Recently,information acquired at the canopy top,such as spectral and textural data,has been widely used to estimate plant nitrogen(N)accumulation(PNA).The response of crops to N uptake involves not only changes in hor...Recently,information acquired at the canopy top,such as spectral and textural data,has been widely used to estimate plant nitrogen(N)accumulation(PNA).The response of crops to N uptake involves not only changes in horizontal canopy top information but also an increase in vertical plant height(PH).It remains unclear whether the fusion of spectral indices with PH can improve the estimation performance of PNA models based on spectral remote sensing across different growth stages.展开更多
Strip-till(ST),including straw mulching in the inter-row and localized fertilization in the intra-row,is a conservation tillage system for improving soil quality and crop growth.However,the yield advantage of maize un...Strip-till(ST),including straw mulching in the inter-row and localized fertilization in the intra-row,is a conservation tillage system for improving soil quality and crop growth.However,the yield advantage of maize under ST compared to conventional tillage(CT)remains unstable,and the strategies to increase maize yield under ST are unclear.This study aims to understand the physiological mechanism underlining maize yield formation under ST by comparing two maize cultivars,DKM753 and DK517,with contrasting yield performance in ST versus CT systems.Compared to CT,ST resulted in a 4.5%yield increase for DKM753 but a 5.6%decrease for DK517.These yield differences were primarily attributed to variations in grain number per ear(GN).During the rapid growth stage(V14-R3),i.e.,two weeks before and after silking,DKM753 showed a 6.7%increase in maximum growth rate(V_(max))and a 6.3%increase in average growth rate(V)under ST,whereas DK517 exhibited decline of 8.5%in V_(max) and 12.3%in V.Significant positive correlations are observed between V_(max) and V with GN under ST(R^(2)=0.79 and R^(2)=0.90,respectively).Enhanced dry matter accumulation in DKM753 under ST was attributed to increased leaf expansion rates,contributing to a larger photosynthate source.The straw mulching and localized nitrogen fertilization increased root-zone nitrogen availability at silking in ST compared to CT.DKM753 had a greater root system which made better use of the soil N and lead to an increased leaf nitrogen accumulation by 14.9%under ST.It is concluded that maize yield under the strip-till system is determined by grain number per ear,which can be increased by increasing nitrogen accumulation,plant growth,and ear development around silking stage.A sound root system can efficiently utilize soil nitrogen resources under the strip-till system,increasing plant nitrogen accumulation and thereby promoting plant growth.展开更多
Various forms of nitrogen(N)discharged by high-intensity human activities in the Yangtze River Delta are transported into the lake along the river channel,accelerating the lake’s N cycle and increasing the eutrophica...Various forms of nitrogen(N)discharged by high-intensity human activities in the Yangtze River Delta are transported into the lake along the river channel,accelerating the lake’s N cycle and increasing the eutrophication ecological risk.Taihu Lake is a typical eutrophic shallowlake,suffering fromcyanobacteria blooms for decades due to excessive exogenous nutrient load.In this study,the coupling relationship between basin N loss and lake responsewas established by combining N flow and exogenous nutrient load.The results showed striking spatiotemporal differences and the large tributaries input themajority of N.Three evolution stages of the lake ecosystem were classified,i.e.,Stage A(1980–1997)with slow increasing N load;Stage B(1998–2006)with high-level N load despite some controlling methods;Stage C(2007 to present)with the strengthening of N management in lake basin after the Water Crisis,the N load has gradually decreased,while the water flow is increasing by the year.Environmental N export in the basin was 581.46 kg/ha N in 2021,and a total of 32.06 Gg N was finally drawn into the lake.Over the recent two decades,the noticeable expansion of built-up land from 8.21%to 21.04%associated with its environmental impacts i.e.,urban heat island effect,hard pavement,and ecological fragility deserves attention.Accordingly,the rapid climate change of the basin became the key factor driving the tributaries’hydrologic conditions(r_(∂)=0.945).The developed social economy dominated the sewage discharge(r_(∂)=0.857).The N inputs and losses to the environment in the basin can be further exacerbated without control.Meanwhile,the lake would respond to the exogenous input.In addition to the self-cleaning part of the lake,the N accumulation rate of the surface sediment ranged from 3.29 to 10.77 g N/(m^(2)·yr)of Taihu Lake.To meet the pollutant control target,around 66.28 Gg anthropogenic N needs to be reduced in the upper stream area yearly.Clarifying the N flow and its environmental burden can mitigate its damage to the ecosystem and take on the refined management on the watershed scale.展开更多
