NO3 Medium Research Articles

Analysis of Nitrogen Utilization Capability during the Proliferation and Maturation Phases of Norway Spruce (Picea abies (L.) H.Karst.) Somatic Embryogenesis

Somatic embryogenesis (SE) is a laboratory-based method that allows for cost-effective production of large numbers of clonal copies of plants, of particular interest for conifers where other clonal propagation methods are mostly unavailable. In this study, the effect of l-glutamine as an organic nitrogen source was evaluated for three contrasted media (containing NH4 + NO3 without glutamine, or glutamine + NO3, or glutamine without inorganic nitrogen) during proliferation and maturation of Norway spruce somatic embryos through analyses of activities of the key enzymes of nitrogen metabolism: nitrate reductase (NR), glutamine synthetase (GS) and arginase. A major change in nitrogen metabolism was indicated by the increased activity of GS from zero in the proliferation stage through maturation to high activity in somatic embryo-derived plantlets; furthermore, NR activity increased from zero at the proliferation stage to high activity in maturing embryos and somatic-embryo derived plantlets. In contrast, arginase activity was high at all stages. In accordance with the GS and NR data, proliferation was fastest on the glutamine media, the largest number of mature embryos developed on the glutamine medium without inorganic nitrogen, and the ammonium content of proliferating cultures was much higher than that of mature somatic embryos. The best developed embryos, judged by germination, were from the glutamine + NO3 medium. These insights into nitrogen utilization will help to improve culture medium composition.

Thermodynamic studies of actinide complexes. 1. A reappraisal of the solution equilibria between plutonium(IV) and ethylenediaminetetraacetic acid (EDTAH4) in nitric media

Abstract A detailed reevaluation of the complexation equilibria of plutonium(IV) with the polyaminocarboxylic sequestering agent EDTA4− has been performed in 1 M (H,K)NO3 media at 298 K by means of visible absorption spectrophotometry and glass-electrode potentiometry at millimolar concentration levels. The high binding affinity even under strongly acidic conditions supports the exclusive formation of the neutral Pu(EDTA) complex over the range 0.01 ≤ [H+] ≤ 0.9 M with an apparent formation constant of log β110 = 25.8(1) at 0.9 M HNO3. Extrapolation to zero ionic strength using the SIT approach provides the first ever-reported NEA–TDB compliant estimate of β 110 0 ( log β 110 0 = 32.2 ( 3 ) ) . A global modeling procedure of the potentiometric data collected for three different metal over ligand ratios (1:1, 1:1.5, and 1:2) ascertained the formation of four additional species for pH values comprised between 2 and 6.5, namely [Pu(EDTA)(OH)]−, [Pu(EDTA)2H2]2−, [Pu(EDTA)2H]3−, and [Pu(EDTA)2]4−. The visible absorption spectra for the first three complexes have also been determined. Data recorded above pH 3.5 (for a 1:1 molar ratio) or 6.5 (for a 1:2 molar ratio) were finally excluded from the global fitting procedure as speciation calculations suggested the precipitation of amorphous Pu(OH)4(am) according to the latest critical value quoted in the literature for its solubility product.

Role of nitrite, a nitric oxide derivative, in K-Cl cotransport activation of low-potassium sheep red blood cells.

K-Cl cotransport (COT) is the coupled movement of K and Cl, present in most cells, associated with regulatory volume decrease, susceptible to oxidation and functionally overexpressed in sickle cell anemia. The aim of this study was to characterize the effect of the oxidant nitrite (NO2-) on K-Cl COT. NO2- is a stable metabolic end product of the short-lived highly reactive free radical nitric oxide (NO), an oxidant and modulator of ion channels, and a vasodilator. In some systems, the response to NO2- is identical to that of NO. We hypothesized that NO2- activates K-Cl COT. Low potassium (LK) sheep red blood cells (SRBCs) were used as a model. The effect of various concentrations (10(-6) to 10(-1) m) of NaNO2 was studied on K efflux in hypotonic Cl and NO3 media, Cl-dependent K efflux (K-Cl COT), glutathione (GSH), and methemoglobin (MetHb) formation. In support of our hypothesis, K efflux and K-Cl COT were stimulated by increasing concentrations of NaNO2. Stimulation of K efflux was dependent upon external Cl and exhibited a lag phase, consistent with activation of K-Cl COT through a regulatory mechanism. Exposure of LK SRBCs to NaNO2 decreased GSH, an effect characteristic of a thiol-oxidizing agent, and induced MetHb formation. K-Cl COT activity was positively correlated with Methb formation. N-ethyl-maleimide (NEM), a potent activator of K-Cl COT, was used to assess the mechanism of NO2- action. The results suggest that NEM and NO2- utilize at least one common pathway for K-Cl COT activation. Since NaNO2 is also a well known vasodilator, the present findings suggest a role of K-Cl COT in vasodilation.

