Adventitious Presence: Volunteer Flax (Linum usitatissimum) in Herbicide-Resistant Canola (Brassica napus)

Abstract

Flax is in the process of development as a crop for bio-industrial and nutraceutical products predicated on the use of genetic modification. Before genetically modified (GM) flax is commercially released, effective management practices should be developed to minimize adventitious presence (AP) of GM volunteer flax in subsequent crops. Field research was conducted at four locations during 2007 and 2008 in central Alberta to quantify and mitigate AP of volunteer flax in glufosinate-resistant (GR) and imidazolinone-resistant (IR) canola. A single preplant application of glyphosate at 1,250 g ae ha−1in GR canola reduced volunteer flax density from 54 to 3 plants m−2and seed production from 5,963 to 233 seeds m−2. Similarly, the recommended rate of POST glufosinate (600 g ai ha−1) alone effectively controlled volunteer flax and reduced flax seed viability to < 8% and AP to 0.2%. A combination of preplant (glyphosate) and POST (glufosinate) at recommended rates reduced volunteer flax seed production, yield, and AP to near zero in GR canola. Glyphosate applied preplant was equally effective in IR canola, reducing volunteer flax density from 56 to 2 plants m−2, and seed production from 5,571 to 472 seeds m−2. Imazamox + imazethapyr applied POST at all the rates poorly controlled volunteer flax and, even in combination with preplant glyphosate, cannot be recommended for control of flax volunteers in IR canola.

Pollen-mediated gene flow in flax (Linum usitatissimum L.): can genetically engineered and organic flax coexist?

“…Recent GENESYS modeling on gene flow containment in canola (Brassica napus L.) suggest that buffer zones are more effective than isolation zones in reducing harvest admixture because they increased the distance between GE and non-GE fields and diminished the proportion of GE pollen in the total pollen cloud (Colbach et al, 2009). These measures, in addition to practices designed to reduce seed-mediated gene flow (Jhala et al, 2010;Dexter et al, 2010a) may be useful to develop the best management practices to grow GE flax in western Canada.…”

“…Pollenmediated gene flow is only one source of adventitious presence. Contamination of seed for sowing, gene persistence in volunteer populations (Jhala et al, 2010;Dexter et al, 2010a, b) and seed mixing during transport must also be considered. Traditional isolation distances and other management practices designed to segregate crop varieties and production systems to ensure seed and product purity may be insufficient given these constraints.…”

Emergence and Persistence of Volunteer Flax in Western Canadian Cropping Systems

“…Historically, the ranking of crop competitiveness has been cereals > canola > pea (Blackshaw, 1994;Dew, 1972;O'Donovan et al, 2007) although this is being challenged with the introduction of hybrid canola. Weed control in canola is likely to be more effective than in peas where the primary herbicides used are imidazolinones, offering limited control of volunteer flax (Jhala et al, 2010). In the current study, volunteer flax was more abundant in pea fields than canola and cereal fields.…”

“…Volunteer flax can be effectively controlled in wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) by several registered herbicides (Brook, 2007;Wall and Smith, 1999), whereas in pulse crops, such as pea (Pisum sativum L.) and lentil (Lens culinaris Medik. ), or in imidazolinone-resistant canola (Brassica napus L.), effective herbicides are unavailable (Jhala et al, 2010). The GE flax volunteers that survive to set seed may replenish the seed bank or be harvested with subsequent crops resulting in adventitious presence of GE flax in commodity crops (Dexter et al, 2010).…”

Effects of genetic modifications to flax (Linum usitatissimum) on arbuscular mycorrhiza and plant performance

“…Studies on the effect of genetic modifications of flax on plant–AMF interactions are important as GM flax starts to be cultivated in the field and the commercial demand for this crop is large. GM flax lines pose little environmental risk because their seed production and adventitious presence among subsequent crops and yield are relatively easy to control (Jhala et al 2010 ). Nevertheless, mechanisms that the plant uses against pathogens can have deleterious effects also on mutualistic symbionts (Whipps 2004 ).…”