Unbalanced fertilizer application with high intensity nitrogen(N)and insufficient potassium(K)results in declining soil fertility.Balanced fertilization represents an effective approach to reduce fertilizer usage whil...Unbalanced fertilizer application with high intensity nitrogen(N)and insufficient potassium(K)results in declining soil fertility.Balanced fertilization represents an effective approach to reduce fertilizer usage while enhancing maize yield and efficiency.This study examined two N levels(180 and 225 kg N ha^(-1),abbreviated N12 and N15)and four K treatments(0,75,150,and 75+75 kg K_(2)O ha^(-1),abbreviated K0,K5,K10,and K5+5)to investigate the effects of combined N and K application on biomass,nutrient accumulation,and remobilization characteristics in waxy maize.Results indicated that grain yield increased with higher K application at constant N levels,demonstrating an average increase of 1,254.8 kg ha^(-1)(2020)and 727.3 kg ha^(-1)(2021)compared with K0.Under identical N and K applications,K5+5 enhanced grain yield through increased kernel weight.The K5+5 treatment showed no significant difference in biomass and nutrient accumulation between N12 and N15.Compared to K10,K5+5 enhanced both the average remobilization amount(RBA)of biomass and increased RBA of N,phosphorus(P)and K.Additionally,the average remobilization efficiency(RBE)of biomass,N,P,and K in K5+5 increased by 3.3,4.6,10.6,and 4.2%,respectively.Moreover,topdressing K improved the apparent contribution to grain(AC)of biomass,N,P and K,facilitating greater nutrient transfer to grains and significantly increasing nutrient harvest index.Based on yield and fertilizer use efficiency,this study recommends optimized K application(basal and topdressing 75 kg ha^(-1))and moderate reduction in N application(from 225 to 180 kg ha^(-1))for spring-sown waxy maize production in southern China.展开更多
Biological nitrogen fixation(BNF)and photosynthetic carbon fixation underpin food production and climate mitigation,yet natural systems are constrained by oxygen sensitivity,high energy demand,and inefficient catalyst...Biological nitrogen fixation(BNF)and photosynthetic carbon fixation underpin food production and climate mitigation,yet natural systems are constrained by oxygen sensitivity,high energy demand,and inefficient catalysts.This review synthesizes advances that recast these processes as engineering targets and proposes a conceptual roadmap that bridges synthetic symbioses with the synthetic biology of enzymes and pathways.For BNF,progress spans cross-kingdom strategies—from refactoring nif gene sets and targeting nitrogenase assembly to eukaryotic organelles,to engineering plant-associated diazotrophs,rhizosphere control circuits,and emerging nodule-like microenvironments.For carbon assimilation,new-to-nature CO_(2)-fixation modules and photorespiratory bypasses illustrate how pathway redesign and alternative carboxylases can circumvent key Calvin–Benson–Bassham limitations,and expanding photosynthetic light capture offers additional leverage.Across these domains,we extract common design principles:(i)nitrogenase output is increasingly governed by carbon/energy supply and electron delivery as much as by oxygen protection;(ii)robust function requires compartment-aware enzyme–chassis coordination,substrate channeling,and dynamic regulation using sensors and control circuits;and(iii)scalable implementation may benefit from distributing metabolic labor across engineered consortia rather than forcing all functions into a single host.We discuss enabling technologies—including AI-guided protein design and directed evolution,cell-free prototyping,chassis toolkits,and materials/bioelectrochemical interfaces—that can accelerate design–build–test–learn cycles and reduce barriers to deployment.Together,these insights define a path toward integrated nitrogen and carbon fixation systems for low-emission agriculture and biomanufacturing.展开更多
