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The influence of enriched rhizosphere CO2 on N uptake and metabolism in wild-type and NR-deficient barley plants.
- Source :
-
Physiologia Plantarum . May96, Vol. 97 Issue 1, p47-54. 8p. - Publication Year :
- 1996
-
Abstract
- Positive influences of high concentrations of dissolved inorganic carbon (DIC) in the growth medium of salinity‐stressed plants are associated with carbon assimilation through phosphoenolpyruvate carboxylase (PEPc) activity in roots; and also in salinity‐stressed tomato plants, enriched CO2 in the rhizosphere increases NO−3uptake. In the present study, wild‐type and nitrate reductase‐deficient plants of barley (Hordeum vulgare L. cv. Steptoe) were used to determine whether the influence of enriched CO2 on NO−3 uptake and metabolism is dependent on the activity of nitrate reductase (NR) in the plant. Plants grown in NH4+and aerated with ambient air, were transferred to either NO3− or NH4+ solutions and aerated with air containing between 0 and 6 500 μmol mol−1 CO2. Nitrogen uptake and tissue concentrations of NO3− and NH4+ were measured as well as activities of NR and PEPc. The uptake of NO−3 by the wild‐type was increased by increasing CO2. This was associated with increased in vitro NR activity, but increased uptake of NO3− was found also in the NR‐deficient genotype when exposed to high CO2 concentrations; so that the influence of CO2 on NO3− uptake was independent of the reduction of NO3− and assimilation into amino acids. The increase in uptake of NO3− in wild‐type plants with enriched CO2 was the same at pH 7 as at pH 5, indicating that the relative abundance of HCO3− or CO2 in the medium did not influence NO3− uptake. Uptake of NH4+ was decreased by enriched CO2 in a pH (5 or 7) independent fashion. Thus NO3− and NH+4 uptakes are influenced by the CO2 component of DIC independently of anaplerotic carbon provision for amino acid synthesis, and CO2 may directly affect the uptake of NO3− and NH4+ in ways unrelated to the NR activity in the tissue. [ABSTRACT FROM AUTHOR]
- Subjects :
- *CARBON
*SALINITY
*PLANTS
*METABOLISM
*PLANT roots
*NITRATES
Subjects
Details
- Language :
- English
- ISSN :
- 00319317
- Volume :
- 97
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- Physiologia Plantarum
- Publication Type :
- Academic Journal
- Accession number :
- 12658455
- Full Text :
- https://doi.org/10.1111/j.1399-3054.1996.tb00477.x