植物与电的不解之缘：给植物通电能促进生长吗？

In the 19th Century, a handful of scientists were gripped with a strange obsession – that electricity might be harnessed to make plants grow better. Could they have been on to something?

在19世纪，少数科学家有个奇怪的嗜好——利用电流可能使植物长得更好。他们发现了什么线索吗？

There's a good chance you're familiar with Frankenstein's monster. But have you heard about his garden?

你很可能熟知弗兰肯斯坦的怪物，但你听说过他的花园吗？

Around the time the scientist who inspired Mary Shelley's novel Frankenstein was busy electrocuting live animals and dead prisoners, several of his contemporaries were doing the same to perennials and root vegetables. And just as these 18th Century forays into electrical stimulation purported to make the human body more robust (by delivering it from maladies ranging from paralysis and depression to diarrhoea and venereal disease), they were also being investigated for the betterment of plant life. Experiments on electrified gardens were alleged to produce a range of benefits, from brighter flowers to tastier fruit. Before long, this pursuit went the way of its cousin, medical electro-quackery, and by the end of the 19th Century, respectable science had largely jettisoned both.

玛丽·雪莱的小说《弗兰肯斯坦》的灵感来自一位科学家，当他忙于用电刑处死活体动物和死囚犯的时候，几个同时代人正在对多年生植物和根茎类蔬菜做同样的事情。正如18世纪旨在强身健体的电刺激试验一样（治愈瘫痪、抑郁、腹泻、性病等疾病），人们也在研究电刺激给植物带来的益处。据说电气园艺试验带来了许多益处，包括花朵更鲜艳，水果更鲜美。没过多久，这种尝试就走上了它的近亲——电子庸医之路。到了19世纪末，可敬的科学基本上把两者都淘汰了。
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More than a century on, better tools and new insights are reanimating the study of electricity's effects on biology. Uninformed early animal experiments have resolved over the past 200 years into real understanding – and led to promising electrical medicine. Similarly, the old vegetable experiments are being exhumed to see what modern fruit they may yield. Maybe the new understanding could even improve 21st Century gardens.

一个多世纪后出现了更好的工具和新的见解，关于电流对植物的生理影响方面的研究重新活跃起来。在过去的200年里，古老而蒙昧的动物实验已逐渐演变为真知灼见，产生了富有前景的电疗。同样，科学家也在探索古老的植物试验，看看可以取得什么现代成果。新的认识甚至可能给21世纪的园艺带来进步。

The first hints that electric shocks might have a dramatic impact on crops came not from any human intervention but from nature itself. After a lightning storm, according to longstanding Japanese farming lore, mushrooms would proliferate madly.

电击可能对农作物产生巨大的影响，最初的线索并非来自人为干预，而是来自大自然。根据日本流传已久的农业传说，雷雨过后，蘑菇数量激增。

But you couldn't exactly call down lightning on demand to confirm this experimentally. Until, that is, the 1740s when various new devices allowed scientists to store and deploy this still-mysterious phenomena of "electricity" at will for the first time.

但你在试验中不可能随时召唤闪电来验证这种现象。直到18世纪40年代涌现出各种新型设备，科学家第一次可以随意地储存和利用这种仍然神秘的“电”现象。

Soon deploying electricity as a gardening aid became a hot topic. Pierre Bertholon de Saint-Lazare – a French physicist and philosopher who experimented widely on the still poorly understood mysteries of electricity – curated many of his contemporaries' plant experiments into a collection, De L'électricité des Végétaux.

很快，利用电流作为栽培的辅助手段成为一个热门话题。皮埃尔·贝尔托隆·德·圣拉扎尔是一位法国物理学家和哲学家，他对人类仍然知之甚少的电奥秘进行了广泛的试验，将同时代人的许多植物试验编纂成了文集《植物通电》。

Alongside the brighter blossoms, flowers were alleged to bloom earlier after electrification; similarly, electrifying fruit reportedly hastened the ripeness of their smell and taste. But Bertholon's main focus was on the new device he had invented: instead of zapping individual fruits and vegetables one by one, the huge contraption could infuse electricity into entire garden plots. It electrified the very soil and air that nurtured the growing plants – as if it was an electrical "manure".