A collection of ordered-disordered Bi_(2)WO_(6)homojunction catalysts was prepared in-situ through a facile one-step hydrothermal process,and their photocatalytic nitrogen fixation to synthesize ammonia performance wa...A collection of ordered-disordered Bi_(2)WO_(6)homojunction catalysts was prepared in-situ through a facile one-step hydrothermal process,and their photocatalytic nitrogen fixation to synthesize ammonia performance was evaluated.Results showed that ordered-disordered Bi_(2)WO_(6)(OD-2)obtained by adding 1.5 mL of ethylene glycol during preparation exhibited the optimal nitrogen fixation performance,with a nitrogen fixation rate of 114.92μmol·g^(-1)·h^(-1).However,its crystal counterpart,Bi_(2)WO_(6)(BWO),lacked nitrogen-fixation activity.In-situ diffuse reflectance-Fourier transform infrared technique(DR-FTIR),electrochemical tests,and energy band structure analysis confirmed that the surface disordered structure in OD-2 not only promoted nitrogen activation but also enabled the effective separation of photogenerated electron-hole pairs at the ordered-disordered interface,facilitating the interface electrons transfer to the surface disordered structure of OD-2 and reacting with N_(2) adsorbed on the disordered structure,thereby promoting the smooth progress of the nitrogen fixation reaction.展开更多
Lodging is a primary factor limiting rice grain yield.Achieving synergistic improvements in grain yield and nitrogen use efficiency(NUE)without increasing lodging risk has been a global research priority.In this study...Lodging is a primary factor limiting rice grain yield.Achieving synergistic improvements in grain yield and nitrogen use efficiency(NUE)without increasing lodging risk has been a global research priority.In this study,two rice cultivars-Yongyou 2640(indica–japonica hybrid rice)and Jinxiangyu 1(inbred japonica rice)-were evaluated in field experiments conducted over two growing seasons.Six nitrogen management strategies were implemented:no nitrogen(T1),conventional urea(T2),controlled-release nitrogen(CRN)(T3),reduction of CRN(T4),CRN combined with single basal application of conventional urea(T5),and CRN combined with split applications of conventional urea(T6).Compared with T2,the integrated nitrogen strategies(T5 and T6)increased NUE by 4.89–5.69%and grain yield by 3.41–4.65%.These treatments also enhanced structural integrity of the second basal internode,evidenced by increased carbohydrate content,internode breaking strength,epidermal silicon layer thickness,number of large and small vascular bundles,and thickness of both parenchymatous and mechanical tissues.Concurrently,internode length,bending moment,and lodging index were reduced.Collectively,these findings indicate that integrating CRN with conventional urea improves morphological,mechanical,physicochemical,and anatomical properties of the second basal internode,thereby enhancing stem strength and enabling high yield and NUE without compromising lodging resistance.展开更多
A novel salt-tolerant aerobic denitrifying bacterium,Marinobacter sp.strain B108,was isolated from a marine recirculating aquaculture system(MRAS).The optimal aerobic denitrification parameters were CH_(3)COONa as car...A novel salt-tolerant aerobic denitrifying bacterium,Marinobacter sp.strain B108,was isolated from a marine recirculating aquaculture system(MRAS).The optimal aerobic denitrification parameters were CH_(3)COONa as carbon source,pH of 8,C/N of16,temperature of 35°C,dissolved oxygen(DO)of 6 mg/L and salinity of 30.Under these optimal conditions,Marinobacter sp.strain B108 had a removal efficiency of 100%for N O_(3)^(-)-N and 98.89%for total nitrogen(TN)within 24 h.The nitrate removal pathways of Marinobacter sp.strain B108 were included by the assimilative reduction pathway(N O_(3)^(-)-N→biomass N)and the dissimilatory reduction pathway(N O_(3)^(-)-N→N_(2))of aerobic denitrification,and lack of dissimilatory reduction to ammonium pathway(N O_(3)^(-)-N→N H_(4)^(+)-N).The nitrogen removal process of Marinobacter sp.strain B108 was mainly contributed by the dissimilatory reduction pathway.The kinetic parameters for N O_(3)^(-)-N and N O_(2)^(-)-N removal were determined as V_(m)of 971.566 and 165.336 mg/(gDCW·L·h),and K_(m)of 22.74 and 31.68 mg/L,respectively.This work reflects the practical application potential of Marinobacter sp.strain B108for nitrogen removal in MRAS.展开更多
