Isolation distance for genetically modified plants
From Wikipedia, the free encyclopedia
 |
This article does not cite any references or sources. (April 2008) Please help improve this article by adding citations to reliable sources. Unverifiable material may be challenged and removed. |
Isolation distances are used in regions where genetically modified (GM) and conventional or organic crops are grown in co-existence. When different cropping systems are grown in proximity to each other, the "isolation distance" between fields refers to the area separating them, on which genetically modified pollen can settle without fertilising non-GM crops.
Contents |
[edit] Goal of isolation distances
The goal of isolation distances is to minimise out-crossing of GM plants. If large amounts of GM pollen fertilise crops in a non-GM field, that harvest may no longer be declared "GM-free", and will require appropriate labelling if its GM content exceeds a certain limit (e.g. 0.9 percent in the European Union).
[edit] Design of isolation distances
Isolation distances are mostly empty spaces. They may be roads, uncultivated fields, or anything that separates two fields without actively hindering the drift of pollen. Separation methods between GM and non-GM fields which actively catch pollen are called "pollen barriers" or "buffer zones".
[edit] Factors influencing isolation distances
Many factors influence the width required for isolation. A major criterion is the crop species, since isolation distances often must be calculated according to pollen weight. Other influential criteria include the size and shape of fields, GM-contamination tolerance levels and, especially, local wind direction and weather conditions.
[edit] Isolation distances for maize
Maize is probably the best-studied crop in terms of isolation distances. Yet, recommendations for isolation distances have varied significantly. Under average conditions, the isolation distance may be 25 metres. However, in regions with small non-GM fields (< 1 hectare), or with crops being grown primarily for seed production, the isolation distance may be more than 100 metres.
[edit] Research on isolation distances
Among dozens of individual research projects, there are two extensive programmes investigating isolation distances for relevant crop species: SIGMEA and Co-Extra. Further results from various projects have been compiled by GMO-Safety.eu.