通电后不仅花开得更鲜艳，据说还会提前盛开；同样，据报道给水果通电能加快气味和味道的成熟。但贝尔托隆的重点是他发明的新式装置：这座巨大而奇特的装置能给整个园地通电，而不是电击单个的水果和蔬菜。该装置能给栽培植物的土壤和空气通电，犹如电气“肥料”。

The electro-vegeto-meter

植物通电仪

The elevated system of masts and wiring Bertholon had rigged up collected atmospheric electricity, drew it down, and distributed it into his crops. According to him, it mimicked the stimulating effects of lightning. Only it did the job better than the natural variety, dispensing small, continuous amounts of electricity rather than dosing with a single, damaging strike. The "electro-vegeto-meter", he reported, increased the growth of the plants beneath its arc, accelerating "the germination, the growth, and production of leaves, flowers, fruit, and their multiplication".

贝尔托隆利用桅杆和电线搭建成简易的高架装置，用来收集大气电流，将电流引下来分配给农作物。据他说这能效仿闪电的刺激作用，但比大自然的效果更好，提供小而持续的电流，而不是一次破坏性的打击。他的报告显示，“植物通电仪”提供的电流促进了植物生长，加速了“叶子、花朵、果实的萌发、生长、繁殖”。

Bertholon also made copious use of electricity in other forms, reportedly dispatching insect pests by using a rudimentary tool to zap an infested tree. His contemporaries had many other colourful uses for electricity in their gardens – one set out plans to irrigate his plants with a special water that he claimed, rather dubiously, had been "impregnated with electrical fluid" to replace traditional approaches to fertiliser.

贝尔托隆还以其他方式大量利用电流，据说使用一种简易工具电击遭受虫害的树木来杀死害虫。他的同时代人在园艺中对电流有许多其他丰富多彩的用途——有个人打算用一种特殊的水灌溉植物，相当可疑的是，他声称水中“充满了电流体”，用于替代传统的施肥方法。

Not everyone was convinced. Things went badly after Jan Ingenhousz, the Dutch-British physiologist who discovered photosynthesis, availed himself of an electro-vegeto-meter of his own to use on his garden – and it promptly shrivelled up all his plants. He concluded that Bertholon's electrical manure was, well, manure.

并不是所有人都坚信不疑。发现光合作用的荷兰裔英国生理学家简·英根豪斯在自己的花园里使用一台植物通电仪，结果情况不妙，所有的植物立刻枯萎了。他得出的结论是，贝尔托隆的“电气肥料”其实是粪肥。

Interest in electroculture waned. A few private gentleman scientist types continued to run small experiments: in the 1830s, one claimed his experiments demonstrated that plants are excellent conductors, implying that electricity was a fundamental aspect of their biology. But neither the science nor tools were sufficiently advanced to support such claims. After that, apart from a few niche projects, the idea of electroculture swiftly fell out of favour among the electrorati.

人们对电气栽培逐渐失去兴趣。少数自掏腰包的绅士科学家继续进行小型试验：19世纪30年代，有个人声称他的试验证明了植物是良好的导体，这表明电流是植物的基本机理因素。但当时的科学和工具都不够先进，不足以支持这种说法。后来除了一些小众项目，电气栽培这种理念很快就失宠了。

"We cannot avoid asking ourselves," wrote two critics in a plaintive 1918 paper, looking back on the fall of the events, "how it is that while the study of electricity and its many industrial applications has developed into enormous importance, electroculture in the meantime has remained practically stationary for a century and a half." They concluded: "We probably find the answer in the stagnation of the science of the living plant."

“我们不禁自问”，两位评论家在1918年的一篇论文中哀叹道，回顾这些事件的发生，“电气研究及其许多工业用途已经变得极其重要，为什么电气栽培却在一个半世纪里几乎停滞不前”？他们的结论是：“我们也许能从活体植物学的发展停滞中找到答案”。

In other words, to improve electroculture you'd first have to understand how it might work, and to understand that, one would need to understand the electrical dimensions of plant biology. Luckily, by the time the duo voiced their complaint, the first slim shoots of exactly such an endeavour were already poking through the frost. Interest in vegetation and electricity had been reanimated by none other than Charles Darwin.

