Effect Of NH Research Articles

Effects of NH4 +-N: NO3 --N ratio on growth, nutrient uptake and production of blueberry (Vaccinium spp.) under soilless culture.

Blueberry (Vaccinium corymbosum) is a small pulp shrub, which prefers to grow on a soilless culture. For soilless culture, nutritional management remains typically vital for blueberry production. However, the effect of different nutritional treatments on blueberry growth and production is largely unknown. This study was designed to investigate to formulate a specific nutritional treatment for blueberry. The results showed that NH4 +-N: NO3 --N ratios significantly affected the growth, nutrient uptake, physiological characteristics, and flowering, as well as the fruiting characteristics of blueberry plants. The number of shoots and top projection area was increased considerably by 25:75 treatment. In contrast, 50:50 treatment promotes plant height, shoot length, and stem thickness, increasing chlorophyll contents, photosynthetic capacity, and P, Ca, and Mg in leaves. In contrast, 50:50 treatment promotes the flowering fruiting rate and prolongs the blueberry flowering period. The maximum soluble sugar contents were noted in 25:75, while maximum starch contents were reported in the 50:50 treatment. The treatments 100:0 and 75:25 promote early flowering and accelerate fruit set. Notably, NH4 +-N: NO3 --N ratios; 50:50 treatment significantly encourages plant growth, nutrient uptake, chlorophyll contents, photosynthetic capacity, and fruit setting rate in blueberry plants. These findings suggested that NH4 +-N: NO3 --N ratios 50:50 is the most appropriate treatment that significantly promotes vegetative growth and enhances production in blueberry plants. This study provides valuable information for improved blueberry production under a controlled environment.

Key role of NH4+-N in the removal of oxacillin during managed aquifer recharge: Reconsidering the recharge limitation

Frequent occurrence of trace antibiotics in reclaimed water is concerning, which inevitably causes aquifer contamination in the case of managed aquifer recharge (MAR). Global governments have formulated strict reclaimed water standards to ensure the safety of water reuse. Recent studies have found that improved antibiotics removal is intimately associated with high ammonia-oxidizing activity. However, the role of NH4+-N in the removal of residual antibiotics of reclaimed water during MAR remains unknown. NH4+-N removal and the effects of ammonia oxidation on antibiotics biodegradation in the aquifer are the most significant facts for solving the above collision. In this work, the effects of NH4+-N (0, 1 and 5 mg/L) in a model refractory antibiotic (oxacillin (OXA), 100 μg/L) attenuation were deciphered by employing three individual simulated MAR columns, which so called N0, N1 and N5. The results showed that 5 mg/L NH4+-N in influent upregulated the abundance of amo genes by 28.9 %-68.0 % in N5. And the enriched functional genes encoding key degradation enzymes enhanced the OXA removal by 18.7 % and alleviated the oxidative stress caused by antibiotics. Subsequently, antibiotic resistance genes (ARGs), mobile gene elements (MGEs) and human bacterial pathogens (HBPs) abundance were all significantly decreased. Moreover, the intimate association between ammonia-oxidizing microorganisms (AOM) and candidate OXA degraders based on microbial network analysis further supported the significance of AOM on OXA biodegradation. This study provides comprehensive evidence that appropriate amounts of NH4+-N are beneficial in antibiotics and antibiotic resistance risk reduction, providing compelling insights for refine NH4+-N recharge limitation.

