中国是如何在太空培育粮食作物新品种的？

A At first glance they are identical to any other ears of wheat swaying in the wind all over the world. But the vast fields of crops in north-eastern China are no ordinary plants – they were created in outer space.

乍看上去，它们与世界各地随风飘动的麦穗一模一样。然而，在中国东北这片广阔农田里生长的不是普通作物，而是在外层空间培育出来的。

They are a variety known as Luyuan 502 and are China's second most widely grown type of wheat. The plants were bred from seeds that were flown into orbit 200 miles (340km) above the Earth's surface. Here, in the unique low gravity environment and outside the protective magnetic shield of our planet, they picked up subtle changes to DNA that gave them new qualities that made them more tolerant to drought and able to better resist certain diseases.

该品种名为鲁原502，是中国种植面积第二大小麦品种。该作物是通过将种子送入距离地表200英里（340千米）的太空轨道后培育而成。在独特的微重力环境下和地球的磁场保护罩外部，作物的DNA发生了微妙变化，使它们具备了新的特征，即耐旱性更强，能够更好地抵抗某些疾病。

They are an example of a growing number of new varieties of important food crops that are being bred on spacecraft and space stations while orbiting our planet. Here they are subjected to microgravity and are bombarded by cosmic rays, which trigger the plants to mutate – a process known as space mutagenesis.

航天器和空间站在环绕地球的同时，也为重要的粮食作物培育越来越多的新品种，鲁原502是其中之一。在微重力环境下，它们受到太空辐射的轰击，诱使作物发生突变，这种现象被称为航天诱变。

While some of the mutations leave the plants unable to grow, others can be advantageous. Some become hardier and able to withstand more extreme growing conditions while others produce more food from a single plant or grow faster or require less water. When brought back to Earth, seeds from these space-bred plants undergo careful screening and further breeding to create viable versions of popular crops.

有些突变会使作物无法生长，但其他突变可能是有益的。有些作物变得适应性更强，能够适应更极端的生长环境，有些作物的单株产量增加，生长速度更快，需水量减少。太空培育的作物返回地球后，种子会被精心筛选，继续培育出常见作物的理想品种。

In a world facing increasing pressure on agriculture due to climate change and vulnerable supply chains, which have underlined the need for crops to be grown closer to where they are eaten, some researchers now believe that space-breeding, also known as space mutagenesis, may help them to adapt crops to these new challenges.

由于气候变化和脆弱的供应链，导致当今世界面临的农业压力越来越大，这表明作物的种植地有必要靠近食用地。目前有科学家认为，太空育种（也称航天诱变）也许有助于粮食作物适应这些新的挑战。

The second most planted wheat crop in China is the Luyuan 502 mutant variety that was created using space mutagenesis

中国种植面积第二大小麦作物是鲁原502突变品种，它是利用航天诱变培育出来的。

"Space mutagenesis makes beautiful mutations," says Liu Luxiang, China's leading space mutagenesis expert and director of the National Center of Space Mutagenesis for Crop Improvement at the Institute of Crop Sciences of the Chinese Academy of Agricultural Sciences in Beijing.

“航天诱变会产生美妙的突变”，刘录祥说道。他是中国航天诱变首席专家、中国北京农业科学院作物科学研究所国家农作物航天诱变技术改良中心主任。

Luyuan 502, for example, has an 11% higher yield than the standard wheat variety grown in China, a better tolerance to drought and stronger resilience against the most common wheat pests, according to the International Atomic Energy Agency, which coordinates international cooperation in the use of irradiation-based techniques for creation of new crop types.

例如，据国际原子能机构披露，鲁原502的产量比中国的普通小麦品种高11%，耐旱性更强，对于常见的小麦害虫有更强的抵抗力。国际原子能机构负责在利用辐射技术培育作物新品种方面的国际合作。
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"[Luyuan 502] is a real success story," says Liu. "It has a very high yield potential and adaptability. It can be cultivated in many different areas with different conditions."

“鲁原502取得了真正的成功”，刘录祥说道。“它的产量潜力巨大，适应力很强，可以在不同地区和不同环境下种植”。

This adaptability is what makes Luyuan 502 such a hit among farmers across China's vastly diverse agricultural landscapes and varied climate.