也就是说，要想改进电气栽培，你先得了解工作原理，要想做到这一点，你需要了解植物生理的电特性。可喜的是，两位评论家发出抱怨的时候，做这种尝试的首批萌芽已经从霜冻中破土而出。使人们重新对植物与电产生兴趣的正是查尔斯·达尔文。

Darwin's carnivorous vegetables

达尔文的食肉植物

His grandfather had been convinced that electricity could hasten the growth of plants – but Charles Darwin's contention was built on more solid scientific ground. He believed electricity to be a fundamental aspect of plant physiology, the same way the neurophysiologists of the 19th Century were starting to show how electric signals are the fundamental underpinning of the human nervous system signals that let us to think and feel and move.

他的祖父相信电流能够促进植物的生长，但查尔斯·达尔文的观点是基于更可靠的科学依据。他认为电流是植物生理上的基本要素，正如19世纪的神经生理学家证明，电信号是人类神经系统信号的基础，使我们得以思考、感知、活动。

Darwin's obsession had started small, with a single meat-eating plant in the genus Drosera, otherwise known as the sundews. Barely a year after the publication of On the Origin of the Species, it was all he could think about. "At the present moment, I care more about Drosera than the origin of all the species in the world," he wrote in 1860. Little wonder. Drosera did everything plants aren't supposed to – it ate meat, and it hunted. Its long, sticky tentacles trapped flies on glue-like secretions and then curled inexorably around the unfortunate prey until it was wrapped up like a macabre Swiss roll.

达尔文的痴迷始于一种不起眼的食肉植物，它属于茅膏菜属植物，又名毛毡苔。《物种起源》出版仅仅一年之后，他满脑子想的都是这种植物。“现在我更关心的是茅膏菜属植物，而不是世界上所有物种的起源”，他在1860年写道。这也难怪，茅膏菜属植物所做的一切都是植物不该做的——吃肉和捕捉猎物。又长又粘的触毛把苍蝇困在胶水一样的分泌物里，然后触毛在不幸的猎物四周卷曲，直到被裹得像一个恐怖的瑞士卷。
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Darwin was intrigued by the animal-like reflexes of the Venus flytrap

让达尔文感兴趣的是，捕蝇草有像动物一样的本能反应。

How could this be? "Carnivorous vegetable" was an oxymoron! But Drosera wasn't alone. Dionaea muscipula (you know it as the Venus flytrap) hunted even faster – as Darwin admiringly described, "the leaves of which catch insects just like a steel rat-trap". Their reflexes seemed animal-like. One friend, a physiologist and botanist whose expertise straddled the plant and animal kingdoms, suggested they examine these odd plants for the same kinds of "nervous" electrical changes that physiologists had recently identified animating animal muscles.

这怎么可能呢？“食肉植物”是矛盾的说法！但茅膏菜属植物并非独有，捕蝇草（Dionaea muscipula）的捕捉速度更快——正如达尔文钦佩地描述道：“它们捕虫的叶子犹如钢制捕鼠器”。它们的本能反应就像动物。一位朋友是生理学家和植物学家，他的专业知识横跨植物界和动物界，他建议检查这些奇特植物的“神经”电位变化，最近生理学家发现这种电位变化使动物肌肉变得兴奋。

They found them. The published results showed that when the flytrap slammed shut, it was accompanied by activity that looked awfully similar to the action potential that had defined animal electricity. These signals were not unique to the animal kingdom.

他们找到了电位变化。公布的结果显示，当捕蝇草猛然合拢时，伴随的活动与决定动物电流的动作电位极其相似，这些电信号并非动物界所独有。
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But their ideas, too, were overwhelmingly rejected by plant physiologists. You can understand why: carnivorous plants moved fast and hunted like animals – so for them, nervous signals made a kind of sense. But other plants didn't move, and they didn't hunt. They just sat there and ate sunshine. It made no sense to them to extrapolate the unique attributes of the carnivore – a taxonomic outlier – to the rest of the plant kingdom.