Microbial mechanisms in nitrogen fertilization: Modulating the re-mobilization of clay mineral-bound cadmium in agricultural soils

Soil cadmium (Cd) can affect crop growth and food safety, and through the enrichment in the food chain, it ultimately poses a risk to human health. Reducing the re-mobilization of Cd caused by the release of protons and acids by crops and microorganisms after stabilization is one of the significant technical challenges in agricultural activities. This study aimed to investigate the re-mobilization of stabilized Cd within the clay mineral-bound fraction of soil and its subsequent accumulation in crops utilizing nitrogen ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3−-N), at 60 and 120 mg kg−1. Furthermore, the study harvested root exudates at various growth stages to assess their direct influence on the re-mobilization of stabilized Cd and to evaluate the indirect effects mediated by soil microorganisms. The results revealed that, in contrast to the NO3−-N treatment, the NH4+-N treatment significantly enhanced the conversion of clay mineral-bound Cd in the soil to NH4NO3-extractable Cd. It also amplified the accumulation of Cd in edible amaranth, with concentrations in roots and shoots rising from 1.7–6.0 mg kg−1 to 4.3–9.8 mg kg−1. The introduction of NH4+-N caused a decrease in the pH value of the rhizosphere soil and stimulated the production and secretion organic and amino acids, such as oxalic acid, lactic acid, stearic acid, succinic acid, and l-serine, from the crop roots. Furthermore, compared to NO3−-N, the combined interaction of root exudates with NH4+-N has a more pronounced impact on the abundance of microbial genes associated with glycolysis pathway and tricarboxylic acid cycle, such as pkfA, pfkB, sucB, sucC, and sucD. The effects of NH4+-N on crops and microorganisms ultimately result in a significant increase in the re-mobilization of stabilized Cd. However, the simulated experiments showed that microorganisms only contribute to 3.8–6.6 % of the re-mobilization of clay mineral-bound Cd in soil. Therefore, the fundamental strategy to inhibit the re-mobilization of stabilized Cd in vegetable cultivation involves the regulation of proton and organic acid secretion by crops.

Effect of NH4+ and NO3− cooperatively regulated carbon to nitrogen ratio on organic nitrogen fractions during rice straw composting

The purpose of this study was to examine the effects of replacing urea with inorganic nitrogen on the organic nitrogen sequestration process and the mitigation of nitrogen loss during rice straw composting. These groups include a control group with urea addition (CK), a group with (NH4)2SO4 addition (NH), a group with KNO3 addition (NO), and a group with (NH4)2SO4 + KNO3 addition (NN). The results demonstrated that adding NH, NO, and NN significantly increased the content of bioavailable organic nitrogen in the composting. Furthermore, compared to the CK, the NH treatment reduced nitrogen loss by 8.41 %. Structural equation modeling revealed the correlation between bacterial communities and organic nitrogen fractions in different treatment groups. Comparisons of nitrogen efficacy and nitrogen loss indicated that adding (NH4)2SO4 was more effective during composting, which provided a meaningful research basis for rice straw composting.

Rhizocompartmental microbiomes of arrow bamboo (Fargesia nitida) and their relation to soil properties in Subalpine Coniferous Forests.

Arrow bamboo (Fargesia nitida) is a pioneer plant in secondary forest succession in the Sichuan Province mountains. To comprehensively investigate the microbial communities and their functional variations in different rhizocompartments (root endosphere, rhizosphere, and root zone) of arrow bamboo (Fargesia nitida), a high-throughput metagenomic study was conducted in the present study. The results showed that the abundances of the dominant bacterial phyla Proteobacteria and Actinobacteria in the bamboo root endosphere were significantly lower than those in the rhizosphere and root zones. In contrast, the dominant fungal phyla, Ascomycota and Basidiomycota, showed the opposite tendency. Lower microbial diversity, different taxonomic composition and functional profiles, and a greater abundance of genes involved in nitrogen fixation (nifB), cellulose degradation (beta-glucosidase), and cellobiose transport (cellulose 1, 4-beta-cellobiosidase) were found in the bamboo root endosphere than in the other rhizocompartments. Greater soil total carbon, total nitrogen, NH4+-N, microbial biomass carbon, and greater activities of invertase and urease were found in the bamboo root zone than in the adjacent soil (spruce root zone). In contrast, the soil microbial community and functional profiles were similar. At the phylum level, invertase was significantly related to 31 microbial taxa, and the effect of NH4+-N on the microbial community composition was greater than that of NO3--N. The soil physicochemical properties and enzyme activities were significantly correlated with microbial function. These results indicate that the root endosphere microbiomes of arrow bamboo were strongly selected by the host plant, which caused changes in the soil nutrient properties in the subalpine coniferous forest.

