Ectomycorrhizas Affect Ionic Balance During Ammonium Uptake by Douglas‐fir Roots

Bledsoe, Caroline S.; Rygiewicz, Paul T.

doi:10.1111/j.1469-8137.1986.tb00581.x

Cited by 37 publications

(22 citation statements)

References 26 publications

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“…For nitrate they even found a maximum ratio of 16 mmol O H -per mmol nitrate taken up (Rygiewicz et al 1984b). These results are difficult to explain on the basis of the current ionic balance theory and the authors suggest that ionic balance regulation in conifers might differ from that in agricultural plants (see also Bledsoe and Rygiewicz, 1986). The values calculated in the experiment presented here do not support the hypothesis of a conifer-specific ionic balance, as suggested by Rygiewicz and colleagues.…”

Section: H ÷ / O H -Excretioncontrasting

confidence: 54%

Nitrogen nutrition of Douglas-fir (Pseudotsuga menziesii) on strongly acid sandy soil

Gijsman¹

1990

Plant Soil

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Three-year old Douglas-fir trees were grown on a strongly acid sandy soil (pH-H20 3.87), fertilized with three different sources of nitrogen (nitrate, ammonium, or both) at three levels of N-supply (10, 50, 100 mg kg-1). Rhizosphere pH was determined and calculations were done on the relative contribution of both ammonium and nitrate uptake to total N uptake, and on the H + excretion by the roots.With ammonium nutrition the rhizosphere pH was slightly lower than the bulk soil pH, without any relationship with N level. With nitrate or ammonium nitrate nutrition, the rhizosphere pH was slightly lower than the bulk soil pH at low levels of N supply, but at higher N-levels a shift to a more alkaline rhizosphere occurred with these N-sources.Except with very low nitrate availability, the contribution of nitrate to total N uptake was higher than the nitrate fraction in N input. This may be caused by differences in preferred N source and in mobility of ammonium and nitrate in the soil. The calculated H + excretion was in agreement with the pattern in rhizosphere pH measured. Values were similar to those commonly found for other species.

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Section: H ÷ / O H -Excretioncontrasting

confidence: 54%

Nitrogen nutrition of Douglas-fir (Pseudotsuga menziesii) on strongly acid sandy soil

Gijsman¹

1990

Plant Soil

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“…a net OH" efflux occurred (Bigg & Daniel, 1978, using Pinus contorta Loud., Pimu engelniaitii Carr. and (as did Bledsoe & Rygiewicz, 1986) Pseudotosuga menziesii). Bledsoe & Zasoski (1983), using soil-grown Pseudotsuga menziesii, also found an OH" efflux with NO3" as N source.…”

Section: {D) No Dry Deposition An Equation Describing the Assimilamentioning

confidence: 78%

Acquisition of nitrogen by the shoots of land plants: its occurrence and implications for acid‐base regulation

Raven

1988

New Phytologist

128

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summary The typical N source for terrestial vascular plants is the soil in which they are rooted. N exchange between the aerial shoot and its environment, as gaseous, dissolved or particulate N, can involve either net loss or net gain of N by the plant. Net gain of N by the plant shoot at the expense of its aerial environment can be significant, under natural or agricultural conditions, for all three forms of aerial N (NH3,N2,NO3), Gaseous N gain can be substantial, as NH3, for plants growing on soils receiving large inputs of animal excreta and faeces. Soluble N uptake by shoots is the major N source for ‘atmospheric’ epiphytes. Particulate N supply to shoots is a major N source for carnivorous plants. Experimentally, several plants which normally grow with N supply mainly via their roots can be grown with a predominant, or sole, supply via their shoots. Plant growth with CO2, as C source, SO42− as S source and H2PO4, as P source generates excess OH (∼ 0.78 OH−/N assimilated) in the synthesis of core metabolites when the N source is NO3− supplied to roots or shoots. All other N sources (except dicarboxylic amino‐acids) yield excess H+during synthesis of core metabolites. NH4+ (in solution) supplied to roots or shoots yields some 1.22 H+/N assimilated, while NH3, N2 or NO2 supplied to shoots as gases, dissolved urea supplied to shoots or roots, and animal protein supplied to shoots of carnivorous plants, yields some 0.22 H+/N assimilated. These biochemically caused acid‐base perturbations may be exacerbated (NO2) or partially or, occasionally, completely offset (NH3) by effects related to solution and dissociation of the gas in growing shoots. Assimilation of the shoot‐acquired N in the shoots leads to somewhat different constraints on acid‐base homoiostasis relative to those found with assimilation of root‐acquired N. The shoot cannot generally excrete excess H+ or OH− to its environment (as is so for root‐assimilation of N), nor can it dispose of H+ biochemically without co‐operation of root metabolism and root–shoot and root‐rhizosphere transport processes. Excess OH− from shoot‐acquired and shoot‐assimilated NO3− can, by contrast, be disposed of biochemically after the fashion of root‐acquired, shoot‐assimilated NO3−. Tentative conclusions as to the disposal of excess H+ generated in shoot acquisition and assimilation of N‐sources other than NO3− and NO2− are different for rhizophytes and for haptophytes. Rhizophytes probably carry out a net synthesis of organic acid in the roots, with subsequent cation‐H+ exchange at the root plasmalemma, transport of cation salt of the organic acid to the shoot in the xylem, and metabolism of the organic acid anion in the shoot to yield OH−. Haptophytes probably have an excess of liquid water supply over their needs for growth and transpiration due to the very low N concentration in this water; they thus have the potential for H+ (as strong acid) excretion to the excess surface water which is lost, at least in part, as liquid water.

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“…Therefore the term carboxylates is preferred to organic anions (Van Tuil, 1965). Rygiewicz et al (1984a;b) and Bledsoe and Rygiewicz (1986) determined nutrient uptake and H+/OH--excretion of Douglas-fir and several other coniferous species. They found that the amount of H+/OH--ions excreted per unit nitrogen taken up was very much higher than commonly reported for other plant species; they also found a very high production of carboxylates.…”

Section: Introductionmentioning

confidence: 99%

Nitrogen nutrition of Douglas-fir (Pseudotsuga menziesii) on strongly acid sandy soil

Gijsman¹

1990

Plant Soil

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Through ionic balance calculations, the effect of different sources and levels of nitrogen on nutrient uptake by Douglas-fir was studied. With ammonium as the sole source of N, growth of the plants was very poor. Increasing the levels of ammonium supply strongly decreased the surplus of total inorganic cations (C) over total inorganic anions (A). This decrease in C-A value, corresponding to the level of carboxylates in the plant, implies that in the long term the plant will run out of carboxylates and will then no longer be able to eliminate protons in the cytoplasm, produced during assimilation of ammonium. This can lead to internal acidification of the plant, toxic concentrations of free ammonium and an unbalanced amino acid composition. Values for the ratio of net carboxylate production and organic nitrogen production were in the same range as commonly found for other species. This did not support the theory of a conifer-specific ionic balance regulation as posed by others.

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Ectomycorrhizas Affect Ionic Balance During Ammonium Uptake by Douglas‐fir Roots

Cited by 37 publications

References 26 publications

Nitrogen nutrition of Douglas-fir (Pseudotsuga menziesii) on strongly acid sandy soil

Nitrogen nutrition of Douglas-fir (Pseudotsuga menziesii) on strongly acid sandy soil

Acquisition of nitrogen by the shoots of land plants: its occurrence and implications for acid‐base regulation

Nitrogen nutrition of Douglas-fir (Pseudotsuga menziesii) on strongly acid sandy soil

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