01.02.2008

Advanced greenhouse for climate experiments with plants

The RERAF greenhouse has just been rebuilt, which now makes it possible to control all parameters relevant to climate experiments with plants. The six unique climate chambers at Risø DTU are currently being used for an experiment to uncover what happens with the genes when plants adapt to new climatic conditions.

RERAF – Risø Environmental Risk Assessment Facility – was built in 1995 as a risk assessment facility for i.a. controlled experiments involving poisonous gases and genetically modified plants. However, a year ago it was decided to rebuild and convert the facility, so that it would be possible to experiment with climate change.

RERAF comprises six 24-square-metre climate chambers with a height of three metres each, which in itself is a remarkable size. Another feature that makes RERAF unique is the ability to add gases such as ozone.

“Ozone occurs naturally in the air but is rarely a part of the climate in such chambers. And since it is to some extent harmful to plants, it is really important that we can also control ozone levels to get a realistic picture,” says project manager Teis Nørgaard Mikkelsen.

Wind turbines have also been installed in the new RERAF, which can regularly blow the plants about a bit to stimulate natural root growth.

Furthermore, it is possible to adjust the light intensity and “day length” using 42 powerful lamps in each chamber while at the same time adding more CO2, and finally it is, of course, possible to control the air humidity.

All the parameters are controlled via a monitoring system that allows the scientists to create completely different scenarios in the six chambers.

“RERAF has entered the premier league of greenhouses, and it is going to attract many students and scientists from all over the world,” says Teis Mikkelsen, who has already taken on a PhD student from Germany, a student writing his dissertation and several project students.

Plants adapt, but how?
Senior scientist Rikke Bagger Jørgensen is heading an experiment with rape and barley which is currently being conducted at RERAF. The purpose of the experiment is to see how the species evolve over several generations when many climatic factors change at the same time. Normally, experiments with climate change only run for a single generation and usually involve only one or a maximum of two climatic parameters. However, the results will be much more realistic if you can study all factors at the same time – closely mimicking nature.

Crop plants have been chosen over natural plants because the scientists have a good understanding of crop genetics.

“We have different types of rape and barley – some old ones that are very diverse and newer ones which are more highly bred and therefore less diverse. We have also included both a Nordic and a southern variant of each,” says Rikke Bagger Jørgensen. “At the same time, we have a small “model species”, Arabidopsis, because it has a very short reproduction cycle.”

The scientists are hoping to find out whether there is a natural selection of the plants (and thereby the genes) that do best in a hot climate with spells of drought and increased CO2 and ozone concentrations, or whether the plants adapt to the changes by altering their genetic make-up.

If it turns out that only plants with the optimum genetic make-up for this particular climate survive, it could, afterall, be fatal if in future we see completely different, quicker climate changes with which the plants cannot keep up. Then it will be even more important to store the old cultivars in gene banks.

The chambers are bustling with activity. The plants are counted and observed, the trolleys on which the pots are standing are turned three times a week, and every week they are wheeled into a new chamber, allowing for any minor climatic variations in the chambers.

The rape plants are tall and erect, while many of the barley plants are flopped over the edge of the pots and have brown spots on the leaves. However, this does not give any immediate indication of the potential yield. Both the yield and the biomass will be examined concurrently with the actual molecular research being conducted into the plants’ genetic make-up.

RERAF = Risø Environmental Risk Assessment Facility

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Teis Nørgaard Mikkelsen
Senior Scientist
Biosystems (BIO)
Dir tel+45 46774162