Effects of NH+4 concentration on the vaterite formation via direct carbonation use waste carbide slag under the different ammonium systems

The effect of NH+4 concentration on the formation process of vaterite under three special systems containing NH+4 was investigated via direct carbonation of waste carbide slag. The synergistic effects of NH+4 with organic (CH3COO-) and inorganic (S2O2–8) systems on vaterite formation were systematically studied. The obtained particles were characterized by X-ray powder diffraction (XRD), scanning electron spectroscopy (SEM), dynamic light scattering (DLS) and thermogravimetric analysis (TGA) analytical techniques. The results show that the content of vaterite significantly increases when the presence of NH+4, and the maximum content of vaterite is 93.37%, 95.78% and 95.39% in NH4Cl, CH3COONH4 and (NH4)2S2O8 systems. The different systems affect the vaterite particle content, morphology, particle size and distribution at the same NH+4 concentration was studied. Mechanistic analysis shows that NH+4 can change the leaching rate of Ca2+, CH3COO- can adsorb on the vaterite surface, and S2O2–8 can make the CaSO4 intermediate appear in the reaction system. Apparent synergistic interactions between NH+4 and CH3COO-, S2O2–8 affect the nucleation and growth process of vaterite. This study can provide theoretical support for the preparation of vaterite, the functional utilization of waste carbide slag, and the mineralization of CO2.

Effect of NH4+ and SO42− ions on the solubility and solvation thermodynamics of l-proline at different temperatures

The solubility in most of the amino acids in electrolyte-containing water has a significant role on their solvation thermodynamics, which in turn affects their biophysical actions within the human body. Our current research is focused on the solubility and thermodynamic behaviour of an important amino acid l-Proline, given its diverse range of applications. For l-Proline, the solubility is influenced in distinct ways by various electrolytes. In this work we have reported for the first time the influence of ammonium sulphate [(NH4)2SO4] on the solubility and related transfer thermodynamics for better understanding of solvation characteristics of l-Proline in electrolytic solvent systems. It is found that the presence of polyvalent anion and dissociation character of (NH4)2SO4 control the solubility of l-Proline in both aqueous and electrolytic media which is justified by various thermodynamic parameters.

Effect of NH2-MWCNTs sprayed carbon fiber on the mechanical properties of carbon fiber reinforced polycarbonate composite for lightweight structural applications

In this work, amine-Multi-walled Carbon Nanotubes (MWCNTs) were reinforced on the surface of fiber fabric by solvent spray deposition method in order to improve the mechanical and thermal properties of carbon fiber/polycarbonate film (CF/PC) stacked composites. The hot press method was used to fabricate the CF/PC composites with varied NH2-MWCNTs concentrations of 0.1, 0.3, 0.5, and 0.7 wt.%, as well as the reference composite. The multifarious assembly features of Carbon nanotubes (CNTs) on the fiber surface exhibit greater interfacial mechanics and have a major influence on the load transfer efficiency of the composite. In comparison with reference CF/PC composite, the tensile strength (384.55 MPa) and modulus (23.78 GPa) of composites increase by 67% and 40% respectively for 0.1% NH2-MWCNT reinforcement, whereas flexural strength and flexural modulus increase by 98% and 80%. However, as compared to the 0.1% CNT reinforcement, the impact strength of the 0.7% increases over 6% by absorbing substantial fracture energy. The inclusion of MWCNTs lowers the glass transition temperature (Tg) of composites due to the role of molecular conformations in free surface volume of the polymer. X-ray Photoelectron spectroscopy (XPS) and FTIR analysis confirms the functional groups present in the nanocomposite. Field Emission Scanning electron microscopy (FESEM) was used to analyze the dispersion and adhesion surface morphology of MWCNTs on fiber and the fiber/matrix interface interaction fractograph of tensile and impact tested samples.

