If plants generate magnetic fields, they're not sayin'

April 7, 2011
A titan arum nicknamed "Trudy" is fully opened after flowering in June 2009 in the UC Botanical Garden. Two sensors of a magnetomer are visible to the lower left. Credit: Eric Corsini, UC Berkeley

Searching for magnetic fields produced by plants may sound as wacky as trying to prove the existence of telekinesis or extrasensory perception, but physicists at the University of California, Berkeley, are seriously looking for biomagnetism in plants using some of the most sensitive magnetic detectors available.

In an article that appeared this week in the , ('Search for plant biomagnetism with a sensitive atomic magnetometer', J. Appl. Phys. 109, 074701), the UC Berkeley scientists describe the instruments they used to look for minuscule magnetic fields around a – the world's largest flower – during its brief bloom, the interference from local BART trains and traffic that bedeviled the experiment, and their ultimate failure to detect a magnetic field.

They established, however, that the plant generated no magnetic field greater than a millionth the strength of the magnetic field surrounding us here on Earth.

Why look for biomagnetism in ?

"There is a lot of activity now by scientists studying biomagnetism in animals, but not in plants," said Dmitry Budker, UC Berkeley professor of physics. "It is an obvious gap in science right now."

In animals, for example, activity in the heart and brain produce tiny magnetic fields that can be measured by sensitive magnetometers.

"We feel like this is a first step in an interesting direction that we would like to pursue," he added.

Budker spends most of his time developing extremely sensitive magnetic field detectors – in particular, atomic magnetometers based on nonlinear magnetooptical rotation (NMOR). These devices can measure magnetic fields as low as 10 femtotesla, nearly a billion times lower than Earth's magnetic field at the surface, which is usually between 20 and 50 microtesla, depending on the location.

Magnetic noise in the laboratory initially led the Budker team to the University of California Botanical Garden, which provided an isolated space for them to test their magnetometers. There, the researchers, including graduate student Eric Corsini, encountered the garden's famed titan arum (Amorphophallus titanium), a plant that every few years sends up a tall, thick stalk covered with thousands of small flowers enveloped by one large, flower-like calyx. During its brief flowering, the plant gives off a powerful odor of rotting flesh to attract the carrion beetles and flesh flies that pollinate it.

"This giant, skirt-like thing opens fairly quickly, over an hour or two, and the plant starts to heat up and get really warm, and then gives off this odor that is strongest for the first 12 hours," said Paul Licht, director of the UC Botanical Garden. "By the end of 24 hours, all the real action is over; the pollination cycle has a very brief window to succeed."

Because magnetic fields are created by moving electrical charges, such as a current of electrons, the researchers thought that rapid processes in the plant during the rapid heating might involve flowing ions that would create a magnetic field. In the titan arum, the rapid heating raises the plant temperature as high as 20 to 30 Celsius (70-85 degrees Fahrenheit).

"In principle, there shouldn't be a fundamental difference between animals and plants in this respect, but as for which plants might produce the highest magnetic fields, that is a question for biologists," Budker said.

In June 2009, one of the garden's arums was ready to erupt, so the Budker group, headed by Corsini, set up a sensitive, commercial magnetometer next to the plant in a hothouse and monitored it continually. During the day, visitors entering the hothouse generated magnetic signals, and the BART trains several miles away created .05 microtesla signals periodically.

"We were most disappointed in not being able to put a tighter tolerance on our measurement, because we couldn't find a way to cancel out the local ambient noise," Corsini said.

He and Budker expect that they can increase their sensitivity by a factor of 10 or 100, however.

"We haven't given up," Corsini said. "The next step is to see whether we can get hold of a smaller plant and perhaps shield it from outside magnetic fields far from public viewing. So far, biomagnetism is a fun side project for me, but if we were to see something …."

"The hope is that, next time one flowers, we're going to get it," Licht said.

People who want their own titan arum can purchase offspring, some now three to four feet high, at the botanical garden. While these plants make fascinating and easy houseplants, however, the owner should be prepared to move out of the house for a night when the plant ultimately flowers, Licht said.

Explore further: Hold your nose and head for the hills: Titania is opening

More information: Search for plant biomagnetism with a sensitive atomic magnetometer, J. Appl. Phys. 109, 074701 (2011); doi:10.1063/1.3560920

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not rated yet Apr 07, 2011
Sigh. The article's headline and caption are the type of crap that keeps Physorg from being the serious rival to ScienceDaily's or Digg's fluff. Why is it wacky to search for biomagnetism in plants? You'd think we'd expect it. Obviously these scientists did. Any EMF may be weak, even incredibly weak, but if there is any sort of electrical activity there you'd expect something. The article even says:

"'We were most disappointed in not being able to put a tighter tolerance on our measurement, because we couldn't find a way to cancel out the local ambient magnetic field noise,' Corsini said."

It's almost certainly there, however small.
1 / 5 (1) Apr 07, 2011
Uhm. It is common sense that if chemical reactions produce magnetic fields (which they do) that all living organism produce magnetic fields(however weak they are)...

Hell, even a wooden table or a rock produces a very small amount magnetic fields.
not rated yet Apr 07, 2011
If salts or ions are being transported in a transpiration stream, there should be an electric field produced. Given that magnetic fields are a vector of an electric field, the magnetic field should be proportional to the electrical field produced. So maybe there is not enough fluid movement in the plant to detect an electric field.
There are electrical potentials in photosynthesis and respiration. It may just be that the composition of plant fluids are not the same as animal fluids that may have an impact on the magnitude of the electrical field.
1 / 5 (2) Apr 07, 2011
Optimistically believing in the high intrinsic efficiency of natural processes, I think the detection range of instrumentation in this case, compounded by extraneous noise-signals and lack of effective shielding, just put the target signals out of range. Apart from fluidic/suspended particulate stream transports any biochemical activity or molecular dynamics will develop magnetic signals by underlying electron exchange. In rough association with "plant signals," does anyone remember the Baxter experiments with polygraphs attached to philodendrons while brine shrimp were dumped into boiling water by a random interval generator?
4 / 5 (1) Apr 07, 2011
I've seen demonstrations on nanotechnology where researchers were able to trick bacteria, due to their biomagnetism, and the fact that the bacteria use magnetism to guide themselves. With the help of a nano-scale computer chip, which generated a small, controllable magnetic field, the researchers were able to "control" the bacteria and trick it into swimming in the direction they wanted to go.

So biomagnetism is a real phenomenon with real world potential applications.
4.5 / 5 (2) Apr 08, 2011
this is so silly - magnetic field can be produced only by ferromagnetic materials and currents. presumably there are no ferrous materials in the plant, but thats an easy check, leaving just the magnetism produced by currents - which must be there, they're fundamental.
so why not measure the currents? - they will be very small ionic currents - and, since there can be no nett current flow they will be in the form of small loops.
if one were to assume the xylem and phloem (??) channels were to carry the ion currents up and down there would be a very small multipolar magnetic field - it would drop fiercely with distance given the very small distance separation. One could do an order of magnitude calculation, femtoteslas or much less i would say.
3.7 / 5 (3) Apr 08, 2011

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