1 December 1995

Volunteer dilemma

INDUSTRIAL oilseed rape growers face a serious volunteer problem from new genetically engineered varieties.

"Oilseed rape is already a major industrial crop. It has potential to develop further as new modifications are made to its fatty acid composition," said Melvyn Askew, head of ADASs Alternative Crops and Biotechnology unit.

Five different oil-bearing rapes will be available by the end of the decade, he predicts.

"Unfortunately, at least 1% of the crop is shed at harvest, six times the normal seed rate." Seed can remain viable up to 10 years after shedding, he notes. "Ensuing crops of the same species could be contaminated to an unacceptable level."

"Gene stacking" could cure that, he suggested. Each different rape type would contain a different herbicide tolerance, allowing removal of volunteers without harming the crop.

Using different species could help. Linseed, sunflower and crambe are possibilities. But they are less profitable to grow than rape so are unlikely to benefit as much from the new technology, he suspected.