但是，他们的观点也遭到了大多数植物生理学家的反对。你可以理解其中的原因：食肉植物的动作很快，像动物一样捕捉猎物——所以神经信号对它们来说是有意义的。但其他植物既不活动，也不捕捉猎物，只是静止地摄取阳光。推断植物界的其他植物也具有食肉植物（分类系统中的另类）的独特特征毫无意义。

A couple of decades later, an Indian engineer and polymath called Jagadis Chandra Bose revisited Darwin's question. He was particularly curious about Mimosa pudica, a little fern-like perennial. It doesn't eat meat – but it does move. It folds up its little fern leaves when startled – a remarkable tic that has earned it a slew of nicknames over the years, including "sensitive plant" and touch-me-not. Bose reckoned that these fast movements should be underpinned by animal-like nervous activity too.

几十年后，一位名叫贾加迪斯·钱德拉·博斯的印度工程师和博学家重新审视了达尔文的问题。他对含羞草特别好奇，它是一种有点像蕨类植物的多年生植物。它不吃肉——但确实会动。受到惊吓时，它会把小小的蕨叶合拢起来——这钟奇特的抽搐多年来为它赢得了许多绰号，包括“敏感植物”、“不要碰我”。博斯认为，这种快速动作应该也是基于动物一样的神经活动。

Sure enough, an electrometer revealed the action potentials he was looking for, spiking right before the little plant folded up its leaflets, just as they had been found preceding the snap-shut response of the Venus flytrap. Bose's curiosity was inflamed: what other plants had electric signals? In 1901, he reported strong electrical signals in a slew of ordinary plants that neither moved nor ate, including rhubarb and horse radish. Over the next decades these findings were extended to onions, trees, and pretty much every member of the plant kingdom anyone bothered to measure.

果然，就在这株小植物合拢叶片之前，静电计显示他寻找的动作电位急速上升，就像在捕蝇草猛然合拢之前发现的那样。这激起了博斯的好奇心：还有哪些植物有电信号？1901年，他报告了许多既不活动也不捕食的普通植物也有强烈的电信号，包括大黄和马萝卜。在接下来的几十年里，这些发现扩展到了洋葱、树木，以及植物界里几乎每一种有人愿意测量的植物。

Plants are electric

植物是带电的

This went largely unexplained until the late 20th century, when neuroscience tools revealed that plant cells use electrical charges to manage their internal communications, just as animal cells do. All living cells have pores in their outer lining which ensure that different ions stay on different sides of the membrane. Mammalian cells like to keep potassium ions inside and sodium ions outside. As a result of these imbalances, the inside of the cell carries a tiny negative charge. The nervous system uses these little batteries to send all messages about what the body is feeling and doing to and from the brain.

这在当时基本无法解释，直到20世纪末，神经科学的工具揭示了植物细胞和动物细胞一样，利用电荷来实现体内通信。所有活细胞的外层都有孔隙，可以确保细胞膜的两侧存在各种离子。哺乳动物的细胞喜欢把钾离子留在内侧，把钠离子留在外侧，这种浓度差导致细胞内携带微小的负电荷。神经系统利用这些小电池与大脑交流关于身体感受和行为的所有信息。

Plant cells have an inner voltage too, and they use them to the same effect: to communicate information about their environment. Research conducted in the late 1990s demonstrated that plants responded electrically to different stimuli, including light, temperature, touch, and injury. This aligned with insights from chemical plant communication, which suggested that plants can sense danger, communicate with other plants and call to animals for help. Corn, for example, can summon wasps to attack the kinds of caterpillars that attack corn. During those decades, concepts that had previously only been associated with neuroscience increasingly crept into plant physiology.