Isolation and characterization of nitrate reductase deficient mutants of the ectomycorrhizal fungus Hebeloma cylindrosporum

To clarify the role of the fungal nitrate assimilation pathway in nitrate reduction by mycorrhizal plants, nitrate reductase (NR)-deficient (NR- ) mutants of the ectomycorrhizal basidiomycete Hebeloma cylindrosporum Romagnesi have been selected. These mutants were produced by u.v. mutagenesis on protoplasts originating from homokaryotic mycelia belonging to complementary mating types of this heterothallic tetrapolar species. Chlorate-resistant mutants were first selected in the presence of different nitrogen (N) sources in the culture medium. Among 1495 chlorate resistant mycelia, 30 failed to grow on nitrate and lacked a detectable NR activity. Growth tests on different N sources suggested that the NR activity of all the different mutants is specifically impaired as a result of mutations in either the gene coding for NR apoprotein or genes controlling the synthesis of the molybdenum cofactor. Furthermore, restoration of NR activity in some of the dikaryons obtained after crosses between the different mutant mycelia suggested that not all the selected mutations mapped in the same gene. Utilization of N on a NH4 15 NO3 medium was studied for two mutant strains and their corresponding wild-type homokaryons. None of the mutants could use nitrate whereas 15 N enrichment values indicated that 13-27% of N present in 13-d-old wild-type mycelia originated from nitrate. Apparently, the mutant mycelia do not compensate their inability to use nitrate by a more efficient use of ammonium. These different NR mutants still form mycorrhizas with the habitual host plant, Pinus pinaster (Ait.), making them suitable for study of the contribution of the fungal nitrate assimilation pathway to nitrate assimilation by mycorrhizal plants.

Oxidative activation of K-Cl cotransport by diamide in erythrocytes from humans with red cell disorders, and from several other mammalian species.

Red blood cells (RBCs) from different mammalian species were investigated for the presence of diamide-induced oxidative activation of K-Cl cotransport reported to be present in sheep but absent in human RBCs. K efflux was measured in RBCs from human with hemoglobin (Hb) A or S, glucose-phosphate dehydrogenase (G6PDH) and a cytoskeletal deficiency, and from rat, mouse and rabbit. RBCs were incubated with diamide (0-1.0 mm) in K-free Cl or NO3 media of variable osmolalities (200-450 mOsM). Cl-dependent K efflux or K-Cl cotransport (estimated as the difference between K efflux rate constants in Cl and NO3) was activated by diamide in a sigmoidal fashion. Relative maximum K-Cl cotransport followed the sequence: human HbA (1) < rabbit (1.8) < sheep (6.9) < human HbS (9.5) approximately rat (9.7). Relative diamide concentrations for half maximal activation of K-Cl cotransport followed the sequence: sheep (1.9) > human Hb A (1) > rabbit (0.75) > human HbS and rat (0.67). Cell swelling in 200 mOsM doubled K-Cl cotransport in diamide, both in human HbA and S cells but reduced that in rat RBCs. In contrast, cell shrinkage at 450 mOsM obliterated K-Cl cotransport in human HbA and S but not in rat RBCs. Human RBCs with G6PDH and a cytoskeleton deficiency behaved like HbA RBCs. In mouse RBCs, diamide-activated K-Cl cotransport was 30% higher in isotonic than in hypotonic medium. In human HbA and S, and in low or high K sheep RBCs fractionated by Percoll density gradient, diamide increased the activity of K-Cl cotransport, an effect inversely correlated with cell density. Analysis of pooled data reveals that K-Cl cotransport accounted for about 80% of all K flux in Cl. There was a statistically significant correlation between K-Cl cotransport and K efflux in Cl (P < 0. 00001) and in NO3 (P < 0.00001). In conclusion, a diamide-activated K-Cl cotransport was present in human RBCs and in all other mammalian RBCs tested, with a large inter-, and for human and sheep, intraspecies variability for its maximum activity.

