THE RESULTS of a four-year study of GM herbicide-tolerant crops and non-GM crops at five sites in the UK show that GM crops have benefits of interest to farmers.

The BRIGHT project found that weed control was generally most effective in the glyphosate-tolerant crops and that more weeds occurred in the herbicide-tolerant crops than in the intervening crops of non-GM winter cereals.

No significant decreases in species diversity were observed. Weed seed banks increased in both winter oilseed rape and sugar beet rotations between the start and end of the four-year study.

“This project is unique in the world in that it has studied the implications both for agriculture and the environment of growing more than one GM crop in a rotation,” said project chairman Windsor Griffith at a press conference in London on Mon (Nov 29).

The project found no observable direct impacts of the transgenes themselves.

The only differences observed were due to the different herbicide programmes.

No major differences in plant populations on land planted with GM and with non-GM crops was recorded, but the research indicated that GM crops can provide farmers with greater flexibility in the application of herbicides for the control of weeds.

The project, funded partly by DEFRA and partly by the biotech industry, found that the herbicide-tolerant crops offer farmers cheaper and more flexible farm management options than what conventional crops offer.

But the researchers identified one major drawback when planting conventional oilseed rape in rotation after a GM winter oilseed rape: The persistence of GM rape seeds in the soil.

“There is no scope for weeding out the GM rape plants from the non-GM rape crop,” the researchers said in a statement.

Friends of the Earth said that the study results appeared to confirm fears that, if released commercially, GM crops will be difficult to control and will cross-pollinate with non-GM crops.

The Agricultural Biotechnology Council, on the other hand, emphasised that GM crops can be grown in a manner that benefits both the environment and farmers‘ bottom line.