由于适应力很强，所以鲁原502在中国各种各样的农业环境和气候中很受农民的欢迎。

It is just one of more than 200 space-mutated crop varieties created in China over the past 30 years, according to Liu. In addition to wheat, Chinese scientists have produced space-bred rice, corn, soybeans, alfalfa, sesame, cotton, watermelons, tomatoes, sweet peppers and other types of vegetables.

据刘录祥介绍，在过去30年里，中国利用航天诱变技术培育出200多个农作物品种，鲁原502只是其中之一。除了小麦之外，中国科学家还在太空培育出水稻、玉米、大豆、苜蓿、芝麻、棉花、西瓜、西红柿、甜椒及其他蔬菜。

China has been experimenting with space mutagenesis since 1987 and is the only country in the world consistently using the technique. Since then it has conducted dozens of missions to carry crop seeds into orbit. Chinese scientists released the first space-bred crop – a type of sweet pepper called Yujiao 1 – in 1990. Compared to conventional sweet pepper varieties grown in China, Yujiao 1 produces much bigger fruit and is more resistant to diseases, says Liu.

自1987年以来，中国一直在试验航天诱变技术，世界上只有中国一直在使用这项技术。自那时起，中国开展了数十次将种子送往太空轨道的任务。1990年，中国推出第一种太空培育作物——宇椒1号甜椒。相比中国的普通甜椒品种，宇椒1号结出的果实更大，抗病能力更强，刘录祥说道。

High-energy radiation in space can trigger mutations in seeds that can lead to improved and desirable traits in important crops such as rice

太空中的高能辐射会诱使种子发生突变，使水稻等重要作物具备理想的改良特征。

China's emergence as a global space power in recent decades has enabled it to send thousands of seeds into orbit. In 2006, the country shipped into orbit their largest batch ever – more than 250kg (551lbs) worth of seeds and microorganisms of 152 species – aboard the satellite Shijian 8. In May this year, 12,000 seeds including several types of grass, oats, alfalfa and fungi, returned from a six-month visit to China's Tianhe space station as part of the crewed Shenzhou 13 mission.

近几十年来，中国崛起为全球太空大国，得以将数千粒作物种子送往太空轨道。2006年，中国利用实践8号卫星将有史以来最多的一批种子送入轨道——超过250千克（551磅）的种子和微生物，涵盖152个物种。今年5月，作为神舟十三号载人飞行任务的一部分，12000粒种子在天和空间站停留6个月后返回地球，包括多种牧草、燕麦、苜蓿、真菌。

The Chinese even sent a batch of rice seeds for a lunar round-trip with the Chang'e-5 mission that put a lander on the surface of the Moon in November 2020. According to Chinese news reports, these lunar rice seeds successfully produced grain in laboratory after their return to Earth.

2020年11月，在嫦娥五号探测器登月任务中，中国人甚至将一批水稻种子送上地月往返之旅。据中国媒体报道，这些登月的水稻种子返回地球后，在实验室里成功结出了大米。

"We benefit from China's strong space programme," Liu says. "We can use recoverable satellites, high-altitude platforms but also manned spacecraft to send our seeds to space up to twice a year and use those space utilities for crop improvement."

“我们从中国强大的航天计划中受益”，刘录祥说道。“我们可以利用返回式卫星、高空平台、载人航天器，每年两次将种子送往太空，利用航天设施对作物进行改良”。

The seeds are sent on trips lasting from just four days to several months. In this unusual environment, a number of changes can happen to seeds and plants. First, high energy solar and cosmic radiation can damage the genetic material in the seeds itself, leading to mutations or chromosomal aberrations that are passed onto future generations. The low gravity environment could also lead to other changes. Plants that germinate and are grown in microgravity show changes in cell shape and the organisation of structures within the cells themselves.

种子在太空停留的时间从四天到几个月不等。在这种特殊环境下，种子和作物会发生诸多变化。首先，高能太阳和太空辐射会破坏种子的遗传物质，继而引发突变或染色体畸变，并遗传给子代。低重力环境还会引起其他变化，在微重力环境下发芽生长的作物会出现细胞形态变化，以及细胞内部结构组织上的变化。

In most cases, Chinese scientists fly the seeds into space and then germinate them back on the ground once they are returned to Earth. The seedlings are then screened for useful traits that provide an advantage over more traditional crop varieties. The scientists are looking for changes that lead to bigger fruit, lower watering requirements, better nutrient profiles, resistance to high and low temperatures or resilience against disease. In some cases rare mutations can lead to breakthroughs in crop yield or resilience.

