Truffles are coveted as a delicacy and difficult to grow. Photo: Thomas Wanhoff, cc-by-sa license
Read out For decades, fewer and fewer truffles are found in the forests. In return, artificially created truffle plantations increase. But breeding the coveted mushrooms is still a difficult business. Scientists are now looking for the success factors for perfect breeding of the coveted tubers. Titoune had almost lost his appetite for truffle hunting. The bitch trudged reluctantly with the researchers Alexander Urban and Tony Pla through the truffle plantation near Vienna. But when the owners of the system come to the baggage, Titoune was again fully in the thing. The bitch crisscrossed the grounds and headed straight for one of the tree hazel. A direct hit. Minutes later, the researchers are digging out a small burgundy truffle in the roots of the man-sized tree. It is the first harvest on an Austrian truffle plantation - a sensation for Urban.

For ten years now, the mushroom researcher at the University of Vienna has been all about underground growing tubers. From the beginning he was eager to find out whether it is possible in the Alpine region, too, as is the tradition in Italy and France: the breeding of expensive fruiting bodies. In 2004 he founded the company Trüffelgarten with the French forestryer Tony Pla, which has since been selling trees whose roots are inoculated with spores of the local Burgundian truffles. Plantations can be set up with the plants so prepared. After five to ten years, the first truffles should grow in the soil, Urban promises.

Buyers have also found themselves in Germany. In Bavaria, in the German wine growing regions, even in Berlin and on the North Sea one is interested in the truffle trees. In his garden, the Bavarian painter Ingo Fritsch is already harvesting the precious mushrooms, in order to lure gourmets and art lovers into his studio.

For the time being, however, the founders of the company must let it go. The plantation is still too young to search Titoune again. However, Urban already hopes for a peak crop of up to 300 kilograms per hectare per year. With 200 to 300 euros per kilogram sales value mushrooms would be a lucrative commodity. display

A considerable proportion of the precious tubers in the Mediterranean have long come from plantations. In France, more than 80 percent of the expensive Périgord truffles are artificially propagated. In oak groves, they thrive in their roots.

But although the delicate mushrooms can now breed, the effort is still very large, says historian Rengenier Rittersma of the University of Saarland: "Artificial plants are still the second choice today. Regions where the truffles are naturally occurring are far more productive. "

The fungus reacts highly sensitive to its environment. Soil, light, moisture, animals and plants - every little thing must be right so that he can even gain a foothold. The fungal threads then sprout into the root cells of oak or tree hazel trees, with which the truffle lives in symbiosis.

But the cooperation between mushroom and tree is shaky. The fact is: For some inexplicable reason, truffles often do not sprout despite togetherness. About the causes puzzle the scientists until today. At their natural sites, they discovered an astonishingly high genetic diversity and now believe that it is a key to success. Mice, wild boars and deer are likely to help carry truffle spoils for miles by eating the tubers and excreting the spores with the faeces. Urban is currently following this phenomenon. Maybe one day there will be integrated plantation management involving animals, he speculates.

In the meantime, the best harvests are being driven to areas where wild truffles used to be found. The superiority of the natural distribution areas for breeding has made historian Rittersma a popular man today. As a consultant to the European Interest Group of Truffle Seekers and Breeders he is to derive from old records, where the tubers could thrive today.

But even in their natural ecosystem, the truffles turn out to be moody mushrooms. "If you start a plantation for black perigord truffles, you can sometimes find only winter truffles in the soil. These are worth much less and have a very intense, but rather obtrusive taste, "Urban describes typical problems. The fact that another mushroom is harvested than spent is often due to the underground competition: The soil can harbor spores of low-grade species, which prevail if they are only slightly better adapted to the location. Sometimes it happens that the harvested truffle changes from one year to the next. "Of course, this is a nightmare for the farmers, especially since production never returns to its original form, " says Rittersma.

The alleged escapades of the tubers show only how little man understands them. Not all species are known so far. "It started from a little over twenty in Europe. But we suspect that there are more, most of which are not of culinary interest, "says Urban.

Meanwhile, time is running out for researchers. Because the tubers in the soil disappear dramatically. "For seven to eight decades fewer and fewer wild truffles have been found, " reports Rittersma. In France alone, the harvest has plunged from more than 1, 000 tons in the late 19th century to less than 100 tons. This is partly due to the massive exploitation by Tr ffelj ger. On the other hand, climate change is putting the pearls of the earth on the map. Summers are getting increasingly hotter in the Mediterranean, and the snow is not coming out. As a result, the soil is moistened worse. The spores can not grow. Rittersma is convinced: "The Truffle can only be saved if its ecologic potential is finally perceived."

ddp / science.de - Susanne Donner

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