Journal of Agronomy and Crop Science
Volume 193 Issue 2 Page 79 - April 2007
Coexistence Between GM and
Non-GM Maize Crops – Tested in 2004 at the Field Scale Level
(Erprobungsanbau 2004)
W. E. Weber, T. Bringezu, I. Broer, J. Eder, F. Holz (2007)
Journal of Agronomy and Crop Science 193 (2), 79–92.
doi:10.1111/j.1439-037X.2006.00245.x
ABSTRACT
The objective of the study was to
test the feasibility of coexistence between genetically modified
(GM) and non-GM maize under real-life agronomical conditions. GM
hybrid maize with the event MON810 (Bt maize) was drilled at 30
sites in fields surrounded by near isogenic conventional maize,
although only 27 sites could be finally evaluated. Field sizes
of Bt maize varied between 0.3 and 23 ha, and the flowering
period of the Bt and conventional maize was synchronous. At some
sites, different planting dates of GM and non-GM maize or an
earlier ripening conventional maize were tested in additional
strips to obtain altered flowering and thereby reduce
cross-pollination. The overlapping of flowering periods was
successfully avoided only at two sites where non-GM maize was
planted 25 or 28 days later. During harvest, samples were taken
from the conventional maize in strips at distances of 0–10,
20–30, and 50–60 m to the Bt maize fields to assess the GM DNA
content as a function of distance. Sampled materials included
chaffed plant material intended for silage (18 sites), grains
(eight sites), or crushed husks and cobs (one site). Wind
effects were taken into account by sampling in all four compass
directions. Quantitative PCR was used to detect the event
specific MON810 DNA sequence in sampled materials. The analysis
was conducted by two certified independent diagnostic testing
companies selected in a pre-test. Taking averages over all
compass directions and the two laboratories no samples collected
beyond 10 m had levels of GM above the threshold of 0.9 %. In
conclusion, the data indicate that coexistence of GM and
conventional maize is possible under real-life large-scale
agronomical conditions. Levels of GM DNA in harvested grain
resulting from outcrossing can be managed to levels below 0.9 %
by simply planting 20 m of conventional maize as a pollen
barrier between adjacent fields.
Full article:
http://www.blackwell-synergy.com/doi/abs/10.1111/j.1439-037X.2006.00245.x
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