Amid accelerating global land degradation,establishing high-efficiency ecological restoration principles and frameworks is crucial.Here,we explore the application of threshold effects in the ecological restoration pro...Amid accelerating global land degradation,establishing high-efficiency ecological restoration principles and frameworks is crucial.Here,we explore the application of threshold effects in the ecological restoration process based on field experiments and globally available experimental data from 173 sites.Combining data integration analysis and meta-analysis,we collectively verified the universality of threshold effects in grasslands.The global grasslands’average nitrogen application threshold is 3.78 g·m^(-2)·yr^(−1),while the threshold value of degraded grassland(3.65 g·m^(-2)·yr^(−1))is lower than that of nondegraded grassland(5.90 g·m^(-2)·yr^(−1)).The low nitrogen-driven thresholds are affected by degradation status,climate(precipitation and temperature),and other site conditions,but not fertilization forms.Independent experiments further demonstrated that an increase in soil moisture content can lead to the disappearance of nitrogen threshold effects,revealing that ecological threshold effects are influenced by ecosystem stress factors.Following the significant increase in plant biomass triggered by the nitrogen threshold,the ecosystem undergoes systemic improvement.Soil organic carbon,urease activity,soil microbial diversity,and other soil properties are significantly enhanced.Soil nitrogen cycle-related microbial communities and soil physicochemical attributes are significantly activated.The results indicate that a threshold response pattern may develop before nitrogen saturation is reached,and low nitrogen input can boost productivity and improve the plant-soil-microbe system.Our findings reveal a nonprogressive path of restoration in degraded ecosystems,and thus,restoration based on threshold effects can offer an efficient and safe solution to combat ecological degradation.展开更多
Nitrogen-containing structures represent a significant branch exhibiting remarkable biological activity,surpassing non-nitrogen architectures.Given the vast array of nitrogen-containing compounds and their crucial rol...Nitrogen-containing structures represent a significant branch exhibiting remarkable biological activity,surpassing non-nitrogen architectures.Given the vast array of nitrogen-containing compounds and their crucial role in the pharmaceutical industry,chemists have been motivated to devise efficient,cost-effective,and practical methods for C-N bond formation.Significant advancements have been achieved in this cutting-edge field over the past few decades.This review aims to encapsulate the latest progress in C-N bond formation via the photocatalytic C-H amination process.Initially,we provide a comprehensive introduction to C-H amination transformations.Subsequently,we categorize these photochemical conversions into two parts:intramolecular and intermolecular C-H amination.To elucidate the underlying principles of specific illustrative examples,we have carefully chosen and elaborated on the reaction mechanisms,representative experimental outcomes,and applications.展开更多
Ecological floating bed is an important biological remediation method for water pollution control.During the removal of excess nutrients and pollutants,changes in environmental factors affect the characteristics of mi...Ecological floating bed is an important biological remediation method for water pollution control.During the removal of excess nutrients and pollutants,changes in environmental factors affect the characteristics of microorganisms in aquatic ecosystems.To understand the influences of ecological floating beds on size-fractionated microorganisms,we investigated the community assembly and nitrogen metabolic characteristics of three size-fractionated microorganism groups in the ecological floating bed area,using 18S rDNA,16S rDNA metabarcoding,and metagenomic sequencing techniques.Firstly,we discovered substantial differences between size-fractionated groups in the diversity and compositions of both microeukaryotic and bacterial communities,as well as the influences of floating beds on specific groups.The floating beds appeared to provide more habitats for heterotrophs and symbiotes while potentially inhibiting the growth of certain phytoplankton(cyanobacteria).Secondly,we observed that microeukaryotic and bacterial communities were predominantly influenced by stochastic and deterministic processes,respectively,and they both exhibited distinct patterns across different size-fractionated