EFFECTIVENESS OF ISOLATION DISTANCE IN TURNIP RAPE

Abstract

Isolation distances for turnip rape (Brassica campestris L.) were studied using the recessive genetic marker yg-7. Average contamination levels from six tests over 2 yr were 8.5, 5.8, and 3.7% at isolation distances of 46, 137, and 366 m, respectively. The 46- and 137-m distances were judged to be inadequate, and even the 366-m distance showed greater contamination levels than desirable. No significant border effects were observed and there were no detectable differences in contamination attributable to directional orientation of the isolation blocks with the contaminant source. The data suggest that the 50- and 100-m isolation requirements in Canada for Certified seed production of turnip rape be re-examined and that border removal in lieu of spatial isolation be seriously questioned.