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Unintended Effects of Genetic Manipulation
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Fruiting morphology was altered when glyphosate-resistant cotton was sprayed with glyphosate.

Manipulated Organism: Cotton (Gossypium hirsutum).

Inserted Transgenes: CP4 EPSPS gene cloned from Agrobacterium, which produces an herbicide-resistant version of the enzyme targeted by the herbicide glyphosate (Roundup).

Goal of This Study: To investigate whether the timing and method of glyphosate application to glyphosate-resistant (GR) cotton affects fruiting morphology, yield, and fiber quality.

Results of This Study:
  • Several differences in fruiting morphology, such as a reduction in the number of early fruits (bolls), were observed in the field when GR plants were treated with glyphosate. The most pronounced differences were seen with late (beyond the four-leaf stage) foliar applications of glyphosate, which are technically not allowed (off-label), but even "treatments applied within label guidelines may unpredictably impact fruit retention in certain years or conditions" (p. 28).

  • At one field site, a small (6%) but statistically significant reduction in seed cotton yield was observed when GR plants received late (off-label) foliar applications of glyphosate.
Source: Pline-Srnic, W. A., K. L. Edmisten, J. W. Wilcut, R. Wells et al. (2004). "Effect of Glyphosate on Fruit Retention, Yield, and Fiber Quality of Glyphosate Resistant Cotton," Journal of Cotton Science vol. 8, pp. 24-32.

Author Affiliations: Syngenta; North Carolina State University.

Funding: North Carolina Cotton Growers; Cotton Incorporated.

Product Status: GR cotton is grown worldwide, including since 1997 in the U.S.

Copyright 2009 The Nature Institute.

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