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Quantification and risk assessment of seed-mediated gene flow with flax as a platform crop for bioproducts Open Access


Other title
biosaftey, gene flow, volunteer flax, persistence, fecundity, mitigation
Type of item
Degree grantor
University of Alberta
Author or creator
Dexter, Jody Elaine
Supervisor and department
Dr. Linda Hall (Agriculture, Food and Nutritional Science)
Examining committee member and department
Dr. Christian Willenborg (Agriculture, Food and Nutritional Science)
Dr. Randall Weselake (Agriculture, Food and Nutritional Science)
Dr. Melissa Hills (Biology, Grant MacEwan College)
Dr. Clarence Swanton (Weed Science, Weed Ecology, Cropping Systems, University of Guelph)
Dr. Micheal Deyholos (Biological Sciences)
Department of Agricultural, Food and Nutritional Science

Date accepted
Graduation date
Doctor of Philosophy
Degree level
Flax (Linum usitatissimum L.) is being considered as a platform crop for the development of bioproducts. Potential benefits of bioindustrial farming include the provison of bioenergy and biomaterials, and opportunities for biorefining. Prior to the commercialization of crops intended for bioproducts however, the safety of the food/feed system and the environment must be assured. As part of a preliminary biosafety assessment I conducted a literature review and experiments to quantify seed-mediated gene flow from flax to the environment and food/feed system. Flax seed losses at harvest, seed persistence in soil, efficacy of herbicides to control volunteer survival and fecundity in subsequent crops, volunteerism (density and occurrence) and volunteer emergence periodicity in follow crops in commercial fields were examined. Total seed losses at harvest in commercial fields were variable (2.7 to 44.2 kg ha-1). Flax has a short longevity in the seed bank (2 to 3 years). Flax has been selected for reduced seed dormancy and volunteer flax seed persistence may be hastened by burial. Compared to other domesticated crops, flax has a prolonged period of emergence and calculated EM50 values (the growing degree days required for 50% emergence) ranged from 227 to 340 growing degree days (GDD). Flax volunteers reached their period of peak emergence earlier in conventional tillage than in reduced tillage fields. Volunteer flax densities were highest prior to herbicide applications (10.4 to 570.2 plants m-2) in all fields the year following flax production (2005) and diminished over time. Volunteers that emerge in the spring may be controlled with registered herbicides. Glyphosate and fluroxypyr tank-mixed with either monohydrate sodium salt of 2,4-dicholorophenoxy acetic acid (2,4-D) or monochlorophenoxyacetic acid Ester 500 (MCPA) were most effective in reducing volunteer flax density, biomass, and fecundity. These herbicides also reduced the adventitious presence of volunteer flax seed in spring wheat (from over 8.5% to 0.16%). Best management practices could be adopted to mitigate seed-mediated gene flow from flax in agricultural productions systems, but thresholds of zero are not biologically realistic. The agronomic baseline data generated in this thesis however, suggests that flax may be an appropriate crop platform for bioindustrial products.
License granted by Jody Dexter ( on 2009-09-10T16:55:57Z (GMT): Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of the above terms. The author reserves all other publication and other rights in association with the copyright in the thesis, and except as herein provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
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