Form Approved
REPORT DOCUMENTATION PAGE
OMB No. 0704-0188
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1. AGENCY USE ONLY (Leave blank)
2. REPORT DATE
3. REPORT TYPE AND DATES COVERED
May 1996
4. TITLE AND SUBTITLE
5. FUNDING NUMBERS
Soil Physical Environment and Root Growth in Northern Climates
SERDP 712-94
6. AUTHORS
Gurdarshan S. Brar and Charles M. Reynolds
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)
8. PERFORMING ORGANIZATION
REPORT NUMBER
U.S. Army Cold Regions Research and Engineering Laboratory
72 Lyme Road
Special Report 96-13
Hanover, New Hampshire 03755-1290
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)
10. SPONSORING/MONITORING
AGENCY REPORT NUMBER
11. SUPPLEMENTARY NOTES
For conversion of SI units to non-SI units of measurement consult Standard Practice for Use of the International System of Units (SI),
ASTM Standard E380-93, published by the American Society for Testing and Materials, 1916 Race St., Philadelphia, Pa. 19103.
12a. DISTRIBUTION/AVAILABILITY STATEMENT
12b. DISTRIBUTION CODE
Approved for public release; distribution is unlimited.
Available from NTIS, Springfield, Virginia 22161.
13. ABSTRACT (Maximum 200 words)
Understanding the growth and function of plant roots in cold climates is critical, but examination of root sys-
tems to elucidate their link to production is expensive and labor-intensive. Limited information is available
on the root growth and functions of plants grown in northern climates. Our objective is to present an over-
view of the influence of physical edaphic factors on plant root systems with special emphasis on models that
are available for simulating root growth. This report summarizes the impact of the soil physical environment
(soil water, soil temperature, soil air, physical impedance, and spatial variability) on root uptake and growth.
Roots grow because new cells are formed in the meristematic tissue near the root tip, and these newly
formed cells increase in volume, pushing the root tip forward if growth conditions are satisfactory. Rapid
elongation of primary roots, combined with well-developed secondary roots, allows the plants to exploit
moisture and nutrients from a greater soil volume. Root and shoots are strongly interdependent. The roots
receive photosynthates and growth hormones from shoots and in return furnish water and nutrients to the
shoots. Several root growth models have been developed during the past decade; however, none addresses
the problems associated with cold regions. The models reported in the literature can be classified as 1) sim-
ple models, 2) carbon partition models, 3) growing degree day-based models, 4) soil parameter-based mod-
els, and 5) arctic plant growth models.
14. SUBJECT TERMS
15. NUMBER OF PAGES
Root system
Water uptake
28
Physical environment Soil temperature
16. PRICE CODE
Root growth models
Spatial variability
17. SECURITY CLASSIFICATION
18. SECURITY CLASSIFICATION
19. SECURITY CLASSIFICATION
20. LIMITATION OF ABSTRACT
OF REPORT
OF THIS PAGE
OF ABSTRACT
UNCLASSIFIED
UNCLASSIFIED
UNCLASSIFIED
UL
Standard Form 298 (Rev. 2-89)
NSN 7540-01-280-5500
Prescribed by ANSI Std. Z39-18
298-102
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