Volume 11, Number 1, Janvier-Février 2004
|Page(s)||11 - 20|
|Published online||15 January 2004|
Using the GENESYS model quantifying the effect of cropping systems on gene escape from GM rape varieties to evaluate and design cropping systems
UMR Biologie et Gestion des Adventices, INRA, BP 86510, 17 rue Sully, 21065 DIJON Cedex, France
2 INRA Eco-Innov, BP 01, 78850 Thiverval-Grignon, France
3 UMR d’Agronomie, INRA INA P-G, BP 01, 78850 Thiverval-Grignon, France
4 Cetiom, Centre de Grignon, BP 4, 78850 Thiverval-Grignon, France
Gene flow in rapeseed is a process taking place both in space and over the years and cannot be studied exclusively by field trials. Consequently, the GENESYS model was developed to quantify the effects of cropping systems on transgene escape from rapeseed crops to rapeseed volunteers in neighbour plots and in the subsequent crops. In the present work, this model was used to evaluate the risk of rape harvest contamination by extraneous genes in various farming systems in case of co-existing GM, conventional and organic crops. When 50 % of the rape varieties in the region were transgenic, the rate of GM seeds in non-GM crop harvests on farms with large fields was lower than the 0.9 % purity threshold proposed by the EC for rape crop production (food and feed) harvests, but on farms with smaller fields, the threshold was exceeded. Harvest impurity increased in organic farms, mainly because of their small field size. The model was then used to evaluate the consequences of changes in farming practices and to identify those changes reducing harvest contamination. The effects of these changes depended on the field pattern and farming system. The most efficient practices in limiting harvest impurity comprised improved set-aside management by sowing a cover crop in spring on all set-aside fields in the region, permanently banning rape crops and set-aside around seed production fields and (for non-GM farmers) clustering farm fields to reduce gene inflow from neighbour fields.
Key words: model / cropping system / gene flow / oilseed rape GM crops / coexistence
© John Libbey Eurotext 2004
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