Effects of NH4+ doping on the hydrogen storage properties of metal hydrides

Doping can modify the properties of metal hydrogen storage materials significantly. Currently, the metal doping is a frequent strategy, while the non-metal cation doping has not been examined extensively so far. In this study, the effects of NH4+ doping on the hydrogen storage properties of different metal hydrides, including TiH2, Ti0·25V0·25Nb0·25Zr0·25H2, Ti0·5V0·5H2 and VH2, are investigated by first-principles calculations. It is found that the NH4+ presents a good affinity for metal hydrides and the NH4+ incorporation leads to charge redistribution and formation of dihydrogen bond. Furthermore, the NH4+ doping in metal hydrides is favorable for enhancing the hydrogen storage capacity and decreasing the thermal stability simultaneously. The possible reason for the NH4+ doping induced destabilization in metal hydrides is the relatively weak interaction between NH4+ and hydrogen atoms.

Effect of Intermediate Radicals on NOx and De‐NOx Characteristics of NH3/H2/Air Flames at High Pressure

AbstractThe effect of NH, NH2, and HNO on NOx and De‐NOx chemistry of a NH3/H2/air mixture at a pressure of 20 bar is investigated. Results suggest that the increase in pressure reduces NOx emissions and increases HO2 radical production through the reaction H + O2(+M) → HO2(+M). In contrast with OH and O radicals, the HO2 radical is less reactive, which prevents NO formation. The fuel‐bound NOx emissions mainly depend on the reactions NH + OH → NO + H, HNO(+M) → NO + H(+M), HNO + OH → NO + H2O, and HNO + O2 → NO + HO2, and thermal NOx depends on the reactions N + O2 → NO + N and N + OH → NO + H. At a pressure of 20 bar, the N2O is further converted to NO2 and N2 through the reaction N2O + NO → NO2 + N2. The abundance of HO2 radicals at high pressure also initiates the conversion of NO to NO2 via the reaction NO + HO2 → NO2 + H.

Acceleration of pitting corrosion of 70Cu–30Ni alloy in seawater by NH4+ and stress

The 70Cu–30Ni alloy has excellent resistance to seawater corrosion, but corrosion perforation still occurs during use for various reasons. Copper can suffer severe ammonia corrosion in NH4+ containing solutions and copper alloys are susceptible to stress corrosion in ammonia environments. Therefore, the effect of NH4+ and stress on the corrosion of 70Cu–30Ni alloy in seawater cannot be ignored. The main objective of this study was to investigate the accelerating effect of NH4+ and stress on the pitting of 70Cu–30Ni alloy. The effect of NH4+ and stress on the pitting of 70Cu–30Ni alloy in seawater was investigated using laser confocal scanning microscopy (LCSM), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results show that in seawater with NH4+ the depth and diameter of the pits and the number of pits in the specimens increase. NH4+ destroys the oxide film on the surface of the 70Cu–30Ni alloy and inhibits the repair process of the oxide film on the surface of the alloy, thus reducing the amount of protective Cu2O and NiO in the corrosion products of the specimen. In seawater with NH4+, the film capacitance CPEf and dispersion coefficient of the 70Cu–30Ni alloy interface are significantly lower, the oxide film is thinner and there are more local defects and poor protection. After loading stress, the pitting depth of the specimen increases further, showing stress corrosion cracking. Stress and NH4+ have a synergistic effect on the pitting corrosion of the alloy.

Effects of NH4 +/citrate complexing agent ratio on Ni-Mo and Ni-Mo-O electrodeposits from ammonium citrate baths.