Quinine and quinidine inhibit and reveal heterogeneity of K-Cl cotransport in low K sheep erythrocytes

Low K (LK) sheep red blood cells (SRBCs) serve as a model to study K-Cl cotransport which plays an important role in cellular dehydration in human erythrocytes homozygous for hemoglobin S. Cinchona bark derivatives, such as quinine (Q) and quinidine (QD), are effectively used in the treatment of malaria. In the present study, we investigated in LK SRBCs, the effect of various concentrations of Q and QD on Cl-dependent K efflux and Rb influx (K(Rb)-Cl flux), activated by either swelling in hyposmotic media, thiol alkylation with N-ethylmaleimide (NEM), or by cellular Mg (Mgi) removal through A23187 in the presence of external chelators. K efflux or Rb influx were determined in Cl and NO3 medium and K(Rb)-Cl flux was defined as the Cl-dependent (Cl minus NO3) component. K(Rb)-Cl flux stimulated by all three interventions was inhibited by both Q and QD in a dose-dependent manner. Maximum inhibition of K(Rb)-Cl flux occurred at Q and QD concentrations > or = 1 mM. The inhibitory effect of Q was manifested in Cl, but not in NO3, whereas QD reduced K and Rb fluxes both in Cl and NO3 media. The mean 50% inhibitory concentration (IC50) of Q and QD to inhibit K(Rb)-Cl flux varied between 0.23 and 2.24 mM. From determinations of the percentages of inhibition of the different components of K and Rb fluxes, we found that SRBCs possess a Cl-dependent QD-sensitive and a Cl-dependent QD-insensitive K efflux and Rb influx. These two components vary in magnitude depending on the manipulation and directional flux, but in average they are about 50% of the total Cl-dependent flux. This study raises the possibility that, in SRBCs, the Cl-dependent K(Rb) fluxes are heterogeneous.

Extraction equilibria of lead(II) from nitrate solutions with acidic organophosphorus compounds

AbstractThe distribution data were numerically analyzed for the extraction of trace lead(II) from 1·0 mol dm−3 (Li,H)NO3 media with toluene solutions of acidic organophosphorus compounds (HR), including di(2‐ethylhexyl)phosphoric acid (D2EHPA) and 2‐ethylhexylphosphonic acid mono‐2‐ethylhexyl ester (HEHEHP). The complex formulations were determined to be \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {{\rm PbR}_2 {\rm (HR)}},{\rm }\overline {{\rm PbR}_2 {\rm (HR)}_4 },{\rm and }\overline {{\rm Pb(NO}_3 {\rm )R}} $\end{document} for the D2EHPA system and to be \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {{\rm PbR}_2 {\rm (HR)}_{\rm 3} },{\rm }\overline {{\rm PbR}_2 {\rm (HR)}_4 },{\rm and }\overline {{\rm Pb(NO}_3 {\rm )R(HR)}} $\end{document} for the HEHEHP system. In this work, the equilibrium constants for the formation of these complexes were also given at 298 K.

K-Cl cotransport, pH, and role of Mg in volume-clamped low-K sheep erythrocytes: three equilibrium states.

Ouabain-resistant K efflux and Rb influx in Cl and NO3 media were studied in volume-clamped low-K (LK) sheep red blood cells (SRBC) with normal and experimentally reduced cytoplasmic Mg (Mgi) levels as function of pH and at 37 degrees C. Sucrose was added to solutions with constant ionic strength and variable pH to maintain normal cell volume. Cl-dependent ouabain-resistant K(Rb) fluxes (K-Cl cotransport) at unity relative cell volume exhibited a maximum at pH approximately 7 in normal-Mgi LK cells consistent with the apparent acid pH activation reported for human erythrocytes. However, in LK SRBC with Mgi lowered by A-23187 and an external Mg chelator, K(Rb)-Cl cotransport was reversibly activated as the pH was raised from 6.5 to 9. The alkaline pH effect on Cl-dependent Rb influx in low-Mgi LK SRBC was due to a 10-fold rise in the maximum velocity values without a major change in the Km values. The pH dependence of the experimental flux reversal point, i.e., the extracellular Rb concentration at which no net K-Cl cotransport occurs, approximately paralleled that of the flux reversal point predicted from the ratio of the ion products, in both control and low-Mgi LK cells, albeit with a small displacement to higher extracellular Rb concentration at all pH values. The kinetic data can be explained by a general minimum three-state equilibrium in which deprotonation recruits transporters from a resting R state into the active A state modified by Mgi to an inactive I state.(ABSTRACT TRUNCATED AT 250 WORDS)

