More Information on Background: Factors Affecting Cross-Pollination

Although most farmers in industrialized nations purchase new seed for hybrid crops every year, many in developing countries selectively save seed from one growing season for planting during subsequent seasons. Studies have shown that these farmers may purchase seeds from commercially improved maize varieties not only for producing that variety and saving its seeds, but also to intentionally incorporate the improved germplasm into local cultivars and landraces (Bellon and Brush, 1994; Louette and Smale, 1996; Louette et al., 1997). If farmers save and share seeds derived from either the commercial variety or the hybrid (commercially improved variety x landrace) with other local farmers, then introgression of the new genetic material can occur. With the exception of soybeans in the U.S. and Canada, seed saving of non-hybrid crop seed is common in all countries, regardless of the level of industrialization. Also, some farmers in developing countries purchase grain intended as livestock feed and use it for seed.