To understand the effect of complexing agents (i.e., ammonium and citrate) in nickel–molybdenum electrodeposition, calculation of the concentration of various Ni and Mo species as a function of pH and initial concentration of metal ions and complexing agents was performed. In addition, linear sweep voltammetry and Hull cell experiments were systematically investigated to understand the effect of current density and ammonium-to-citrate ratio to film compositions, morphology, and crystallinity. The results indicated that Ni(NH3)3 2+ played a critical role in induced co-deposition mechanism of Ni–Mo alloys, which involved the reduced Ni and absorbed H atoms. Microstructure analysis of deposits indicated that the transition from smooth laminarly grown amorphous Ni–Mo–O composites to columnar and nanocrystalline metallic Ni–Mo alloys with a globular structure as the ammonium-to-citrate molar ratio increases. The highest Mo content of alloys was as high as 19 at%, and up to 70 at% O was present in the composites.

Ammonia mitigation and induction effects on hydrogen environment embrittlement of SCM440 low-alloy steel

The effect of ammonia (NH 3 ) contained in hydrogen (H 2 ) gas on hydrogen environment embrittlement (HEE) of SCM440 low-alloy steel was studied in association with the NH 3 concentration, loading rate, and gas pressure. NH 3 worked as both mitigator of the HEE and inducer of hydrogen embrittlement (HE) depending on the testing conditions. The mitigation of the HEE was achieved by the deactivation of the iron (Fe) surface for H 2 dissociation caused by the preferential adsorption of NH 3 on the Fe surface, which is enhanced by the increase in the NH 3 concentration and decrease in the H 2 gas pressure. NH 3 induced HE was caused due to creating hydrogen by the NH 3 decomposition. Since the NH 3 decomposition rate is low, the induction effect was observed when the loading rate was low. The effect of NH 3 was determined by the competition of the mitigation and induction effects. • NH 3 worked as both mitigator and inducer of hydrogen embrittlement. • The effects of NH 3 depended on NH 3 concentration, loading rate, and gas pressure. • NH 3 mitigated hydrogen environment embrittlement by hindering hydrogen uptake into the material. • NH 3 induced hydrogen embrittlement by creating hydrogen by its decomposition.

Decreased Solution pH and Increased K+ Uptake Are Related to Ammonium Tolerance in Hydroponically Cultured Plants

The ammonium (NH4+) tolerance of plants is an important issue in agriculture, associated with several plant characteristics. So far, plant tissue acidification has been shown as the primary cause of NH4+ toxicity. Suppressed plant growth caused by excess NH4+ can be counteracted by potassium (K+) application. However, the effects of NH4+ tolerances on the differences regarding pH changes together with K+ uptake remain to be determined. Here, we performed an 84 h hydroponic cultivation of five species with different NH4+ tolerances, subjected to three NH4+:NO3− solutions (0:100, 50:50, or 100:0), to investigate the pH changes and ion uptakes. Consequently, the solution pH was lowered over time to varying extents in the presence of NH4+. The NH4+-tolerant ageratum and lettuce, shown to be tolerant to NH4+ in this trial, rapidly lowered the solution pH, whereas extremely NH4+-sensitive salvia and cabbage only gave a minor decrease in the solution pH when grown with 100:0 NH4+:NO3−. Additionally, the increased external NH4+ level led to a substantial decline in the net cation influxes (K+, Ca2+, and Mg2+). As compared to solely NH4+-fed salvia and cabbage, solely NH4+-fed ageratum and lettuce ultimately showed a relatively greater net K+ influx. Taken together, this study discusses how the decreases in pH and K+ are related to NH4+ tolerance in five hydroponically cultured species.

