Agriculture Reference
In-Depth Information
of a specific country or internationally) and that different types of costs
have to be distinguished when assessing the economic impacts of coex-
istence measures in agricultural production (Menrad, 2003). However, a
lot of questions could not be clarified in these studies, in particular with
respect to production of certified seeds. Therefore, thresholds for the
adventitious presence of GM seeds in conventional seeds are still under
discussion in the EU.
2. Economic Effects of Coexistence Measures
in Maize Crop and Seed ProductioninFrance
France is the leading maize producer in Europe (EU 15). The Poitou-
Charentes region has been chosen for a case study for maize crop produc-
tion because it represents the third largest grain maize producing region
and accounts for about 11 percent of the area under maize in France. Fur-
thermore, GM maize varieties are an alternative for farmers with prob-
lems of controlling weeds and European or Mediterranean corn borer
infestations.
Both in the case of maize crop and maize seed production, the co-
existence MAPOD
R
gene flow model (Angevin et al., 2001) was used
to estimate adventitious presence of GM maize varieties due to cross-
pollination. This model was developed during a study that aimed to
assess the economic relevance and technical feasibility of non-GM sup-
ply chains in France (Le Bail &Meynard, 2001). Input data of the model
refer to field structure (e.g., form and size of fields, location of specific
plant varieties), climate (e.g., temperature, rain, speed, and direction of
the wind), cropping systems (like e.g., sowing dates, drought stress before
and during flowering), and the variety (e.g., quantity of pollen per plant,
pollen sensitivity to temperature, genotype of GMO, tassel height of the
variety). The model estimates the rate of variant impurities due to cross-
pollination in maize as well as changes in these rates due to changes in
cropping techniques (Angevin et al., 2001).
