Contamination in Denta Sweetclover During Successive Generations of Seed Increase¹

Abstract

Contamination levels observed in the breeder, foundation, and certified seed generations of ‘Denta’ sweetclover (Melilotus alba Desr.) were 0.71, 1.69, and 3.62%, respectively, as measured by the frequency of plants high in content of ο‐hydroxycinnamic acid. Based on a sample of plants tested simultaneously for ο‐hydroxycinnamic acid content and β‐glucosidase activity, a small but consistent decrease in the frequency of cu plants occurred with succeeding seed generations, while shifts in the frequency of b plants were not consistent in magnitude or direction. Contamination through cross‐pollination with CuCuBB plants may be the major factor responsible for the observed decreases in the frequency of cu plants.

Ecological Risks of Transgenic Plants: Effects of Spatial Dispersion on Gene Flow

“…Researchers felt that if a crop is harvested before seed dispersal is possible, even if some very small number of plants had received pollen from neighboring weeds, the field should remain free of contamination. But even in an agricultural setting, foreign genes have been known to spread through subsequent generations (Goplen andWeber 1966, Gorz andHaskins 1969). Apparently it is often difficult and expensive for farmers to distin-guish crop/weed hybrids.…”

Effects of Isolation Distance on Contamination in Sweetclover

“…ffi ;'",. (Goplen and weber 7966; Gorz and Haskins 1969) and the necessity of keeping contamination Ievels below l0% in low coumarin cultivars (Goplen et al 1964), it would appear highly desirable to increase isolation requirements, particularly of the Foundation class.…”