爲什麼新割的草那麼好聞？
Why Does Freshly Cut Grass Smell So Nice?
爲什麼新割的草那麼好聞
If you grew up in the suburbs, you recognize it immediately: the sweet, sharp smell of someone mowing a lawn or ballfield. As it wafts into your nostrils, it somehow manages to smell exactly like the color green. But what are we really smelling when we inhale that fresh-cut grass scent? And why do we like it so much?
如果你是在郊區長大的，你立刻就能聞出這個味道——剛修剪完草坪或棒球場後甜美、濃烈的氣味。當它飄進你的鼻孔時，它的味道不知爲何如綠色般清新。不過，當我們吸入新割的草的氣味時，我們真正聞到的是什麼呢？爲什麼我們這麼喜歡這個味道？
Chemically speaking, that classic lawn smell is an airborne mix of carbon-based compounds called green leaf volatiles, or GLVs. Plants often release these molecules when damaged by insects, infections or mechanical forces — like a lawn mower.
從化學角度來講，這種典型的草坪氣味來源於空氣中混合的碳基化合物，稱爲綠葉揮發物（簡稱GLVs）。植物在受到昆蟲、傳染病的入侵或機械外力如割草機的破壞時，會釋放這些分子。
Plants manufacture slightly different forms of GLVs depending on what's happening to them, said Ian Baldwin, a plant ecologist and founding director of the Max Planck Institute for Chemical Ecology in Jena, Germany. In a 2010 study published in the journal Science, he and colleague Silke Allmann, of the University of Amsterdam, found that tobacco leaves punctured and rubbed with insect saliva released a different bouquet of volatile compounds than leaves that had been poked and brushed with water.
植物生態學家、德國耶拿馬克斯普朗克化學生態學研究所創始所長Ian Baldwin說，植物製造的GLVs會根據它們所遭遇的不同入侵而略有不同。在2010年發表於《科學》雜誌上的一項研究中，他和阿姆斯特丹大學同事Silke Allmann發現，被昆蟲侵食和唾液摩擦的菸葉釋放出的揮發物，與被水沖刷過後所釋放的揮發物不同。
GLVs are small enough to take to the air and float into our nostrils. In some cases, they can be detected more than a mile from the plant where they originated. Other species, such as insects that eat plants and the predators that eat those insects, are extremely sensitive to different GLV aromas. For instance, Baldwin and Allmann discovered that predatory Geocoris bugs are attracted to the GLVs released by plants chewed on by a pest called the tobacco hornworm. In other words, the specific smell of the besieged plants indicates to the predators that a snack is nearby.
GLVs很小，它們混雜在空氣中，飄進我們的鼻孔。某些時候，在離其原產植物一英里以外的地方就能聞到。像食草昆蟲以及吃這些昆蟲的捕食者等物種，它們對不同的GLV氣味非常敏感。例如，Baldwin和Allmann發現，一種名爲菸草天蛾的害蟲啃食植物後，植物釋放出的GLV會吸引有益的昆蟲捕食者大眼蟲，也就是說，被圍困的植物釋放的特殊氣味向捕食者發出了附近有它們的食物的信號。
