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This article in CS

  1. Vol. 47 No. 5, p. 2058-2066
    Received: Jan 16, 2007

    * Corresponding author(s): bhanson@fresno.ars.usda.gov
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Recovery of Imidazolinone-Resistant Hard Red Wheat Lines Following Imazamox Application

  1. Bradley D. Hanson *a,
  2. Lynn Fandricha,
  3. Dale L. Shanerb,
  4. Philip Westraa and
  5. Scott J. Nissena
  1. a Dep. of Bioagricultural Sciences and Pest Management, Colorado State Univ., Fort Collins, CO 80523
    b USDA-ARS Water Management Unit, 2150 Centre Ave., Bldg. D, Suite 320, Fort Collins, CO 80526. B.D. Hanson's current address is USDA-ARS Water Management Research Unit, 9611 S. Riverbend Ave., Parlier, CA 93648. This article is a U.S. government work and is in the public domain in the USA


Imidazolinone-resistant hard red wheat (Triticum aestivum L.) cultivars are occasionally injured by imazamox applications because a portion of the acetolactate synthase (ALS) remains susceptible to the herbicide. The growth and enzyme activity of two groups of hard red wheat near-isolines with spring or winter growth habit were examined following imazamox application. Each group of near-isolines contained a susceptible cultivar and cultivars with the imidazolinone-resistant trait on either the B or D genome. The spring wheat group also contained a line carrying both the B and D genome copies of the resistance gene. In whole plant experiments, growth of all single-gene resistant lines was delayed by both 35 and 105 g ha−1 imazamox while the two-gene line was delayed at only the highest rate. There was a herbicide rate effect on biomass accumulation but no differences among genome locations in the single-gene resistant lines or among spring vs. winter growth habit. On an ALS enzyme basis, however, there were differences among B- vs. D-genome resistance and between winter and spring growth habit. Spring wheat cultivars with the B-genome resistance had greater reductions in ALS activity compared to the D-genome cultivars, while in winter wheat, B- and D-genome lines responded similarly. Differences among genotypes existed in the recovery of ALS activity in imidazolinone wheat but other factors also likely influence the injury occasionally observed in the field.

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