GENESYS: a model of the influence of cropping system on gene escape from herbicide tolerant rapeseed crops to rape volunteers - I. Temporal evolution of a population of rapeseed volunteers in a field

The aim of model GENESYS is to rank cropping systems according to their risk of gene escape from genetically modified, herbicide tolerant winter oilseed rape cultivars to rapeseed volunteers. The model integrates the effects of crop succession and crop management at the level of a region. The first part of the model presented in this paper describes the temporal evolution of rapeseed volunteers in a field, using an annual Life-cycle comprising stages such as seed bank, seedlings, adult plants, Rowers or freshly produced seeds. The relationships between the various stages depend on the crops grown each year and the cultivation techniques (stubble breaking, soil tillage, sowing date and density, herbicides, cutting and harvesting). Parameter values were either deduced from existing models and literature, or estimated from experimental studies and field surveys. The extension of the temporal sub-model to include the genetic evolution of rapeseed volunteers and the spatial dimension is presented in a second paper [Colbach, N., Clermont-Dauphin, C., Meynard, J.M., 2001. Agric. Ecosyst. Environ.]. (C) 2001 Elsevier science B.V. All rights reserved.