Agriculture Reference
In-Depth Information
The way this works is there are some plants that have cells with imbalanced charge
distributions on them. These are known as “polar cells”. Cells of this type tend to have a
collection ofsimilarelectric chargesononlyonesideoftheircellular membranecompared
to non-polar cells that more or less have a balanced charge all around them.
Polar vs Non-Polar Cells
Source: Universiteit Gent: Liquid Crystal & Photonics Group
They can be found on regular roots as well as root hairs. So, depending upon the species of
plant, its root hairs may have a tendency to grow either towards or away from the positive
source of the electric field. For example, plants that have roots that tend to grow towards
the positive electrode include Vicia, Zea, Secale, Hordeum, Cannabis, Ricinus, Cucurbita,
Tropaeolum, Convolvulus, Cynaria, Helianthus , and others 1 2 .
One of the major contributors to the discovery of these behaviors was Andrew
Goldsworthy in collaboration with his colleagues Minas Mina and K.S. Rathore. With
Mina, by measuring minute amounts of electrical current that flow into and out of plant
cells,theyobservedthatthecellsofsomeplantrootsarepolar.Whatthismeansisthatthey
haveapreferencethathasthemrespondingtoanelectric fieldbygrowinginoneparticular
orientation. For example, if the field was oriented north-south, the portion of root cells
called the callus would orient themselves along that axis, with one side of the cell being
closer to the north. They also foundout that these cells can be effectively 're-programmed'
when stronger electric fields were applied to cells in the opposite direction 3 .
In addition to affecting the direction of growth, Goldsworthy and Rathore found that for
some plants, the flow of current in one direction through the plant (e.g. roots to leaves)
stimulated growth while flow in the opposite direction inhibited it. Consider the results as
described in an April 9, 1985 New York Times article covering the research:
“Theresearchworkers,K.S.RathoreandA.Goldsworthyofthecollege'sdepartment
of pure and applied biology, applied direct current of about a millionth of an ampere
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