Bt, Non-Bt Maize Coexistence Tested in Germany

Results of a pre-commercial field scale trial conducted in 30 sites in Germany demonstrated that coexistence between Bt maize and the non-transgenic counterpart is possible. The study conducted by W. E. Weber and colleagues at the Martin Luther University, showed that levels of the transgene in the grains of the non-transgenic maize can be kept below 0.9 percent, the threshold level for labeling GM products in the European Union.

The group of Weber grew maize in field sites ranging from 0.3 to 23 hectares in size. In all areas, a Bt maize hybrid containing transgenic event MON810 was planted in the middle of the field and surrounded by non-Bt maize. The maize flowering times were overlapping. During harvesting, the researchers obtained plant samples from the non-Bt maize located 0 to 60 meters away from the Bt maize. The DNA of the samples was analyzed by two diagnostic laboratories where real-time PCR was used to detect the levels of the transgene.

The study has determined that no samples from the conventional maize collected beyond 10 meters had levels of GM above the threshold of 0.9 percent. The researchers recommend that planting 20 meters of conventional maize as a pollen barrier between adjacent fields is sufficient in managing the outcrossing between Bt and non-Bt maize.

Subscribers to the Journal of Agronomy and Crop Science can access the full article at http://www.blackwell-synergy.com/doi/abs/10.1111/j.1439-037X.2006.00245.x