groups.Notably,microeukaryotic community assembly demonstrated a greater sensitivity to ecological floating beds,as indicated by an increase in dispersal limitation processes.Finally,the nitrogen metabolism functional genes revealed that microbes associated with large-sized particles played a crucial role in dissimilatory nitrate reduction to ammonium(DNRA)and denitrification processes within the floating bed area,thereby facilitating the removal of excess nitrogen nutrients from the water.In contrast,freeliving microorganisms from small-sized groups were linked mainly to the genes involved in nitrogen assimilation and assimilatory nitrate reduction to ammonium(ANRA)processes.These findings help understand the impact of ecological floating beds on the diversity and functional characteristics of microorganism communities in different size-fractionated groups.展开更多
The zigzag nitrogen chain,similar to the Ch-N structure,has long been considered as a potential high-energy-density structure.However,all the previously predicted zigzag N-chain structures,similar to Ch-N,exhibited im...The zigzag nitrogen chain,similar to the Ch-N structure,has long been considered as a potential high-energy-density structure.However,all the previously predicted zigzag N-chain structures,similar to Ch-N,exhibited imaginary frequencies in their phonon spectra at 0 GPa.Here,we conducted a systematic investigation of P-N compounds using first-principles calculations,uncovering a series of structurally similar stable phases,C2/m-PN_(x)(x=6,8,10,12,and 14),in which N forms zigzag N chains similar to those in Ch-N.In P-N compounds,the longest zigzag N-chain,which can theoretically remain stable under ambient pressure,is the N-chain composed of 14 N atoms in C2/m-PN14.If the N-chain continues to grow,imaginary interchain vibrational frequencies arise in the system.Notably,N chains with an even number of atoms were more likely to be energetically favorable.The five C2/m-PN_(x) phases and one metastable phase(R-PN_(6))exhibited remarkable stability and excellent detonability at ambient pressure,indicating that they are promising candidates for high-energy-density materials.In addition,R-PN_(6) was the first structure to stabilize the N_(6) ring through covalent bonding,with the covalent network contributing to its high hardness(47.59 GPa).展开更多
A systematic investigation was conducted on the influence of residual nitrogen(0.003–0.008 wt.%)on the microstructure,mechanical properties,and strain aging behavior of scrap-electric arc furnace produced SAPH440 low...A systematic investigation was conducted on the influence of residual nitrogen(0.003–0.008 wt.%)on the microstructure,mechanical properties,and strain aging behavior of scrap-electric arc furnace produced SAPH440 low-alloy steel.Through internal friction spectroscopy,transmission electron microscopy,and atom probe tomography,the occurrence state of nitrogen and its interaction with dislocations under simulated industrial pre-strain(2%,10%)and aging conditions(250°C/h)were elucidated.Increasing nitrogen content was found to refine ferrite grain size and enhance strength,but it also drastically reduced ductility and impact toughness due to heightened strain aging sensitivity.Nitrogen levels≥0.008 wt.%promoted extensive Cottrell atmosphere formation,which pinned dislocations and caused severe embrittlement after aging,leading to additional yield strength increments of up to 147 MPa(2%strain)and 164 MPa(10%strain),while elongation fell below 16%and 8.3%,respectively.Critically,even 2%pre-strain immobilized virtually all nitrogen atoms≤0.008 wt.%,precipitating significant property degradation.Nitrogen segregation at grain boundaries and dislocation networks after strain aging was directly observed.展开更多
[Objectives]To investigate the effects of different planting densities and nitrogen application rates on the yield and quality of the tobacco cultivar Chuxue 80.[Methods]A field experiment was conducted in Hubei Provi...[Objectives]To investigate the effects of different planting densities and nitrogen application rates on the yield and quality of the tobacco cultivar Chuxue 80.[Methods]A field experiment was conducted in Hubei Province,evaluating various combinations of planting density and nitrogen rate for Chuxue 80.[Results]At the maturity stage,the TN1 treatment(5 kg N per 667 m^(2) with a density of 1900 plants per 667 m^(2))demonstrated the most favorable agronomic performance.The TN9 treatment(11 kg N per 667 m^(2) with a density of 1110 plants per 667 m^(2))achieved the highest wrapper tobacco yield and output value.Meanwhile,the TN5 treatment(8 kg N per 667 m^(2) with a density of 1515 plants per 667 m^(2))resulted in the best smoking quality.[Conclusions]The TN9 treatment,with a planting density of 1110 plants per 667 m^(2) and a nitrogen application rate of 11 kg per 667 m^(2),is recommended as the optimal cultivation practice for Chuxue 80 in Hubei Province.展开更多
