; kochia, Kochia scoparia (L.) Schrad., KCHSC.