在大多数情况下，中国科学家将种子送往太空，返回地球后让种子在地面发芽，然后对秧苗进行筛选，寻找比传统作物品种更具优势的有益特征。科学家寻找的变化包括果实更大，需水量减少，营养素含量更优质，耐高温和低温，抗病能力。在某些情况下，罕见突变可能使作物产量或适应力有所突破。

The most promising plants are bred further, until the researchers arrive at a substantially improved variant that can address the farmers’ needs.

最有前途的植株会被进一步培育，直到科学家培育出能够满足农民需求的改良品种为止。

China, however, although currently a leader in space mutagenesis, wasn't the first nation to experiment with space-breeding. The technique dates back to some early experiments conducted by US and Soviet scientists using carrot cells launched into orbit aboard the Soviet satellite Kosmos 782.

尽管目前中国是航天诱变技术的领先者，但不是第一个试验太空育种的国家。这项技术可追溯到美国和苏联科学家开展的早期试验，他们利用苏联卫星科斯莫斯782将胡萝卜细胞送往太空轨道。

The approach relies on the same principles as nuclear mutagenesis, which has been around since the late 1920s. Nuclear mutagenesis speeds up the naturally occurring mutation processes in the DNA of living organisms by exposing them to radiation.

该方法与20世纪20年代出现的核辐射诱变原理相同。核辐射诱变是将生物体暴露在辐射中，从而加快DNA的自然突变进程。

But while nuclear mutagenesis uses gamma rays, X-rays and ion beams from terrestrial sources, space mutagenesis relies upon the bombardment by cosmic rays that pepper space around our planet. On Earth, we are protected from those high-energy rays by the Earth's magnetic field and its thick atmosphere, but in orbit, spacecraft and satellites are constantly exposed to this radiation, which mostly comes from the Sun.

核辐射诱变利用地球上的伽马射线、X射线、离子束，而航天诱变依赖于遍布地球周围的太空辐射轰击。在地球上，磁场和厚厚的大气层保护我们免受高能太空辐射的伤害，但在轨道上，航天器和卫星始种暴露在太空辐射中，其中大部分来源于太阳。

Both space and nuclear mutagenesis can help cut down the development times of new crop varieties by up to a half, according to Shoba Sivasankar, who leads the joint Plant Breeding and Genetics group of the International Atomic Energy Agency (IAEA) and the Food and Agriculture Organization of the United Nations (FAO).

联合国粮农组织和国际原子能机构（FAO/IAEA）联合部植物育种与遗传组织负责人Shoba Sivasankar表示，航天与核辐射诱变都能使作物新品种的发育时间缩减一半。
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The IAEA's nuclear laboratories in Seibersdorf, 21 miles (35km) south-east of Vienna, Austria, are the global hub and training centre for nuclear mutagenesis. Cooperating countries that don't possess their own nuclear facilities send their seeds, plant cuttings or seedlings to Sivasankar's team for irradiation.

国际原子能机构的核实验室位于维也纳东南21英里（35公里）的塞贝斯多夫，这些实验室是全球核辐射诱变中心和培训中心。如果参与合作的国家没有自己的核设施，可以将种子、植物插条、秧苗交给塞贝斯多夫的团队进行辐射。

"It only takes a couple of minutes to irradiate the seeds, but it requires sufficient knowledge and expertise," says Sivasankar. "Every variety has a different tolerance. Give the seeds a dose that is too high, keep them inside the irradiator too long, and you destroy them. They won't germinate. If you don't give them enough radiation, you won't generate enough mutations and end up with a generation that would look just like the predecessors."

“辐射种子只需几分钟，但需要知识和专业技能”，Sivasankar说道。“每个品种都有不同的耐受性。如果辐射强度过高，辐射时间过长，就会毁掉种子而无法发芽。如果辐射强度不够，就无法诱发足够的突变，结果与亲代没什么区别”。
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By sending seeds into space, Chinese scientists are trying to breed stronger crops that can produce better yields back on Earth

中国科学家将种子送往太空，努力培育出更强大的作物，使其在地球上有更高的产量。

The Joint FAO/IAEA Division of Nuclear Applications in Food and Agriculture, of which the Plant Breeding and Genetics group is a part, was founded in 1964. In the late 1920s, experiments using X-rays to induce mutations in wheat, maze, rice, oats and barley, sparked the interest of botanists all over the world. By the 1950s most developed nations had their nuclear breeding programmes, experimenting not only with X-rays but also with UV rays and gamma rays.

