Glyphosate-resistant soybeans had lower yields.
Soybean (Glycine max).
CP4 EPSPS gene cloned from Agrobacterium, which produces an
herbicide-resistant version of the enzyme targeted by the herbicide
Goal of This Study:
According to the authors, "potential yield suppression associated with
GR [glyphosate-resistant] cultivars is a concern of producers and seed
companies" (p. 408). This possibility was investigated by comparing the
yields of GR soybean cultivars and their near-isogenic sister lines over
two years at several sites in Nebraska.
Results of This Study:
GR cultivars had on average 5% lower yield than their near-isogenic
sister lines, as well as 4% smaller seed weight.
In a previous study, no significant yield differences were observed when
GR cultivars were sprayed with glyphosate or weeded by hand. In light of
these results, the authors conclude that "yield suppression appears
associated with the GR gene or its insertion process rather than
glyphosate itself" (p. 411).
Elmore, R. W., F. W. Roeth, L. A. Nelson, C. A. Shapiro et al. (2001).
"Glyphosate-resistant Soybean Cultivar Yields Compared with Sister Lines,"
Agronomy Journal vol. 93, pp. 408-12.
University of Nebraska.
Nebraska Soybean Board.
GR soybeans have been grown commercially in the US since 1996 and
currently constitute over 90% of the US soybean crop.
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