Ammonium and nitrate impact petal color traits and amino acid profiles differently in <i>Petunia</i>

Nitrogen (N) is vital for ornamental plants to fulfill fundamental cellular functions. Effects of inorganic N including nitrate and ammonium on ornamental traits at the biochemical level are less reported. Given that the continuously increased concentration of CO₂ in atmosphere has greater negative effects on nitrate reduction than ammonium utilization in C₃ plants, it is vital for us to dissect various effects of different inorganic N forms on flower development, which will lead to a better understanding of the metabolic regulation of ornamental traits. In this study, <italic>Petunia x hybrida</italic> cv 'Mitchell Diploid' (MD) plants at 6~8-leaf stage were treated hydroponically with the same and regular amount of inorganic N for one month but in three different forms, 1mM NH₄NO₃ as the control (NH₄NO₃), 2mM NH₄Cl alone (NH₄-N) and 2mM NaNO₃ alone (NO₃-N). Results indicated that relative to the control, effects of NH₄-N and NO₃-N treatment alone on plant growth, N utilization and distribution, petal color traits and petal amino acid profiles were different by varying degrees. We have confirmed that NH₄-N could specifically increase ¹⁵N distribution to floral tissues, change the amino acid profiles in petals which in turn bring changes to petal colors. Results with four commercially available petunia cultivars with different flower colors also validated our findings. This study has been designed to specifically investigate effects of ammonium or nitrate as the sole source of inorganic N on the developmental and chemical features of floral tissues in <italic>Petunia</italic>.

The effect of NH4+ on phosphoenolpyruvate carboxykinase gene expression, metabolic flux and citrate content of citrus juice sacs

Citrate is one of the most important metabolites determining the flavour of citrus fruit. It has been reported that nitrogen supply may have an impact on acid level of fruit. Here, the relationship between nitrogen metabolism and citrate catabolism was studied in pumelo juice sacs. Differences in metabolites, gene expression and flux distributions were analyzed in juice sacs incubated in medium with and without NH4+. Compared with those incubated with NH4+, juice sacs under nitrogen deficiency exhibited enhanced flux through phosphoenolpyruvate carboxykinase (PEPCK) and accelerated consumption of citrate, while the other two TCA cycle efflux points, through malic enzyme (ME) and glutamate dehydrogenase (GDH), were both repressed. Consistent with the estimated fluxes, the expression of PEPCK1 was upregulated under nitrogen deficiency, while that of GDH1, GDH2, NAD-ME1 and NADP-ME2 were all repressed. Thus, we propose that PEPCK1 contributes to citrate degradation under nitrogen limitation.

Effects of NH&lt;sub&gt;4&lt;/sub&gt;Cl and MgCl&lt;sub&gt;2&lt;/sub&gt; on Heat Treatment and Evaluation of Decay Resistance Given to Heat-treated Wood

Effects of NH&lt;sub&gt;4&lt;/sub&gt;Cl and MgCl&lt;sub&gt;2&lt;/sub&gt; on Heat Treatment and Evaluation of Decay Resistance Given to Heat-treated Wood

Magnesium Ion Storage Properties in a Layered (NH4)2V6O16·1.5H2O Nanobelt Cathode Material Activated by Lattice Water.

Magnesium ion batteries have attracted increasing attention as a promising energy storage device due to the high safety, high volumetric capacity, and low cost of Mg. However, the strong Coulombic interactions between Mg2+ ions and cathode materials seriously hinder the electrochemical performance of the batteries. To seek a promising cathode material for magnesium ion batteries, in this work, (NH4)2V6O16·1.5H2O and water-free (NH4)2V6O16 materials are synthesized by a one-step hydrothermal method. The effects of NH4+ and lattice water on the Mg2+ storage properties in these kinds of layered cathode materials are investigated by experiments and first-principles calculations. Lattice water is demonstrated to be of vital importance for Mg2+ storage, which not only stabilizes the layered structure of (NH4)2V6O16·1.5H2O but also promotes the transport kinetics of Mg2+. Electrochemical experiments of (NH4)2V6O16·1.5H2O show a specific capacity of 100 mA·h·g-1 with an average discharge voltage of 2.16 V vs Mg2+/Mg, highlighting the potential of (NH4)2V6O16·1.5H2O as a high-voltage cathode material for magnesium ion batteries.