植物细胞的内部也有电压，它们利用电压来达到同样的效果：交流有关环境的信息。20世纪90年代末进行的研究表明，植物对各种刺激都会产生电流反应，包括光、温度、触摸、伤害。这与植物化学通讯的见解相一致，后者表明植物可以感知危险，与其他植物进行通讯，并向动物寻求帮助。例如，当玉米受到毛虫的攻击时，它会召唤黄蜂来进行反击。在那几十年里，以前只与神经科学相关的理念越来越多地渗透到植物生理学中。

Towards the end of the 19th century, an Indian scientist found electrical signals in Mimosa pudica, otherwise known as the 'sensitive plant'

19世纪末，一位印度科学家在含羞草中发现了电信号。

Such findings reignited a decades-old conversation about plant intelligence, perceived as an irrelevant wild goose chase in some circles of plant electrophysiology. Are plants intelligent? If so, what would it say about our definition of "intelligence"? The debate continues, but it is not the only way to think about plant electrical signals.

这些发现再次激起了几十年来关于植物智能的讨论，植物电生理学的某些圈子认为，植物智能是一个没什么用处和虚无缥缈的课题。植物有智能吗？如果有的话，对于我们有关“智能”的定义意味着什么？争论仍在继续，但这并不是思考植物电信号的唯一方法。

Some botanists are not averse to the idea that plants use complicated signals to communicate with each other and the natural world. It's just that they are not like ours. In animals, electrical communication works like this: nerve cells like to keep potassium inside and sodium outside, and the electrical differences created by these ions' separation fundamentally underpins the neuron's ability to send an action potential. However, sodium plays no part in plant action potentials, because sodium is toxic to plants. In their bodies, the roles of potassium and sodium are played by potassium, chloride, and calcium. The electrical signals this enables look different, on closer inspection. For one thing they are stronger. For another they have a slightly more varied repertoire. Apart from the standard action potential, plants also enlist two further signals - the "variation potential" and the "system potential".

有些植物学家并不反对这种观点，即植物利用复杂的信号来与彼此以及自然界进行通讯，但与我们的信号有差别。在动物界，电通讯的原理是这样的：神经细胞喜欢把钾离子留在细胞内，把钠离子留在细胞外，离子的相互隔离产生了电位差，基本构成了神经细胞发送动作电位能力的基础。但是，钠离子在植物的动作电位中不发挥作用，因为钠对植物有毒。在植物体内，钾和钠的作用由钾、氯化物、钙来代替。经过仔细观察，以这种方式产生的电信号似乎有所不同。一方面信号更强；另一方面，信号具备的能力稍多一些。除了普通的动作电位，植物还能发送另外两种信号——“变异电位”和“系统电位”。

These signals coordinate different systems. The action potential basically acts like it does in animals: communicates quickly and over long distances, about interesting stimuli, for example someone touching it or a palpable temperature change. The variation potential is more variable (as the name suggests); it's triggered by cutting, burning, and other kinds of injury, and the size of the signal depends on the severity of the damage. The surface potential is slow and local and probably lixed to nutrient status.

这些信号协调植物的各个系统。动作电位的作用基本和动物一样：就值得关注的刺激因素进行快速、远程的通讯，比如受到触摸或明显的温度变化。变异电位顾名思义比较易变；它由切割、烧伤及其他类型的伤害触发，信号大小取决于受伤的严重程度。表面电位具有缓慢和局部性特点，并且可能与营养状况有关。

But plants don't just use these signals to talk to themselves about their internal state: they may also be talking to one another. Some believe they can travel through a network of fungal filaments that are ubiquitous in soil and appear to act as circuitry.

但是，植物不仅利用这些信号与自己交流体内的状态：植物之间也可能进行交流。有人认为，信号可以通过真菌丝网络进行传播，真菌丝在土壤中无处不在，它们似乎发挥着电路的作用。

This has raised a new prospect. Could we eavesdrop on plants, and decode these electrical signals ourselves? From knowing whether the plants are sitting comfortably – are they too hot or cold? Do they need more nutrients from the soil? Or could they give us an early warning that our plants are being attacked by pathogens?

这开辟了新的前景。我们能否窃听植物和破译这些电信号？了解植物是否感觉舒适——是否太热或者太冷？它们需要从土壤中摄取更多的养分吗？它们能否向我们发出预警：我们的植物正在遭受病原体的攻击？

It raises a tantalising prospect – we may be about to find out what our vegetables are "thinking".

这开辟了诱人的前景——也许我们即将知道植物在“想”什么。