Complex formation equilibria in iron(III)-L-alanine system

Complex formation in iron(III)-L-alanine solutions was studied by emf glass electrode and spectrophotometric measurements, in 0.5 mol dm −3 (Na)NO3 medium, at 25 ° C. In the concentration range 0.5 ⩽ [Fe]0 ⩽ 20.0, 5.0 ⩽ [Ala]0 ⩽ 1000.0 (mmol dm−3) and 1.0 ⩽ -log [H+] ⩽ 3.5; {[Ala]/[Fe] = 10:1-100:1| the equilibria in the title system were explained by the model including the species FeHL, FeL, Fe(OH)L, Fe2(OH)2L2 (where HL denotes L-alanine) and several hydrolytic products. The stability constants of complexes are given. The mechanism of formation and structure of complexes in solution is proposed.

Nitrogen metabolism inErica and soybean, two species differing by their sensitivity to inorganic N source

Growth of soybean was not altered, whatever the inorganic N-source (NO3, NH4 or a NO3/NH4 mixture); conversely, growth of Erica x darleyensis plants in vitro decreased more in. NH4 medium than in a NO3 medium, compared to a NO3/NH4 medium. The GS/GOGAT pathway (in NH4 medium), the nitrate and nitrite reductase activities (in NO3 medium), as the contents in free nitrogenous forms and total nitrogen (in NO3 and NH4 media) were not more altered in Erica than in soybean, compared to a NO3/NH4 medium. PEPCase activity was the highest in soybean irrespective of the N-treatments; the involvement of PEPCase in N-metabolism could be explained by its function in ionic and osmotic balances rather than its function in supplying carboxylates as acceptors for NH4-assimilation.

Hydrolysis of aluminum(III) ion in sodium nitrate medium

Hydrolysis of aluminum(III) ion in 3.0 M (Na)NO3 medium was studied by emf method at 25° C. Data cover the range 1–78 mM Al(III) within the pH range of 2.0–4.5. At a definite pH, the extent of hydrolysis increases with increasing aluminium concentration, thereby indicating the presence of polynuclear hydrolysis products. The least squares treatment of the data indicates the formation of polynuclear hydrolytic complexes [Formula: see text] [Formula: see text] and [Formula: see text] With the reactions written in the form[Formula: see text]the stability constants obtained were log (β2,2 = −7.55 ± 0.21, log β2,4 = −16.41 ± 0.13, and log (β3,4 = −13.24 ± 0.08. Distribution curves indicate that the complex [Formula: see text] is predominant. Key words: hydrolysis, aluminum(III) ion, hydrolytic complexes, aluminum(III) ion hydrolysis.

Study of Equilibria in the Aluminium(III)‐Glycine and ‐Alanine Systems

AbstractThe formation of various hydrolytic and mixed hydrolytic complexes of the aluminium(III) ion in the presence of glycine and L‐alanine, has been studied in 0.5 mol dm−3 (Na)NO3 medium at 25deg;C, by emf method. The concentration ratios of amine acids to aluminium(III) were varied from 1 : 1 to 10 : 1. The least‐squares treatment of the data obtained, in the absence of the amino acids, indicates the formation of the dimer, [Al2(OH)2]4+, and monomer, [AlOH]2+, with the stability constants log β22 = −7.03 ± 0.03 and log β11 = −5.65 ± 0.09, respectively. At pH values higher then ∼4.0 formation of the trimer [Al3(OH)4]5+ (log β34 = −12.60 ± 0.08) becomes significant. In the presence of amino acids the evidence has been found for the formation of [Al2(OH)4]2+ (log β24 = −15.65 ± 0.09). Besides the formation of the pure hydrolytic complexes, equilibria in the title systems can be explained by assuming the main reaction products to have the compositions [Al(OH)3Gly] (log β131 = −7.53 ± 0.04), [Al2(OH)2(Gly)2] (log β222 = 6.56 ± 0.09) and [Al(OH)3Ala] (log β131 = −7.70 ± 0.03), [Al2(OH)2Ala2] (log β222 = 7.23 ± 0.07).

