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Ammonium and nitrate uptake by soybean during recovery from nitrogen deprivation
- Source :
- Journal of Experimental Botany. 45:23-33
- Publication Year :
- 1994
- Publisher :
- Oxford University Press (OUP), 1994.
-
Abstract
- Soybean [Glycine max (L.) Merrill] plants that had been subjected to 15 d of nitrogen deprivation were resupplied for 10 d with 1.0 mol m-3 nitrogen provided as NO3-, NH4+, or NH4(+) + NO3- in flowing hydroponic culture. Plants in a fourth hydroponic system received 1.0 mol m-3 NO3- during both stress and resupply periods. Concentrations of soluble carbohydrates and organic acids in roots increased 210 and 370%, respectively, during stress. For the first day of resupply, however, specific uptake rates of nitrogen, determined by ion chromatography as depletion from solution, were lower for stressed than for non-stressed plants by 43% for NO3- resupply, by 32% for NH4(+) + NO3- resupply, and 86% for NH4+ resupply. When specific uptake of nitrogen for stressed plants recovered to rates for non-stressed plants at 6 to 8 d after nitrogen resupply, carbohydrates and organic acids in their roots had declined to concentrations lower than those of non-stressed plants. Recovery of nitrogen uptake capacity of roots thus does not appear to be regulated simply by the content of soluble carbon compounds within roots. Solution concentrations of NH4+ and NO3- were monitored at 62.5 min intervals during the first 3 d of resupply. Intermittent 'hourly' intervals of net influx and net efflux occurred. Rates of uptake during influx intervals were greater for the NH4(+)-resupplied than for the NO3(-)-resupplied plants. For NH4(+)-resupplied plants, however, the hourly intervals of efflux were more numerous than for NO3(-)-resupplied plants. It thus is possible that, instead of repressing NH4+ influx, increased accumulation of amino acids and NH4+ in NH4(+)-resupplied plants inhibited net uptake by stimulation of efflux on NH4+ absorbed in excess of availability of carbon skeletons for assimilation. Entry of NH4+ into root cytoplasm appeared to be less restricted than translocation of amino acids from the cytoplasm into the xylem.
- Subjects :
- inorganic chemicals
0106 biological sciences
Time Factors
Nitrogen
Physiology
chemistry.chemical_element
Plant Science
Plant Roots
01 natural sciences
03 medical and health sciences
chemistry.chemical_compound
Animal science
Nitrate
Botany
Ammonium
Amino Acids
Nitrogen cycle
030304 developmental biology
2. Zero hunger
chemistry.chemical_classification
0303 health sciences
Nitrates
food and beverages
Xylem
Metabolism
Hydrogen-Ion Concentration
Carbohydrate
6. Clean water
Amino acid
Quaternary Ammonium Compounds
chemistry
Soybeans
010606 plant biology & botany
Subjects
Details
- ISSN :
- 14602431 and 00220957
- Volume :
- 45
- Database :
- OpenAIRE
- Journal :
- Journal of Experimental Botany
- Accession number :
- edsair.doi.dedup.....3e88b54e9ac75ee8c131b3c679057254