Magazine R1

A new study of a number ofspecific GM crops over severalyears in rotation with conventionalcrops has found no evidence thatthey may be more harmful to theenvironment, in terms of thereservoir of weed seeds importantfor much wildlife, thanconventional varieties alone.

The findings of the Botanicaland Rotational Implications ofGenetically Modified HerbicideTolerance (Bright) project in theUK studied sugar beet and winteroilseed rape which had beenengineered to make them tolerantof specific herbicides.

The novel crops were grown inrotation with non-GM cereals, andcompared with similar rotationsinvolving non-GM beet and rape.The project concluded that theGM varieties used in this way didnot necessarily deplete the soil ofweed seeds.

The results have been releaseda year after another major GMinvestigation in the UK, called theFarm-Scale Evaluations or FSEs.Both these studies have been partof a far more cautious approachto the introduction of such cropsin Europe, compared with the USand other regions.

The FSEs found that two GMvarieties, a sugar beet and aspring rape, were more damagingto biodiversity than conventionalcrops. There were fewer insectgroups, such as bees andbutterflies recorded among theplants.

A GM maize, on the other hand,appeared to be less damagingthan its conventional cousin.There were more weeds in andaround the biotech maize crops,more butterflies and bees aroundat certain times of year, and moreweed seeds.

The British governmentcautiously opened the way tocultivation of this crop but BayerCropScience, the companyinvolved, said that governmentconditions failed fully to endorseplanting the crop because of thelength of time needed to beginproduction.

A spokesperson for thecompany said that it was unlikelyto get commercialisation of theproduct before 2006 or 2007.“This makes an already ageingvariety old and essentiallyeconomically unviable,” he said.

He said the company wasconcerned that the decision hadbeen influenced by calls for newlegislation on guidelines forfarmers, a legal framework forliability, further biodiversity trialsand rewrites on present andfuture EU licences for thetechnology.

But Elliot Morley, the Britishenvironment minister, defendedthe government’s stance. “We donot apologise for the fact there isa tough EU-wide regulatoryregime on GMs. It applies to thewhole of the EU and not just theUK.”

The British government’sstance, and that of otherregulatory bodies, provides atough backdrop forcommercialisation of the crops inEurope.

FSEs were considerably largerin scale than the Bright project,involving 60–70 fields across theUK. The Bright project focused onsmaller plots but also at sitesaround the UK.

The FSEs were a straightcomparison of GM versus non-GM in each growing season overa few years, whereas the Brightproject aimed to reflect normal

farming practices in eachlocation, indicating how GMvarieties might perform if theywere integrated into UKagriculture.

Jeremy Sweet, the Brightproject’s scientific co-ordinator,believes that in both studies, theimpact on weed seeds is down tothe herbicides used, rather thanthe GM crops themselves. “Thecritical thing is how the herbicidesare used on these crops: so whatwe need to do is to ask whetherthese herbicides have thepotential to do more harm thanthe current ones.”

Sweet concludes that theherbicides used with the GMvarieties can be less harmful thanthose used on the conventionalcrops. “One of the interestingthings about the herbicide-tolerantsystems is that you can apply theherbicides later, when you havegot a much better idea of whatspectrum of weeds is in the field,and therefore you can target yourweed control more effectively.

“This means that you havesome scope for manipulatingpopulations of weeds so that ifyou do want to retain areasonable weed flora in the field,you can do that.

“You can also control theweeds which are competing withthe crop, particularly when thecrop is being established.”

“The most important element ofthe Bright project is the fact that itconfirms comments made in theFSEs about the importance ofmanagement,” says Chris Pollack,who chaired the FSE trials but wasnot involved in the Bright project.“You can use management togenerate rotations that give youthe best balance between weedcontrol and preservation of theseed supply.”

The Bright project did, however,show some potential problemswith cross-breeding betweenherbicide-tolerant varieties ofrape, producing seeds immune tomore than one herbicide.

News focus

Greener light on GM crops

A new study suggests that the management of crop rotation may be ofkey importance in determining the environmental impact of introducinggenetically modified crops alongside conventional crops. But cautionwithin Europe about these crops remains in the face of pressure fromoutside. Nigel Williams reports.

The project researchers foundsome hybridisation betweenplants in adjacent plots ofdifferent herbicide-tolerantvarieties, but this decreasedrapidly with distance between theplots.

Any hybrid oilseed rape plantsemerging in subsequent wheatand barley crops were controlledby standard herbicide programs,however, showing that hybridscontaining more than onetolerance and the single tolerancevarieties are susceptible tostandard cereal herbicides.

Some researchers also believethere could be further problems if,in the future, GM beet and rapewere grown in rotation withcereals which were alsogenetically modified to be tolerantto the same herbicide. “Myexperience of managing weedsover many years is that if you use

the same herbicide year on yearon year, then you will build upproblems,” says Peter Lutman,from Rothamsted Research, oneof the centres involved in theBright project.

But English Nature, the UKgovernment’s wildlife advisorybody, sees nothing to cheer.Having studied the latest findings,it has concluded that the Brightproject supports the evidencefrom the FSEs that the farmingmethods used with modifiedherbicide-tolerant sugar beet andoilseed rape crops can be harmfulto wildlife.

It believes that because weedcontrol in these crops is moreeffective and reliable than forconventional intensive agriculture,it poses a significant threat forwildlife.“This new study adds littleto what we already know aboutthe impacts on wildlife of these

cropping systems,” said BrianJohnson, English Nature’sbiotechnology advisor. “We knowfrom the government’s largerstudy that using these systemswith GM oilseed rape and beetcrops would reduce densities ofwild plants and insects in ouralready impoverishedcountryside,” he says.

Clare Oxborrow, from Friends ofthe Earth, said that the study wasquite limited. “It looked at a verylimited aspect of biodiversity, andit doesn’t really give a definitiveresult in terms of whether the GMcrops were any better or worse forthe environment.”

But the Bright project teambelieve that genetically modifiedcrops can be used to achievebiodiversity objectives andpropose more studies to studyboth these and economicbenefits.

Current Biology Vol 15 No 1R2

Studying on: An earlier trial of genetically modified sugar beet in Europe. There has been widespread consumer and environmentalresistance to any introduction of genetically modified crops in contrast to their widespread acceptance in North America and manyother parts of the world. A new study in Britain finds that genetically modified crops grown under crop rotation plans commonly usedby farmers may have little further environmental impact over their conventional counterparts. (Picture: Science Photo Library.)