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- Title
Appearance of a biotype of the weed, Hordeum glaucum Steud., resistant to the herbicide paraquat.
- Authors
Powles, S. B.
- Abstract
A biotype of the grass weed <em>Hordeum glaucum</em> Steud. infesting a site at Willaura, Victoria, Australia has resistance to paraquat. Application of the recommended rate of paraquat does not cause death of the resistant biotype at any stage of growth. The LD50 for the resistant biotype is 6.4 kg active ingredient ha-1 which is 250 times greater than for the normal susceptible biotype (25 g active ingredient ha-1). Growth of the resistant biotype is checked by paraquat with a clear dosage response evident. The paraquat resistant biotype is also resistant to diquat but is normally affected by herbicides with different modes of action. In addition to continued foliage growth of the resistant plants after paraquat application, seeds of these plants can germinate and seedlings elongate in the dark whereas seeds of susceptible plants germinate but there is no further growth. This suggests that studies of the mechanism(s) conferring resistance will have to consider both the effect of paraquat on the chloroplast and a non-photosynthetic effect on cell growth.
- Subjects
GRASSES; WEEDS; HORDEUM; PARAQUAT; HERBICIDES; CHLOROPLASTS
- Publication
Weed Research, 1986, Vol 26, Issue 3, p167
- ISSN
0043-1737
- Publication type
Article
- DOI
10.1111/j.1365-3180.1986.tb00692.x