Crop Specific Safety Concerns Maize

Every crop has a different relationship to the environment, which means environmental impact assessments must be conducted on a case-by-case basis. Different crops pose different threats when it comes to out-crossing or escaping cultivation. The following plant specific characteristics are taken into account for risk assessment.

General information

Maize is a plant not known to exist outside of cultivation. It is believed to have originated from a Mexican grass called Teosinte in prehistoric times. Maize has a specialised physiology known as "C4" photosynthesis, which makes it well suited to hot, dry climates. Due to extensive breeding, however, maize can now be grown in colder, temperate places like Canada and Russia.

Is out-crossing of transgenes from maize possible?

Originating from South America, maize (Zea mays) has no wild relatives in Europe. Hybridisation partners are restricted to other maize plants.

Maize is wind-pollinated. Maize pollen is relatively heavy, which means it cannot be carried by wind over very long distances. Additionally, maize pollen loses viability after approximately two hours. These factors can vary depending on humidity and temperature.

Tests on Bt maize revealed that out-crossing with neighbouring maize fields occurs at a rate of approximately 1 percent at a distance of 10 m, upwind; when downwind, 1 percent out-crossing was observed at 28 m.
Maize plants can be stripped of their pollen-forming, male flowers (tassels). Also known as decapitation, the practice is common only for hybrid seed production.

Can maize survive in the environment?

Maize rarely survives outside of cultivation. It is winter-hardy only in parts of southern Europe. In addition - like the most crops - maize cannot compete with wild plants in natural environments.

See also on GMO-Compass:

• GM Plants: Maize