| Popis: |
Coexistence between farmers using different crop production systems needs tolerance, since the growing of plants represents an open system and a perfect separation of plant materials between neighbouring fields is not possible. In the case of genetically modified (GM) plants, the situation is complicated, since not only the farmers themselves are involved. To achieve coexistence, accepted threshold values for labelling and distance measures for separation of fields with different cropping systems have been introduced, as well as rules on how to handle problems. Since organic agriculture is only a production system, the same threshold values for organic products are valid as for conventional products. Nevertheless, different minimum distances are prescribed in Germany for GM maize, the only crop for which released varieties exist for that country. Since GM agriculture is allowed only for varieties that have passed all required safety checks, admixture can only have economic consequences as a result of price differences between organic and labelled GM products. The restriction to product prices alone is facilitating coexistence. Nevertheless, it should be kept in mind that there remains a clash in basic thinking and consequent practical implementation between organic farming and conventional and GM farming; this can affect even social relationships between neighbouring farmers. Gene flow can be reduced by increasing the distances between fields, buffer zones, the use of genotypes differing in flowering time and taking wind direction into account. However, environmental factors such as wind cannot be predicted in advance. This restricts the value of modelling environmental factors in order to manage gene flow. Since GM plants behave as other plants, gene flow as an important force of evolution cannot be suppressed completely. However, this is not unique to GM crops. |
