plants and polygraphs

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Offline niclas

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plants and polygraphs
« on: 17/08/2006 18:23:54 »
when i was younger i was given a book called 1,500 fascinating facts. i was already familiar with a lot of the facts in the book but one always bothered me and since i did not have the internet all those years ago i decided just to forget about it. i recently read the book again and found the annoying fact so here i am with my fact to see if the naked scientists or any forum users could make sense of it. i do not have the book with me at the moment so i can't give any names or editions etc but i will post those details when i return to university.

the book states that a plant hooked up to a polygraph machine responded to the death of animals in the room it was situated in. the plant responded, as expected, to watering and light changes but also to the death of prawns (possibly shrimps) in the room it was in. the researcher had a piece of apparatus that dropped single live prawns into boiling water at random intervals. from the polygraph results it was clear that the plant was responding to the death of the prawns. the researcher then placed a few dead prawns in with the live ones waiting to be dropped into the boiling water and discovered that the the plant would not respond to a dead prawn being dropped into the boiling water. the plant was only responding to live prawns being killed.
the next observation was after another researcher uprooted a different plant in the same room. after this event the plant would respond to the researcher who uprooted the plant as he entered the room. the plant would only respond to this one person, not to any of the other rearchers who had not uprooted plants.

to the best of my knowledge the book is not published by an extremely reputable company but the vast majority of facts in it are factual. i find the plant on a polygraph machine fact hard to believe and would be extremely grateful if you could shed some light on it for me. how could a plant remember specific people/events or tell if something had died around it?

i download your podcasts and the amount of time i've spent listening to them since discovering you worries me a little. i have got my girlfriend hooked and also introduced you to many colleagues who enjoy the show lots too. well done on a fantastic show; keep it up.

niclas roberts, 20 years old, southampton.


even a stopped clock gives the right time twice a day
even a stopped clock gives the right time twice a day



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Re: plants and polygraphs
« Reply #1 on: 22/08/2006 15:05:51 »
Plants do make "popping" noises which can be picked up by a sensitive microphone:-

"  As the water is pulled up the tree the water column puts up a resistance, much like stretching a rubber band.  Just like a rubber band will snap  if pulled too hard, so too will a water column break or cavitate.  This occurs because the reduced pressures in the water column cause gases to come out of solution and form a vapor lock in that cell.  Cavitation can be heard by placing a sensitive microphone on the plant. Tiny popping noises can be heard, a little like a bowl of rice krispies. "

Environmental factors like humidity and carbon-dioxide concentration, would change this rate of "popping".
Placing a tank of water (with prawns) near the plant would increase humidity, decomposing (dead) prawns would produce carbon-dioxide.
Human breath has high levels of carbon-dioxide, so there is some truth to the saying that "talking" to plants makes them grow faster, (talking = increased exposure to carbon-dioxide from breath).
« Last Edit: 22/08/2006 15:09:25 by ROBERT »