短文
Carbon dioxide is a potent greenhouse gas. Levels of carbon dioxide, or CO2, in the atmosphere are increasing at an unprecedented rate. But what impact do higher CO2 levels have on plants? Plants use CO2 from the air along with sunlight and water to produce carbohydrates they use for energy. This process is called photosynthesis. Higher atmospheric CO2 increases the rate of photosynthesis, and thus the amount of carbohydrates in plant leaves. Sounds beneficial, right? However, scientists have found that as CO2 levels go up, plant defenses might go down. Researchers at the University of Illinois used a special open-air research facility that allowed them to grow soybean plants in different concentrations of CO2—without changing other factors such as sunlight, insects or rainfall. They discovered that soybeans grown in fields with higher CO2 levels had much more insect damage and attracted more adult insect pests than those in plots with less CO2 in the air. The insects might have been attracted by the higher carbohydrate levels in the leaves of plants grown in high CO2. But a higher carb diet wasn’t the only thing that encouraged infestation. Normally, soybean plants under attack by insects will produce jasmonic acid. This inhibits the insects’ ability to digest leaves, which protects the plant from further attack. In high CO2 atmospheres, the plants were unable to produce this defensive chemical. So, the dangers of rapidly increasing CO2 in our atmosphere might extend beyond climate change. Since soybeans grown at higher CO2 would lose a crucial defense pathway and attract more hungry beetles, other food crops might also be more vulnerable if CO2 levels continue to rise.
二氧化碳是一种强力的温室气体。 大气中的二氧化碳的浓度正在以前所未有的速度增长。但是空发中高浓度的二氧化碳对植物有什么样的影响呢？ 植物运用空气中的二氧化碳，与阳光、水一起产生能量所需的碳水化合物。这个过程叫做光合作用。 二氧化碳浓度较高的大气增加了光合作用的速率，因此植物中碳水化合物的数量就会过剩。听起来很有利，对吧？然而科学家们发现随着二氧化碳浓度的升高，植物的防御将会降低。 伊利诺伊大学的研究人员采用了特殊的露天研究设施，这些设施可以使他们在不同浓度的二氧化碳中种植大豆植物-不用改变其他的因素，如阳光，昆虫，或者雨水。 他们发现在较高浓度二氧化碳中种植的大豆会遭受更严重的虫害，与在空气中二氧化碳浓度较低的地方相比，它们会吸引更多的成年害虫。 这些昆虫被植物叶子中由高浓度的二氧化碳产生的高含量的碳水化合物所吸引。但是高碳水化合物的饮食并不是引起虫害的唯一原因。 一般来说，被昆虫攻击的大豆植物都会产生抑制昆虫消化叶子能力的茉莉酸，以保护植物免受进一步的损害。在高二氧化碳环境中，植物无法产生这种防御性化学物质。 所以二氧化碳急速增长所带来的危害可能远远不止气候变化。既然在高二氧化碳环境中种植的大豆会失去防御的关键通道并引来更多饥饿的甲虫，如果二氧化碳浓度继续升高的话，其它粮食作物可能也会变得更加脆弱。