Ammonium-nitrogen addition at the seedling stage does not reduce grain cadmium concentration in two common wheat (Triticum aestivum L.) cultivars

High cadmium (Cd) concentration in common wheat (Triticum aestivum L.) grains poses potential health risks. Several management strategies have been used to reduce grain Cd concentration. However, limited information is available on the use of ammonium-nitrogen (NH4+-N) as a strategy to manage Cd concentration in wheat grains. In this study, NH4+-N addition at the seedling stage unchanged the grain Cd concentration in the high-Cd accumulator, Zhoumai 18 (ZM18), but dramatically increased that in the low-Cd accumulator, Yunmai 51 (YM51). Further analysis revealed that the effects of NH4+-N addition on whole-plant Cd absorption, root-to-shoot Cd translocation, and shoot-to-grain Cd remobilization were different between the two wheat cultivars. In ZM18, NH4+-N addition did not change whole-plant Cd absorption, but inhibited root-to-shoot Cd translocation and Cd remobilization from lower internodes, lower leaves, node 1, and internode 1 to grains via the down-regulation of yellow stripe-like transporters (YSL), zinc transporters (ZIP5, ZIP7, and ZIP10), and heavy-metal transporting ATPases (HMA2). This inhibition decreased the grain Cd content by 29.62%, which was consistent with the decrease of the grain dry weight by 23.26%, leading to unchanged grain Cd concentration in ZM18. However, in YM51, NH4+-N addition promoted continuous Cd absorption during grain filling, root-to-shoot Cd translocation and whole-plant Cd absorption. The absorbed Cd was directly transported to internode 1 via the xylem and then re-transported to grains via the phloem by up-regulated YSL, ZIP5, and copper transporters (COPT4). This promotion increased the grain Cd content by 245.35%, which was higher than the increased grain dry weight by 132.89%, leading to increased grain Cd concentration in YM51. Our findings concluded that the addition of NH4+-N fertilizer at the seedling stage is not suitable for reducing grain Cd concentration in common wheat cultivars.

Ammonium transporter PsAMT1.2 from Populus simonii functions in nitrogen uptake and salt resistance

Ammonium (NH4+) is a primary nitrogen (N) source for many species, and NH4+ uptake is mediated by various transporters. However, the effects of NH4+ transporters on N uptake and metabolism under salt stress remain unclear. In the present study, we investigated the expression characteristics and transport function of PsAMT1.2 in Populus simonii and its role in ammonium uptake and metabolism under salt stress. PsAMT1.2 was localized in the plasma membrane highly expressed in the roots. Heterologous functionality tests demonstrated that PsAMT1.2 mediates NH4+ permeation across the plasma membrane in yeast mutants, restoring growth. A short-term NH4+ uptake experiment showed that PsAMT1.2 is a high-affinity NH4+ transporter with a Km value of 80.603 μM for NH4+. Compared with the wild type (WT, Populus tremula × Populus alba INRA 717-IB4 genotype), PsAMT1.2-overexpressing transgenic poplar grew better, with higher increases in stem height and relative chlorophyll content under both control and salt-stress conditions. PsAMT1.2 overexpression significantly increased the total NH4+ concentration and total N of whole plants under salt stress. The glutamate synthase (GS), glutamine synthetase (GOGAT) and glutamate dehydrogenase (GDH) activities and the total amino acids largely increased in the roots of PsAMT1.2-overexpressing transgenic plants compared with the WT plants under control conditions, suggesting that PsAMT1.2 overexpression promotes NH4+ assimilation and metabolism in poplar roots. Consistent with the increased total amino acid content, GS1.3, GS2 and Fd-GOGAT expression was upregulated in the roots and leaves of the PsAMT1.2-overexpressing transgenic plants compared with the WT plants under salt stress. Collectively, PsAMT1.2 encodes a high-affinity NH4+ transporter crucial to NH4+ uptake and metabolism under salt stress.