The establishment of plantations has become a critical approach for reducing greenhouse gas emissions,particularly in fragile environments with carbon sequestration potential.In karst areas,plantations based on fastgr...The establishment of plantations has become a critical approach for reducing greenhouse gas emissions,particularly in fragile environments with carbon sequestration potential.In karst areas,plantations based on fastgrowing afforestation species made significant contributions to enhancing carbon sequestration.However,the impact of understory vegetation on carbon accumulation remains unclear.Especially,the carbon accumulation associated with litter produced during the replacement of understory species receives insufficient attention,which leads to the neglect of the carbon sequestration potential in plantations of karst areas.Leaf is a crucial organ that links the litter production.To explore how leaf traits adapt to competitive environments and drive litter carbon accumulation during understory species replacement,this study observed leaf traits and litter carbon content changes in three types of plantations in the Liujiang River Basin,a typical karst area.A total of 37 sampling plots were selected for field investigation over a twoyear period.Leaf traits,species diversity,vegetation coverage,and litter carbon characteristics in understory vegetation were measured.Variance analysis,allometric equations,and path analysis were used for data analysis.The results showed that most understory species adopted a biomass conservation strategy under high-coverage conditions(>44.27%)and expanded competitive leaf area under low-coverage conditions(<44.27%).However,Bidens pilosa and Miscanthus floridulus exhibited strong competitiveness during understory species replacement.They showed an expansion of competitive leaf area under high-coverage conditions.This competitive strategy reduced species diversity and community specific leaf area.But the rapid expansion of Bidens pilosa and Miscanthus floridulus increased understory vegetation coverage,and their increased specific leaf area facilitated leaf shedding,resulting in significant litter weight accumulation(P<0.05),thereby enhancing litter carbon content per unit area.These competitive strategies were key driving factors for the increase in litter carbon content per square meter,which reached a maximum of 49.6% higher than that in natural grasslands.And the maximum increase in litter carbon accumulation derived from understory vegetation reached 3.37 times from 2023 to 2024 in plantations.In the understory vegetation of plantations,the competitive strategies reflected by leaf adaptation of key competitive species are critical factors influencing litter carbon accumulation.Future research could deeply explore the carbon sequestration effects resulting from the dynamic changes in competition within the understory vegetation of plantations.展开更多
Climate warming and atmospheric nitrogen(N)deposition have profound influences on the terrestrial biosphere.However,how these two global change drivers affect phytoplankton which are important primary producers in wet...Climate warming and atmospheric nitrogen(N)deposition have profound influences on the terrestrial biosphere.However,how these two global change drivers affect phytoplankton which are important primary producers in wetlands with large carbon stocks and complex hydrological fluctuations remain largely unclear.As part of a two-year field experiment in a freshwater wetland,this study was conducted to investigate the effects of nighttime warming and N addition on phytoplankton biomass in the North China Plain.The results showed that neither nighttime warming nor N addition influenced the Shannon-Wiener index of phytoplankton community.Nighttime warming did not change phytoplankton biomass,likely due to the different warming impacts on dominant phyla and in different seasons.Decreased phytoplankton biomass in spring because of the increased water pH and submerged plant coverage was compensated by the enhanced biomass in autumn due to the reduced