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On September 17th, 1998 the Ithaca Journal ran its first "Ask A Scientist!" article in which Professor Neil Ashcroft , who was then the director of CCMR, answered the question "What is Jupiter made of?" Since then, we have received over 1,000 questions from students and adults from all over the world. Select questions are answered weekly and published in the Ithaca Journal and on our web site. "Ask A Scientist!" reaches more than 21,000 Central New York residents through the Ithaca Journal and countless others around the world throught the "Ask a Scientist!" web site.

Across disciplines and across the state, from Nobel Prize winning scientist David Lee to notable science education advocate Bill Nye, researchers and scientists have been called on to respond to these questions. For more than seven years, kids - and a few adults - have been submitting their queries to find out the answer to life's everyday questions.

Previous Week's Question Published: 25 January, 2006 Next Week's Question
Electric shock in plants produces impulse that could stunt growth
Question
How will electric shocks to a plant effect its growth?

Question
A lightning strike is the most extreme form of an electric shock to a plant. It has sufficient energy to split tree trunks by heating the water in the trunk so that it vaporizes at high pressure. The effects of small electric shocks (or "stimulations") are more difficult to observe and have not been widely studied even though interest in plants and electricity goes back over a century to the pioneering studies of the English physiologist John Scott Burdon-Sanderson and the Indian physicist J.C. Bose.

One way in which mild electric shocks may influence plant growth is by the production of "action potentials" in plant cells. Action potentials are reversible changes in the electrical voltage between the inside and the outside of cells that travel long distances along cell membranes. These miniscule electrical signals are widely used to regulate rapid processes in the cells of all organisms from the cells of giant algae to the brain cells of Albert Einstein. They are commonly known as "nerve impulses" when they occur in the nerve cells of animals. The rapid movements that occur in insectivorous plants, such as the Venus' fly trap or the sundew, or in the sensitive plant Mimosa, are usually produced as a result of mechanical stimulation that triggers an action potential. However, the action potentials can also be triggered by electric shocks. There is disagreement about whether the movement occurs due to growth of some of the plant cells or whether it simply involves a change in cell shape resulting from a change in pressure inside the cells.

More recently, it has been shown that many plants can transmit action potentials in the phloem tissue. The phloem consists of cells used to transport sugars and other nutrients from leaves to places where growth is taking place. Furthermore, it has been shown that the action potentials can inhibit the export of nutrients from the leaves via the phloem. It has also been shown that action potentials can cause a temporary inhibition of photosynthesis, the process in which light is used to convert carbon dioxide from the air into sugars. So it appears that electric shocks may inhibit plant growth by interfering with the normal production and distribution of the chemicals used to support growth, possibly by interacting with a signaling system that is involved in the normal control of growth in plants.