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Cyclic variations in nitrogen uptake rate of soybean plants: effects of external nitrate concentrationNet uptake of NO3- by non-nodulated soybean plants [Glycine max (L.) Merr. cv. Ransom] growing in flowing hydroponic cultures containing 0.5, 1.0 and 10.0 mol m-3 NO3- was measured daily during a 24-d period of vegetative development to determine if amplitude of maximum and minimum rates of net NO3- uptake are responsive to external concentrations of NO3-. Removal of NO3- from the replenished solutions during each 24-h period was determined by ion chromatography. Neither dry matter accumulation nor the periodicity of oscillations in net uptake rate was altered by the external NO3- concentrations. The maxima of the oscillations in net uptake rate, however, increased nearly 3-fold in response to external NO3- concentrations. The maxima and minima, respectively, changed from 4.0 and 0.6 mmol NO3- per gram root dry weight per day at an external solution level of 0.5 mol m-3 NO3- to 15.2 and -2.7 mmol NO3- per gram root dry weight per day at an external solution level of 10.0 mol m-3 NO3-. The negative values for minimum net uptake rate from 10.0 mol m-3 NO3- solutions show that net efflux was occurring and indicate that the magnitude of the efflux component of net uptake was responsive to external concentration of NO3-.
Document ID
Document Type
Reprint (Version printed in journal)
Tolley-Henry, L. (North Carolina State University Raleigh 27695-8002, United States)
Raper, C. D. Jr
Granato, T. C.
Raper CD, J. r.
Date Acquired
August 22, 2013
Publication Date
May 1, 1988
Publication Information
Publication: Journal of experimental botany
Volume: 39
Issue: 202
ISSN: 0022-0957
Subject Category
Life Sciences (General)
Funding Number(s)
Distribution Limits
Non-NASA Center
NASA Discipline Life Support Systems
NASA Discipline Number 61-10