Volume-sensitive, Cl-dependent K transport in resealed human erythrocyte ghosts

Potassium influx and efflux in Cl and NO3 media were measured in resealed ghosts prepared from human red cells. Cl-dependent K influx was three times that in intact cells and, as in intact cells, was partially supported by Br but not by thiocyanate (SCN). In other properties, this flux differed from that in intact cells: substitution of N-methylglucamine for Na did not decrease but rather increased Cl-dependent K influx, the affinity for external K was reduced, with a Km of 21.3 +/- 12.5 mM, and inhibition by furosemide and bumetanide was incomplete. Furosemide at 1 mM inhibited Cl-dependent influx by 26 and 51% at 4 and 20 mM K, respectively. Bumetanide inhibited Cl-dependent K influx by 0 and 55% at concentrations of 10 microM and 1 mM, respectively, in 4 mM K, with no further inhibition at 20 mM K. Neither the magnitude nor the properties of the flux were altered by preparing ghosts in the presence of 1,4-dithiothreitol, indicating that sulfhydryl oxidation was not responsible for the altered flux in ghosts. Treatment with N-ethylmaleimide (NEM) either before or after ghost preparation did not increase Cl-dependent K influx. However, Cl-dependent influx in ghosts could be augmented by increasing ghost volume or ATP content. Resealed human erythrocyte ghosts thus exhibit a volume- and ATP-sensitive, Cl-dependent K flux that differs substantially from the putative Na-K-Cl cotransport in intact cells in that it is independent of Na, is relatively resistant to furosemide and bumetanide, and has a low affinity for K.(ABSTRACT TRUNCATED AT 250 WORDS)

Haploid and diploid plant regeneration from protoplasts of anther callus in rice

The regeneration of haploid and diploid plants was demonstrated from protoplasts that were isolated from cell suspensions of anther callus in rice. The cell suspension in the AA medium that contained 4 amino acids as the sole nitrogen source was friable, finely dispersed, and readily released a large number of protoplasts. These protoplasts, subsequently cultured in NO3 medium that contained nitrate as the sole nitrogen source, formed compact calli. The compact calli produced green plants with a frequency of 24%. Out of 15 flowering plants, 4 were haploids, the others were diploids which showed a uniform morphology but varied in seed fertility from 95 to 0%.

Thermochemical and spectrophotometrical study of Ni(II) Complexes with Thiadiamines

AbstractNi(II) complexes of some linear tridentates with one sulphur and two nitrogen donors have been studied in aqueous solution at 25°C in 0.5 M (K)NO3 medium by means of the calorimetric and spectrophotometric technique. It is shown that the percentage facial isomer in the NiL2+ complexes becomes more important with increasing substitution on the nitrogen or sulphur donor atoms. The NiL22+ complexes most probably have a trans‐facial tetragonally distorted structure with four equatorially bound nitrogen donors and in axial position the sulphide donors. The same {Ni‐(N4S2)}2+ cation was also present in the NiL2(NO3)2 solid state compounds.

Determination of the composition and the stability constants of complexes of silver(I) with some sulphur containing pyridines a potentiometric investigation

AbstractA series of sulphide‐containing pyridines of general formulamagnified image(CH2)xSR where R = CH3, C2H5, CH2CH2OH and x = 1, 2 has been prepared and studied potentiometrically in the presence of Ag+ in 0.5 M (K)NO3 medium at 25°C.The complex formation is discussed in terms of the Taft σ*‐parameters for the substituents. In acid region, where the complexes AgLH2+ and AgL2H23+ were formed, coordination occurs through the thioether group. In neutral and alkaline medium their was evidence for the species AgL2H2+, AgL+, AgL2+, Ag2L22+ and Ag2L2+ in which Ag+S and Ag+magnified image bonds are involved. The five membered chelate rings for the AgL+ and AgL2+ species are found to be more stable than the six‐membered ones.

EQUILIBRIUM STUDIES OF COPPER(II) AND OF NICKEL(II) COMPLEXES WITH SULPHIDE CONTAINING α,ω-DIAMINES

Abstract The complex formation of Cu2+ and Ni2+ with 1,7-diaza-4-thiaheptane (2,2-NSN), 1,8-diaza-4-thiaoctane (2,3-NSN), 1,9-diaza-4-thianonane (2,4-NSN) and 1,9-diaza-5-thianonane (3,3-NSN) has been studied potentiometrically at 25°C in 0.5 mol dm−3 (K)NO3 medium. The formation constants of the CuL2+ complexes with the four ligands are 9.02, 10.03, 9.49 and 9.79 respectively. In these 1:1 complexes the ligands can be facially disposed. 2,2-NSN and 2,3-NSN also form a CuL2 2+ complex with log K2=5.24 and 2.86 respectively, whereas the hydrolysis constants of the [Cu(OH)L]+ species with the same ligands are 5.90 and 4.60. 2,3-NSN also forms the species CuHL3+ and CuHL2 3+, with protonation constants 4.77 and 9.7 respectively. With Ni2+ only 5,5- and 5,6-membered chelate ring systems are formed. With 2,2-NSN log K1=7.377 and log K2=6.142. With 2,3-NSN log > K1=5.989 and log K2=3.86. There is a six co-ordinate environment about the metal ion in the NiL2 2+ complexes. The Ni(II) complexes of the latter ligan...

