Environmental regulators have given state science company Crop and Food Research a long-term approval for field tests of a wide range of engineered plants in the onion family.
Controversially, the Environmental Risk Management Authority will allow the genetically engineered onions to set seed in a Canterbury field.
Itis the fourth GE field trial approved since 2001 when the Royal Commission on Genetic Modification said New Zealand should "proceed with caution" on biotechnology research.
The scientists will allow the GE onions to flower in the field, covered by cages which will effectively be a death row for insects placed in the cages to pollinate the flowers - they will not be allowed to escape alive.
The regulators have said it is "highly improbable" viable plant material will escape the 10-year field test of GE onions, spring onions, leeks and garlic.
Conventional onions are a slow-growing crop, poor at fighting off weeds. Farmers use a battery of up to 15 different herbicides to control weeds, and many of the herbicides are more toxic and longer-lasting than glyphosate.
But the trials over the next 10 years are expected to cover a wider stance than Crop and Food's earlier efforts, such as in 2002 when it argued that Roundup-tolerant onions could save the country $2.25 million a year because growers could reduce the amount of sprays they used. Some of the plants are expected to be modified for use with beneficial insects.
The tests will assess the plants' performance in field conditions, with no more than 2.5ha planted at a time.
The many controls on the trial include a requirement for the cages to comprise a rigid framework covered with a double layer of fine-mesh material, said the chairwoman of the authority's decision-making committee, Helen Atkins.
Laboratory-bred maggots will be put into the cages to mature into flies which will carry out pollination, and all of them must be killed before the cages are opened, she said.
All GE material no longer required must be killed on-site by composting or be removed for further research or destruction in containment.
Researchers must check the pollination cages daily for damage or dislodgment which could allow insects to escape carrying pollen, and the project will be monitored by the Ministry of Agriculture and Forestry.
There will also be two years' monitoring at the site after the field trial to check that no "volunteer" plants from the trial grow.
