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Title: Stored root carbohydrates can maintain root respiration for extended periods

Authors:
 [1];  [2]
  1. Savannah River Ecology Laboratory, University of Georgia, Aiken SC 29802 USA, Warnell School of Forestry and Natural Resources, University of Georgia, Athens GA 30602 USA
  2. Warnell School of Forestry and Natural Resources, University of Georgia, Athens GA 30602 USA
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1414991
Grant/Contract Number:
EM0004391
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
New Phytologist
Additional Journal Information:
Related Information: CHORUS Timestamp: 2017-12-27 14:30:41; Journal ID: ISSN 0028-646X
Publisher:
Wiley-Blackwell
Country of Publication:
United Kingdom
Language:
English

Citation Formats

Aubrey, Doug P., and Teskey, Robert O. Stored root carbohydrates can maintain root respiration for extended periods. United Kingdom: N. p., 2017. Web. doi:10.1111/nph.14972.
Aubrey, Doug P., & Teskey, Robert O. Stored root carbohydrates can maintain root respiration for extended periods. United Kingdom. doi:10.1111/nph.14972.
Aubrey, Doug P., and Teskey, Robert O. 2017. "Stored root carbohydrates can maintain root respiration for extended periods". United Kingdom. doi:10.1111/nph.14972.
@article{osti_1414991,
title = {Stored root carbohydrates can maintain root respiration for extended periods},
author = {Aubrey, Doug P. and Teskey, Robert O.},
abstractNote = {},
doi = {10.1111/nph.14972},
journal = {New Phytologist},
number = ,
volume = ,
place = {United Kingdom},
year = 2017,
month =
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on December 27, 2018
Publisher's Accepted Manuscript

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  • The relative use of new photosynthate compared to stored C for the production and maintenance of fine roots, and the rate of C turnover in heterogeneous fine-root populations, are poorly understood. We followed the relaxation of a 13C tracer in fine roots in a Liquidambar styraciflua plantation at the conclusion of a free-air CO2 enrichment experiment. Goals included quantifying the relative fractions of new photosynthate versus stored C used in root growth and root respiration, as well as the turnover rate of fine-root C fixed during [CO2] fumigation. New fine-root growth was largely from recent photosynthate, while nearly one-quarter ofmore » respired C was from a storage pool. Changes in the isotopic composition of the fine-root population over two full growing seasons indicated heterogeneous C pools; less than 10% of root C had a residence time < 3 months, while a majority of root C had a residence time > 2 years. Compared to a 1-pool model, a 2-pool model for C turnover in fine roots (with 5 and 0.37 yr-1 turnover times) doubles the fine-root contribution to forest NPP (9-13%) and supports the 50% root-to-soil transfer rate often used in models.« less
  • Soil respiration constitutes a major component of the global carbon cycle and is likely to be altered by climate change. However, there is an incomplete understanding of the extent to which various processes contribute to total soil respiration, especially the contributions of root and rhizosphere respiration. Here, using a stable carbon isotope tracer, the authors separate the relative contributions of root and soil heterotrophic respiration to total soil respiration in situ. The Free-Air Carbon dioxide Enrichment (FACE) facility in the Duke University Forest (NC) fumigates plots of an undisturbed loblolly pine (Pinus taeda L.) forest with CO{sub 2} that ismore » strongly depleted in {sup 13}C. This labeled CO{sub 2} is found in the soil pore space through live root and mycorrhizal respiration and soil heterotroph respiration of labile root exudates. By measuring the depletion of {sup 13}CO{sub 2} in the soil system, the authors found that the rhizosphere contribution to soil CO{sub 2} reflected the distribution of fine roots in the soil and that late in the growing season roots contributed 55% of total soil respiration at the surface. This estimate may represent an upper limit on the contribution of roots to soil respiration because high atmospheric CO{sub 2} often increases in root density and/or root activity in the soil.« less
  • The interaction of nitrate and carbohydrates on the nodulation of Phaseolus vulgaris has been examined using an isolated root culture system which allows feeding of nutrients via the base of the root or external feeding via the medium in which it grows. The evidence presented is not compatible with the hypothesis that a carbohydrate-nitrogen balance in the host regulates rhizobial nodule formation. It supports, instead the concept that there are 2 apparently separate effects of nitrate which depend on the place of application to the root. Externally supplied nitrate inhibited the nodulation of roots fed 2% sucrose via their bases.more » The inhibition of 4.4 x 10/sup 5/ M nitrate could be prevented by raising the level of sucrose fed via the bases to 5 or 10% or by externally adding 0.2% sucrose, mannitol or L-arabinos. L-arabinose, which was inhibitory to nodulation and root growth by itself, was also tested at external concentrations as low as 0.005%, but no prevention of inhibition by 4.4 x 10/sup 3/ M nitrate was obtained below 0.05% arabinose. Nitrate supplied via the base of the root had no effect on nodulation with roots fed 2% sucrose and promoted the nodulation of roots fed 5 or 10% sucrose. The inhibition of nodulation of 2% sucrose roots by nitrate added externally was unaffected when nitr« less
  • Respiration in 1 cm oat root segments bathed in 1/4 strength Hoagland's solution was determined to be 230 ..mu..l O/sub 2//g fr wt/hr. When 1mM CdSO/sub 4/ was added the respiratory activity was retained at the control levels up to 2 hrs followed by an inhibition to 30 to 50% of control rates after 5 days. Influx and efflux of potassium (K) was monitored employing Rb/sup 86/ as a K marker. Short term (5-10 min) uptake kinetics of K are not altered in the presence or absence of Cd. After 60 min of Cd treatment the K uptake was 71%more » of control rates of 2 ..mu.. moles/g fr wt/hr. With a 2 hr Cd pretreatment K uptake was lowered to 10% of control rates. Cd pretreatment K uptake was lowered to 10% of control rates. Cd does not alter significantly either plasmalemma or tonoplast permeabilities as determined by Rb/sup 86/ efflux. A membrane bound, K stimulated, magnesium dependent, acid ATPase was assayed in the presence and absence of Cd. The stimulation due to K was 4.1 ..mu.. moles P released/mg protein/hr but in the presence of Cd and K stimulation was 12% of controls. Root segment ATP levels in control and 2 hrs of Cd treatment were determined by luciferin-luciferase assays. The control roots contained 10 n moles ATP/g fr wt/hr and the Cd treated roots contained 76% of these control values.« less