必克VOA新闻：科学家发现蒲公英或能代替橡胶树
必克VOA新闻，每日一听，竖起你的耳朵，倾听世界的声音！ 小编与您共努力！ Rubber May Soon Come From Dandelions Synthetic rubber has been around for more than a century, but quality tires for cars, trucks and aircraft still need up to 40 percent or more natural rubber content. As the source of natural rubber, the rubber tree, is prone to disease and can be affected by bad weather. So scientists are looking for replacements may have found one in a ubiquitous weed. Rubber trees, growing mostly on Southeast Asian plantations, are sensitive plants - giving the optimal yield of raw rubber only under ideal atmospheric conditions, an equal distribution of rainfall and bright sunshine, with the absence of strong winds. They are also extremely sensitive to a plant disease that has devastated rubber plantations in the tree’s original habitat, South America. Dandelions, on the other hand, are tough weeds, that grow, even in poor soil, and are not overly sensitive to a changing climate. Scientists have long known that the dandelion's milky sap contains latex, the main ingredient of raw rubber. A variety native to Kazakhstan is the richest source. Researchers at Germany’s Fraunhofer Institute for Molecular Biology and Applied Ecology, supported by car tire industry, are trying to manipulate its genes to produce latex in quantities suitable for commercial exploitation, says lead researcher Dirk Pruefer. “One of the main challenges in dandelion research was to produce plants, novel plants that have an improved rubber content that has a good economic behavior in the field. And that is why we're working since years [for] years on the breeding program to develop new traits in the plants, stabilized traits - for example stable rubber content," said Pruefer. The genetically-engineered dandelion is already producing half a ton of rubber per hectare, but Pruefer says the scientists’ goal is about twice as much. They would also like to grow taller plants with upright leaves, which are more suitable for machine harvesting. Pruefer says one of the leading tire manufacturers, Continental AG, is already testing tires made with dandelion-based rubber. “They made a lot of testing tissues so see the quality of the material. And what you can see is that the quality is similar to that what they have originally done with the rubber from the rubber tree," he said. Researchers say large fields in Europe and Asia, currently unusable due to poor soil, may someday be covered with rubber-producing yellow flowers. See more information, you can visit us 英语口语测试 http://www.spiiker.com/daily/
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