In the wild they eat seeds from thistles, dandelions, sunflowers, and ragweed.

而在野外，它吃蓟，蒲公英，向日葵和豚草的种子。

And if you have allergies, ragweed is a bad plant.

如果你出现过敏，那豚草就坏植物。

Increased carbon dioxide in the air may also lead to ragweed pollen that is stronger, or more allergenic.

空气中二氧化碳增多还可以使豚草花粉变得，具过敏性。

Ragweed is a common allergen, especially during the fall.

豚草一种常见的过敏原，秋天时尤为常见。

They found that ragweed plants produced much more pollen when carbon dioxide levels increased.

他发现，二氧化碳浓度增加时，豚草产生了多花粉。

Ziska said that ragweed is one of the plants that has the most effect on human health.

杰斯卡表示，豚草类健康影响最大的植物之一。

Many farmers control pigweed and other problem plants by growing genetically modified crops.

许多农民通过种植转基因作物来控制豚草和其他问题植物。

Springtime, which is tree pollen, summertime, which is grass pollen, and ragweed, which is fall.

春天树木花粉的季节，夏天草类花粉的季节，而豚草则主宰着秋季。

The researchers grew ragweed in a controlled environment and increased the carbon dioxide levels in the air.

研究员在受控环境中种植了豚草，同时增加了空气中的二氧化碳浓度。

Worse yet, sumpweed is a wind-pollinated relative of ragweed, the notorious hayfever-causing plant.

糟糕的，甘草豚草的风媒近亲，豚草臭名昭著的引起花粉症的植物。

Like ragweed's, sumpweed's pollen can cause hayfever where the plant occurs in abundant stands.

与豚草一样，松草的花粉会引起花粉症，植物生长在丰富的林分中。

So you have trees coexisting with grass and now you have grass with actual ragweed and molds.

因此，你会有树木与草共存，现在又有了草与真正的豚草和霉菌共生的情况。

So let's take ragweed, for example.

以豚草为例。

And one of the plants that has a(n) effect in terms of human health is ragweed. It's the most common allergen in the fall.

而类健康有影响的其中一种植物就豚草。豚草秋天最为常见的过敏原。"

He and another USDA researcher, Frances Caulfield, looked at the effects that rising carbon dioxide levels were having on the production of ragweed pollen.

他和美国农业部研究员弗朗西斯·考菲尔德研究了上升的二氧化碳水平豚草花粉产量的影响。

FALL IS IN THE AIR AND SO IS LARGE AMOUNTS OF RAGWEED WHICH CAN BE ESPECIALLY DANGEROUS FOR THOSE LIVING WITH ASTHMA.

秋天到了，空气中弥漫着大量的豚草，这哮喘患者尤其危险。

One study done in Europe estimates that by 2050, airborne ragweed pollen concentrations could be about four times higher than they are right now.

一项在欧洲进行的研究估计， 到2050年，空气中豚草花粉的浓度可能比现在高出约四倍。