Plants Make Sounds When Stressed

植物压力大也会“说话”

Take care of your plants！ They may “scream” if you treat them badly. Although this is an exaggeration， plants can make sounds when they are stressed， according to a paper published in Cell.

“Plants interact with insects and other animals all the time， and many of these organisms use sound for communication， so it would be very suboptimal for plants not to use sound at all，” Lilach Hadany， co-author of the study， told Science Focus.

With this in mind， the research team started by recording plants sounds. They placed tobacco and tomato plants in soundproof boxes to shut off the noise in the environment. Several ultrasonic microphones were then put near the plants， which can record at frequencies between 20 and 250 kilohertz. The maximum frequency that a human adults ear can hear is about 16 kilohertz.

爱护你的植物吧！如果不好好侍弄你的植物，它们可能会“尖叫”。虽然“尖叫”是一种夸张的说法，但发表在《细胞》杂志上的一篇论文指出，植物在受到压力时也会发出声音。

论文合著者Lilach Hadany在接受《科学焦点》杂志采访时表示：“植物一直在与昆虫和其他动物互动，其中许多生物之间都用声音交流，所以对植物来说，完全不发出声音是非常不利于交流的。”

考虑到植物会用声音交流，研究团队开始记录植物的声音。研究人员将烟草和番茄植株置于隔音箱中，隔绝环境中的噪声，然后将几个超声波麦克风放在植物附近。这些麦克风可以捕捉频率为20千赫至250千赫的超声波，而成年人能听到的最高频率约为16千赫。

There were three groups of plants： One group wasnt watered for five days， another group had the stems cut off and the last group was untouched. The microphones caught sounds at a frequency of 40 to 80 kilohertz from the first two groups.

The sound， which was similar to the noise of popcorn popping when “translated” into a frequency humans can hear， grew louder and louder during the five days of water stress. They then began to decline as the plants dried out. A stressed plant produced the popping sound around 30 to 50 times per hour， while the untouched group only produced around once per hour， according to the study.

The researchers havent yet discovered how the sounds are made. One theory is that they could be made during cavitation， which is a process of an air bubble in the plant collapsing under some kind of pressure.

After the experiment， the team gathered the data on stressed plants and then made machine-learning software that could tell how plants “feel”. It could differentiate between unstressed plants， thirsty plants and cut plants， which can be useful for farmers in monitoring the conditions of their crops.

研究人员放置了三组植物：一组植物五天沒有浇水，另一组植物的茎被剪掉，最后一组植物则保持了原状。据前两组的麦克风录音显示，这些植物发出了频率在40千赫至80千赫的声音。

将植物发出的声音“转译”为人类能听到的频率，会听到一种类似于爆米花爆裂的声音，而在缺水的五天里，爆裂声变得越来越大。然后，随着植物干枯，声音开始变小。研究表明，一株受到压力的植物每小时发出大约30至50次爆裂声，而未受到压力的植物每小时只发出约一次声音。

研究人员尚未发现这些声音是如何产生的。有一种理论认为，声音可能是因发生气穴现象而产生，该现象是指植物中的气泡在某种压力下破裂的过程。

实验结束后，研究团队收集了受到压力的植物的数据，而后开发了机器算法软件，用以识别植物的“感觉”。该软件可以区分未受到压力的植物、缺水的植物和受损的植物，因此对农户监测作物的生长状况大有助益。

Word Bank

soundproof /'sa?ndpru?f/ adj. 隔音的

differentiate /'d?f?'ren?ie?t/ v. 区分；辨别

Its difficult to differentiate between the two varieties.