2001 AACC Annual Meeting Charlotte, North Carolina October 14-18, 2001 Charlotte Convention Center

Wheat (Triticum aestivum L.) is a self pollinated species with out-crossing (OC) rates that are assumed to be less than 1%. A field study of three market classes of Canadian spring wheat detected cultivar OC rates ranging from 0.3 to 6.1% at a distance of 20 cm from the pollen source. Cultivars with higher OC rates tended to have tapered spikes, a greater degree of spikelet opening at anthesis and/or poorer pollen quality. When cultivars with high OC rates were compared to those with low OC rates, the former were subject to genetic contamination at distances of up to 27 meters from a 25 m(^2) pollinator block. Cultivars not prone to OC did not exhibit genetic contamination beyond three m in the same field study. Pollen spread in a plume that was dependent on wind direction at anthesis. Currently, little is known regarding gene flow at the commercial wheat production level. Based on small-scale pollen flow studies, one would expect a very low rate of gene flow between GM and non-GM wheat fields. The rate of gene flow in wheat will be magnitudes lower than that encountered with cross-pollinated crops. However, once GM wheat is commercialized, maintaining the integrity of non-GM wheat at a 100% level will be unrealistic. Maximum tolerances for co-mingling need to be established. Gene flow via pollen movement will set the biological base-line for co-mingling. Agronomic and grain handling factors are likely to over-shadow pollen flow as a source of co-mingling in commercial wheat.