Abstract: The invention provides a method for biasing a crop plant which is heterozygous for a transgene towards the production of seeds which carry the transgene comprising the step of contacting the crop plant containing a gene construct comprising the transgene coding for resistance to a specific phytotoxin with the specific phytotoxin one or more times during the life of the crop plant. The method achieves this through selective inhibition of phytotoxin-sensitive plant ovules, embryos and pollen. The method has particular application to the production of open pollinated and synthetic varieties of crop plants, such as alfalfa synthetic varieties.