19 December 1997

GMHT crops may need no change in management

Helping farmers, lobby

groups and the public

understand genetically

modified crops is the goal of

an EU-funded project.

Charles Abel reports on

results to date

GENETICALLY modified herbicide tolerant crops are unlikely to need any change to their management apart from their weed control programme.

Trials across Europe show the nitrogen response, yield potential, fungicide response and lodging potential of GM crops are no different from conventional varieties.

But the trials do suggest a northern limit for GMHT spring rape production and a possibly greater susceptibility to sclerotinia and alternaria. Spring GMHT rape may also be better able to cope with late drilling.

During 1997 345 agronomy trials were conducted in the UK, France, Belgium, Germany, Denmark and Sweden. Both winter and spring varieties of GMHT oilseed rape from the AgrEvo/PGS Liberty Link glufosinate tolerant programme were tested.

"Yield clearly varied, but this was according to variety and not whether a crop was GM," said Greta de Both of PGS (Belgium) at last weeks meeting of the EU-funded FACTT (Familiarisation and Acceptance of Crops containing Transgenic Technology) project.

The same applied to agronomy. Although GMHT varieties were taller, lodging was not affected. Quality varied between varieties, but not types, and no difference was seen in response to N.

No differences were apparent in the level of weed control or phytotoxicity between conventional herbicide and total herbicide programmes on either conventional or GMHT varieties. But economic studies showed a cost benefit would be possible, depending upon the cost of seed, she said.

For winter rape delayed drilling cut yield in GMHT types as much as for conventional rape, ending hopes that the more vigorous GMHT hybrids could be sown later.

But UK trials showed spring GMHT rape suffered very little yield loss where sowing was two or four weeks later than ideal.

Of more concern Swedish trials suggested northern crops of spring GMHT rape were more susceptible to yield loss than conventional varieties. Plots grown at a latitude comparable with Berwick yielded normally, but those grown further north suffered lower yields, despite vigorous growth. Day length may be to blame, it was suggested.

In Denmark the trials revealed significantly higher levels of sclerotinia and alternaria in two of the winter GMHT lines.

First-year results from the Europe-wide FACTT project show GM herbicide tolerant OSR can be managed in just the same way as conventional varieties. GMrape with a modified oil profile should be on show next year.