联合国粮农组织和国际原子能机构（FAO/IAEA）核技术粮农应用联合部成立于1964年，它是植物育种与遗传组织的所属单位。20世纪20年代，科学家在试验中利用X射线诱使小麦、玉米、水稻、燕麦、大麦发生突变，吸引了全世界植物学家的兴趣。20世纪50年代，大多数发达国家都有核辐射育种计划，除了X射线，还试验过紫外线和伽马射线。
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"At that time, there was a lot of effort in Europe and North America," says Sivasankar. "Many new varieties created with the help of nuclear mutagenesis were released. But in the past two to three decades, many of these countries abandoned the technique. Especially the US has turned to transgenic technologies that enable the insertion of pieces of foreign DNA into the genome of plants in the lab."

“当时欧洲和北美洲进行了大量努力” ，Sivasankar说道。在核辐射诱变的帮助下，许多新品种得以问世。但在过去二三十年里，其中的许多国家放弃了该技术。尤其是美国求助于转基因技术，在实验室里将外来DNA片段插入植物基因组中。

Nuclear mutagenesis, however, didn't disappear. Countries in the Asia Pacific region maintained the momentum, headed by the increasingly confident China. They continue filling the IAEA's database of mutant crop varieties, which today encompasses 3,300 newly developed crop varieties.

然而，核辐射诱变技术并没有消失。在日益自信的中国引领下，亚太各国保持了该技术的发展势头。他们在不断填充国际原子能机构（IAEA）的突变作物品种数据库，如今新培育的作物品种已达3300个。

Sivasankar says that while for some of the poorer Asian countries, the high cost of transgenic technologies may have been the primary motivation for sticking with nuclear mutagenesis, there are more practical reasons to continue using the technique mostly abandoned by the West.

Sivasankar表示，对于某些比较贫穷的亚洲国家来说，他们继续使用核辐射诱变技术的主要动因是转基因技术的高昂成本，但继续使用这种基本被西方淘汰的技术主要是基于现实因素。

"For example, the US industrial farming sector prioritises a handful of traits such as insect and herbicide resistance," says Sivasankar. "The transgenic technologies work quite well for that. But in Asian countries the situation is very different."

“例如，美国农业工业化部门优先考虑抗虫性、除草剂抗性等少数特征”，Sivasankar说道。“转基因技术在这方面效果显著，但亚洲国家的情况大不相同”。
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Asian breeders produce seeds for many small farmers who work in extremely diverse environments. Modifying just one or two traits would not be enough.

亚洲育种企业生产的种子供应给许多小农户，他们的耕种环境千差万别，仅仅改良一两个特征是不够的。

"They need more complex traits, many of them related to the climate situation such as heat and drought tolerance or the ability to grow in nutrient-poor or saline soil," says Sivasankar. "That, in my opinion, cannot be achieved with transgenic technologies."

“他们需要更复杂的特征，其中许多与气候环境有关，例如耐高温、耐旱性、在贫瘠土壤或盐碱土壤中生长的能力，Sivasankar说道。“我认为转基因技术做不到这些”。

China sees the effort to improve the genetic pool of its agriculture crops as a necessity. According to Liu and his team the world has to increase its production of vital cereals by 70% if it wants to feed an additional two billion people that are expected to live on the planet by 2050. The growing population in the Asia Pacific region is at the highest risk of suffering from food shortages, they say.

中国认为改进农业作物的基因库是必要的。刘录祥及其团队表示，要想养活2050年预计新增的20亿人口，关键谷物的产量必须增加70%。不断增长的亚太地区人口面临粮食短缺的风险最高，他们说道。

Through nuclear and space mutagenesis, China alone has developed and introduced over 800 new varieties, improving on all key characteristics compared to the original crops, according to the IAEA.

国际原子能机构的资料显示，通过核辐射和航天诱变技术，仅中国就培育和推行了800多个新品种，与原生作物相比改进了所有的关键特征。

But one questions remains: what is the advantage of sending seeds to space when the same can be done in labs on the ground?

但还有一个问题：如果地面实验室能取得同样的效果，那么将种子送往太空有什么优势？

Liu admits that sending seeds to space costs more than sticking them into ground-based irradiators. Still, the space trips seem to provide clear benefits and frequently produce more interesting results.

