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Diurnal changes in net uptake rate of nitrate are associated with changes in estimated export of carbohydrates to rootsThe rate of NO3- uptake by soybean (Glycine max [L.] Merrill) roots generally declines during the night in association with progressive depletion of the nonstructural carbohydrate pool in the shoot as well as the concentration of carbohydrates in roots. To determine if NO3- uptake rate changes in response to variations in translocation rate of carbohydrates from shoot to roots per se or to carbohydrate status of the roots, the night period was interrupted with a low light level from incandescent lamps to alter the diurnal pattern of NO3- uptake by roots and export of carbohydrate from shoots of nonnodulated soybean. Depletion of NO3- from replenished, complete nutrient solutions containing 1 mM NO3- was measured by ion chromatography and rates of NO3- uptake were calculated. Changes in export of carbohydrates from shoot to roots during intervals of the night period were calculated as the differences between rates of disappearance in contents of nonstructural carbohydrates and their estimated rates of utilization in shoot respiration and growth. A positive, significant correlation occurred between changes in calculated rates of carbohydrate export from shoots and NO3- uptake rates. Conversely, there was no significant correlation between concentrations of nonstructural carbohydrates in roots and NO3- uptake rates. These results support the hypothesis that carbohydrate flux from shoot to roots has a direct role in regulation of nitrogen uptake by the whole plant.
Document ID
20040121744
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Rideout, J. W.
(North Carolina State University Raleigh 27695-7619, United States)
Raper, C. D. Jr
Raper CD, J. r.
Date Acquired
August 22, 2013
Publication Date
January 1, 1994
Publication Information
Publication: International journal of plant sciences
Volume: 155
Issue: 2
ISSN: 1058-5893
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NCC2-101
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Life Support Systems
NASA Discipline Number 61-10
NASA Program CELSS

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