Nitrogen absorption by plant root from the culture medium where organic and inorganic nitrogen coexist

Abstract Barleys were precuItured with organic nitrogen, inorganic nitrogen or with a combination of both, and the ability of the plant roots to absorb 15N-NO2 was investigated. A. Plant was water-cultured for 50 days in the medium containing NO3, NO3:Arg(2:1), NO3:Arg(1:1), NO3:Arg(l:2), Arg or His as nitrogen source. 1) All the plant water-cultured in the medium containing Arg and also His showed better growth than those grown in NO3 medium. 2) Pretreated plants with different nitrogen sources were introduced to 15N-N3, for 30 min. The newly absorbed nitrogen per dry matter of the root was the highest for the NO3 pretreatment, and its value was in proportional to the NO3 content in the pretreated medium. Pretreatment of His showed the same value as that of Arg. B. The plant, pretreated with NO3 or Arg as the sole source of nitrogen, was treated with 15N-NO3 or [ureido-15N]Arg for 30 min. 1) NO3-N was quickly metabolised into GluNH3> Glu>Ala and γ·AD in NO3 pretreatment, but, NO3-N was scarcely metabolised into them in Arg pretreatment. 2) On the other hand, Arg[ureido]-N was easily absorbed and incorporated into amides and amino acids in both nitrogen treatments. C. It can be concluded that nitrogen metabolism in the plant root is closely related to the difference in nitrogen pretreatment (organic, inorganic or both), hence, the amounts and varieties of absorbed nitrogens by the root would be affected at the treatment time.

Copper(II) Complexation by Fulvic Acid Extracted From Sewage Sludge as Influenced by Nitrate Versus Perchlorate Background Ionic Media

AbstractThe possible adverse effect of CuNO3+ ion pairs on studies of the complexes formed between Cu(II) and fulvic acid extracted from sewage sludge was investigated by potentiometric titration of 2 × 10−3M K/H fulvate with Cu(NO3)2 and Cu(C104)2, at pH 5 and 25°C, in ionic media of 0.1M KNO3 or KC104, respectively. It was shown that the degree of complexation of Cu2+ in the NO3 medium was always significantly greater than that in the C104 medium for total Cu concentrations in the range 10−4M to 10−2M. This result was interpreted as evidence for significant concentrations of CuNO3+ ion pairs and mixed CuNO3‐fulvate complexes in the NO3 medium. Further support for the existence of CuNO3+ in the NO3 medium was obtained through a successful calculation of the thermodynamic stability constant for this ion pair that employed data from blank titrations with Cu(NO3)2 and Cu(ClO4)2. It was concluded that ClO4 ionic media should be used instead of NO3 ionic media in studies of Cu(II) complexation with the functional groups of fulvic acid.

Maize growth as affected by root temperature and form of nitrogen

The maize inbred ND203 was grown in separate NH4 and NO3 nutrient solutions containing approximately 100 ppm N with root temperatures (RT) maintained at either 14.8 or 28.2°C. Nutrient solution composition had little effect on yield of roots or tops at 28.2°C (RT). Yields were greatly reduced in both nutrient solutions at 14.8°C (RT), but the yield reduction was greater in the NH4 nutrient medium apparently as a result of NH4 toxicity. The afflicted plants in the NH4 medium at 14.8°C (RT) contained the highest level of plant NH4-N, 0.12%, and had relatively wide NH4: K ratios. Tissue K concentration was reduced at the lower RT, and the reduction proportionately was greater in plants grown in the NH4 medium. NO3 concentration in the tops and to a lesser extent roots of ND203 grown in the NO3 medium was greatly reduced at 14.8°C (RT). Plants grown in the NH4 medium generally contained higher organic N concentrations. Influences of root temperature and form of nitrogen on the accumulation of Ca, Mg and Na are discussed.