刘录祥承认，将种子送往太空比使用地面辐射装置更昂贵，但太空旅行能带来显著的益处，取得的成果往往更有吸引力。

"We actually see a higher frequency of useful mutations from space mutagenesis than from gamma rays," says Liu. "In space, the radiation intensity is considerably lower, but the seeds are exposed to it over a much longer period of time. What we call the linear energy transmission of the particles and the overall biological effect are higher in space and there is a much lower rate of damage to the seeds compared to those irradiated in labs."

“我们确实发现，航天诱变比伽马射线更容易产生有用的突变”，刘录祥说道。“太空中的辐射强度低得多，但种子暴露其中的时间更久。在太空中，粒子的线性能量传输和整体生物效应更高，种子的受损率远低于实验室里辐射的种子”。
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In an irradiator, the seeds receive large doses of ionising – from 50-400 grays – over a period of a few seconds, says Liu. On the other hand, seeds on a weeklong space trip are exposed to only two milligrays. As a result, up to 50% of seeds don't survive the harsh ground-based treatment while almost all of the seeds flown in space usually germinate, he adds.

在辐射装置里，种子受到大量的电离辐射——50-400戈瑞——几秒钟内，刘录祥说道。而在为期一周的太空之旅中，种子受到的辐射只有2毫戈瑞。因此，高达50%的种子无法在苛刻的地面辐射中存活，而几乎所有被送往太空的种子都能发芽，他补充道。

"All these techniques are very useful and are helping us solve some very real problems," says Liu. "There are too few opportunities to fly seeds to space. We can't rely only on that."

“这些技术非常实用，帮助我们解决某些实际问题”，刘录祥说道。“将种子送往太空的机会太少了，我们不能只依靠这种方式”。

Nasa has been growing lettuce on the International Space Station in experiments it hopes will lead to fresh food for astronauts

美国航空航天局一直在国际空间站开展种植莴苣的实验，希望让宇航员吃上新鲜事物。

Now it appears there is renewed interest from other parts of the world in growing food in space. In November 2020, American commercial space services company NanoRacks announced plans to operate orbiting greenhouses. Their goal? To develop new crop varieties that would be better suited to feed the world as it faces worsening climate change.

目前看来，世界其他地区对太空培育粮食重新产生了兴趣。2020年11月，美国商业航天服务公司纳型支架（NanoRacks）公布了运营“轨道温室”计划，他们的目标？在世界面临日益严峻的气候变化之际，研发出更适合养活世界的农作物新品种。
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For the endeavour, the company, known for dispatching small satellites from the International Space Station, partnered with the United Arab Emirates, a country with little arable land of its own, meaning it has to import much of the food it requires.

为此，纳型支架（NanoRacks）公司与阿联酋展开合作。该公司以从国际空间站发射小型卫星而著称，阿联酋的耕地面积少，这意味着大部分所需粮食只能依靠进口。

However, not all seeds return from space as fledgling super plants. A batch of lettuce seeds sent to the International Space Station by European scientists in 2020 grew slower after their return to Earth when compared to plants that had stayed on the ground.

然而，并非所有从太空返回的种子都会变成新的超级作物。2020年，欧洲科学家将一批莴苣种子送往国际空间站，但返回地球后，生长速度比地球的原生莴苣更慢。

Much of the research now being conducted on growing food while in space is aimed at helping astronauts feed themselves while on missions. Astronauts on the ISS, for example, have been harvesting romaine lettuce since 2015 and eating it, and a study published in 2020 found it was safe to eat, and could provide a valuable source of nutrients on long missions.

目前开展的许多研究都是针对粮食作物的，而太空培育作物旨在帮助宇航员在执行任务中自给自足。例如：自2015年以来，国际空间站上的宇航员一直在收获和食用长叶莴苣。2020年公布的一份研究报告显示，这些作物吃起来很安全，可以给执行长期任务的宇航员提供宝贵的营养来源。
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But while growing food for astronauts could prove invaluable as space agencies around the world set their sights on returning humans to the Moon and visiting other planets such as Mars, space food will perhaps be of even greater use to those of us who remain here on Earth.

随着世界各地的航天机构着眼于人类重返月球和造访火星等其他行星，为宇航员种植粮食可能是极其宝贵的，但太空粮食作物对于我们这些地球居民来说可能更有用处。