BMELV coexistence research programme 2006

"It is still too early for concrete statements about minimum distances."

The Federal Ministry of Food, Agriculture and Consumer Protection (BMELV) is continuing the experiments into coexistence between various agricultural systems with and without genetic engineering that it began in 2005. This year trial fields have been set up at six locations. As in 2005, the focus is on pollen drift and incrossing rates in maize. The aim of the multi-year research programme is to derive minimum distances between fields with genetically modified and conventional maize. – GMO Safety spoke to Gerhard Rühl of the Federal Agricultural Research Centre (FAL), who coordinates the programme.

Dr. Gerhard Rühl (FAL, Federal Agricultural Research Centre) in Braunschweig coordinates the BMELV research programme on ensuring the coexistence of GM and GM-free agriculture.

Intermediate area with cereal: On the trial site in Braunschweig there is barley between the maize plots. By the time the maize pollen starts drifting, the barley will have been harvested and the areas between the maize fields will be covered with stubble.

White maize test system: This test system is designed to measure outcrossing events without using genetically modified maize. The pollen donor is common yellow maize. The recipient is a special white maize (top photo). Incrossing events from yellow maize can be seen in individual yellow grains on the white maize cobs (bottom photo). However, white maize and yellow maize have different flowering habits, so this test system cannot produce exact values.

GMO Safety: The BMELV is continuing the coexistence research programme that it started in 2005. What research questions are being investigated in 2006?

Gerhard Rühl: This year one important aspect is the derivation of minimum distances between genetically modified and genetically unmodified maize. Here we are interested in what level of incrossing we can expect with increasing distance from the GM maize plot in the prevailing wind direction.

We are conducting all the experiments under worst-case scenario conditions, i.e. conditions under which the highest levels of outcrossing can be expected. All the trial plots are located downwind. In addition, we are using a donor (Bt maize ) variety and a recipient (conventional maize) variety that flower at the same time. When the male and female flowers open at the same time, this is ideal for incrossing.

GMO Safety: Is it just about the distances at which considerable outcrossing can be expected?

Gerhard Rühl: We also want to find out whether the crop planted between the GM and non-GM maize affects the pollen drift and the incrossing rates. This year we are testing two crops – a clover/grass mix and cereal stubble. This is to take account of the high incidence of cereals in crop rotations.

This year we are also testing the effectiveness of a maize cordon. We have sown this only on the side of the GM maize plot facing the conventional maize.

In one location we also want to investigate the impact of the drill direction. Last year’s trials indicated that it could make a difference to outcrossing rates whether the maize rows are planted in the wind direction or at ninety degrees to it.

GMO Safety: You are using two test systems – Bt maize and non-GM white maize hybrids. Why is that?

Gerhard Rühl: The best system for the exact calculation of minimum distances is one that consists of Bt maize and the relevant isogenic variety. The aim, after all, is to determine at which minimum distances the legal threshold of 0.9 per cent can be respected in practice. With the Bt maize and isogenic hybrid system we can measure outcrossings quantitatively.

In addition, we are using a ‘GM-free’ test system. That’s the white maize. We count the number of yellow grains on a white maize cob and this gives us an idea of the incrossing rate. Last year, however, we discovered that exact measurements are not possible with this system. It provides qualitative findings – whether there have been more or fewer incrossing events. We are therefore using the white maize for comparative studies into e.g. the impact of the crop between the maize fields and the drill direction.

GMO Safety: What were the results of the 2005 trials?

Gerhard Rühl: Since these are the results of a one-year trial, we are being very cautious about making statements about minimum distances. Agronomic trials should normally last at least three years.

Last year we had only two sites for studying incrossing rates under farm-like conditions: Groß-Lüsewitz and Wendhausen. We measured very different incrossing rates on these two sites. Compared with the literature they were relatively high. But they tie in with the higher incrossing rates that were found in the cultivation trials in 2005. We found incrossing rates above 0.9 percent even at a distance of 78 metres at the edge of a conventional maize plot.

GMO Safety: What impact did the crop between the maize plots have on pollen drift and incrossing rates in 2005?

Gerhard Rühl: Last year we tested sunflowers and a clover/grass mix on the areas between the maize fields. We were surprised to find that the tall sunflowers did not act as a physical protection and did not result in lower incrossing rates. The different thermals over low-growing crops like clover/grass and cereal stubble therefore appear to have a greater bearing on pollen drift.

GMO Safety: What recommendations can you currently make for farming practice based on your experiments? The ministry (BMELV) reported at the beginning of the month that a distance of 150 metres is necessary when cultivating GM maize to be on the safe side with coexistence.

Gerhard Rühl: There is no point trying to establish reliable minimum distances at the moment because of the lack of data. More concrete statements will be possible only once this year’s trials have been evaluated. The 150m minimum distance suggested by the ministry is not based on data from our experiments last year. Our working group had previously recommended a distance of 50 metres based on the literature studies.

GMO Safety: Last year there were also agro-biodiversity trials.

Gerhard Rühl: The biodiversity research is not being continued in 2006.

"It is still too early for concrete statements about minimum distances."

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