
Root System Regulates Whole Plant GrowthBy Hank Becker March
30, 1998Plants speed up or slow down their growth in response to signals about the
soil environment that are sent by the roots to the shoots. Plant physiologists have uncovered increasing evidence that root tips launch
these signals--in the form of hormones and other chemicals--to inform shoots and
leaves about the soil's water, nutrient supplies, hardness and temperature, say
Agricultural Research Servicescientists. ARS biophysicist Robert M. Aiken and colleagues at ARS'
Great Plains Systems
Research Unit in Fort Collins, Colo., analyzed growth patterns of corn root
systems. He attributed changes in the distribution and architecture of the
roots to chemical activity of the tips, the sites of cell division. These
changes may increase or decrease the volume of soil accessible to the roots for
taking up water and nutrients. Growing root tips are uniquely positioned to serve many sensory and
signaling functions. Plant physiologists have been uncovering increasing evidence that plant
roots chemically signal shoots about soil conditions like hardness and
temperature. Signals include nitrate--a plant nutrient--and hormones including
cytokinins and abscisic acid, believed to regulate growth and development of
shoots and roots. The shoot responds in two chief ways. Production of enzymes used in
photosynthesis slows down or speeds up. Leaf pores enlarge or shrink, also
influencing photosynthesis. These responses, in turn, further modify the
shoot's nitrogen demand, photosynthesis rate and water use. Ultimately, researchers hope the information can help farmers better control
pests and diseases while reducing the effects of environmental stresses such as
drought on crops. The strategy would involve interpreting soil and plant data
obtained by precision farming technologies such as remote sensing and yield
monitors on combines. Scientific contact: Robert M. Aiken, Central Great Plains Research,
Akron, CO, 80720 phone (970)345-0519, fax (970) 345-2088,
[email protected]. Story contacts Great Plains Systems Research U.S. Department of Agriculture | |