![Technician holds alfalfa plant with its 14-foot long roots exposed. Link to photo information](/peth04/20041031211548im_/http://ars.usda.gov/is/graphics/photos/jul02/k9926-1i.jpg) Alfalfa can have
long roots and is one of 22 plant species found to develop adventitious roots
in clusters along older roots. Here, a technician holds a greenhouse-grown
alfalfa plant with roots 14 feet long. Click the image for more information
about it. |
Plant Roots, Too, Know How to "Seize the
Moment" By Don
Comis March 30, 2004
A recent discovery by Agricultural Research Service plant
physiologist Richard Zobel may lead to a "rewriting of the book" on plant
roots. Zobel and a colleague have found that many plant roots commonly regrow
from the same spot on a root, and that they can do this on roots deep below the
soil surface.
Zobel, with the ARS Appalachian Farming Systems Research
Center in Beaver, W.Va., and Dominick J. Paolillo, Jr., at
Cornell University in Ithaca, N.Y., found
evidence of roots growing this way on 22 species of plants from 12 different
plant families in nine orders of plants. These plants included alfalfa,
carrots, chicory, clover, crown vetch, dandelion, horse chestnut,
lamb's-quarters, parsnip, poke weed, rock maple, thistle and tree of heaven.
Zobel and Paolillo made these discoveries while searching for
plants with so-called opportunistic, or adventitious, rooting. They found
adventitious roots growing in clusters along older roots. Adventitious roots
grow from a different cell layer than the regular, lateral roots, so a plant
that has used up the tissue available to grow regular roots can still grow
adventitious roots.
These roots are called "opportunistic" because they can develop
in a matter of hours, to take advantage of sudden environmental changes such as
a rare rain in a desert.
The discovery that adventitious roots growing this way are an
everyday occurrence suggests they may play an important and unexpected role in
routinely helping plants reach water and nutrients. These roots can sprout on
larger roots whose lateral roots have long since died back, enabling the plant
to access water and nutrients that have recently become available in those
sections of the soil that would otherwise be out of reach.
This information could also help scientists introduce
adventitious roots to a crop like cotton that apparently is one of the few
plants that doesn't have them, as a more efficient way for the crop to grow new
roots when rain comes after a dry spell.
ARS is the U.S. Department of
Agriculture's chief scientific research agency. |