dissolved oxygen and submerged plant coverage,leading to the neutral change of phytoplankton biomass under warming.Nitrogen addition elevated phytoplankton biomass by 11.6%,which could be attributed to the enhanced nutrient availability and reduced submerged plant coverage.Positive relationships of methane(CH4)emission rates at the water-air interface with phytoplankton biomass indicated the potentially crucial role of phytoplankton in mediating wetland CH4 cycling through photosynthesis-driven metabolisms.The findings suggested the seasonal variation of phytoplankton and their potential responses to nighttime warming and N deposition,which may provide a more accurate basis for assessing the global change-carbon feedback in wetland ecosystems.展开更多
Reservoir is an important source of CO_(2) emissions.The backwater bay is a distinct hydrological unit formed in the open channel of canyon-reservoir as a result of impoundment.It is characterized by efficient nutrien...Reservoir is an important source of CO_(2) emissions.The backwater bay is a distinct hydrological unit formed in the open channel of canyon-reservoir as a result of impoundment.It is characterized by efficient nutrients retention and a propensity for frequent eutrophication.However,the spatio-temporal dynamics of CO_(2) emissions in these backwater bays remain unclear.This study investigated CO_(2) fluxes(fCO_(2))in two different backwater bays(Hanfeng Lake and Gaoyang Lake)within the Three Gorges Reservoir(TGR),to reveal the spatio-temporal dynamics and driving factors of CO_(2) emissions.The two backwater bays serve as minor sources of CO_(2) emissions,exhibiting lower fCO_(2) compared to other water areas within the TGR.In the subsiding and low water level periods of the TGR,the fCO_(2) in the two backwater bays were significantly lower,with some areas even converting into CO_(2) sinks due to extensive eutrophication.However,the water flow backward caused by the TGR water level elevation simultaneously enhances CO_(2) emissions by diluting algae density and constraining primary production.We highlighted that nutrients enrichment,eutrophication,and water level fluctuations co-dominate the temporal dynamics of CO_(2) emissions from backwater bays in the TGR.The CO_(2) fluxes decreased from upstream to downstream in the two backwater bays.The spatial distribution of nutrients and related algal density are critical factors driving this pattern.The key factors influencing CO_(2) emissions in the backwater bays diversified with water level fluctuations.Our findings contribute to a better understanding of CO_(2) emissions in large reservoirs with varying hydrological habitats.展开更多
Legume-based intercropping enhances asymbiotic biological nitrogen fixation(BNF);however,the underlying mechanisms remain unclear,including the roles of soil keystone diazotroph taxa with varying niche breadths.A fiel...Legume-based intercropping enhances asymbiotic biological nitrogen fixation(BNF);however,the underlying mechanisms remain unclear,including the roles of soil keystone diazotroph taxa with varying niche breadths.A field experiment was conducted to evaluate soil BNF variations between rhizosphere and bulk soils in peanut/cotton intercropping systems and monocultures.BNF activities were measured by nitrogen fixation rates,nitrogenase activity,and nifH gene abundance.Phylogenetic null models,co-occurrence networks,and niche breadth analysis were applied to investigate the roles of diazotrophic keystone taxa and their ecological niches.Rhizosphere soils exhibited 7.8–125.5%higher BNF potentials than bulk soils,whereas intercropping systems showed 11.6–323.0%increases over monocultures for nitrogen fixation rate,nitrogenase activity,and nifH gene abundance(all P<0.05).Diazotrophic community composition and diversity differed significantly,with Proteobacteria(excluding Alphaproteobacteria)enriched in intercropping and rhizosphere soils,while Cyanobacteria and Firmicutes were less abundant.Deterministic processes,particularly heterogeneous selection,dominated community assembly in the rhizosphere(91.9%)and intercropping soils(86.3%).The co-occurrence networks consistently revealed more complex and interconnected communities in intercropping and rhizosphere soils that were dominated by opportunistic diazotrophs(78.8–85.9%),followed by specialists(10.2–18.5%)and generalists(1.38–3.80%).Keystone taxa,including opportunists such as Azoarcus,Azohydromonas,and Steroidobacter,and generalists like Pseudomonas and Azotobacter,correlated positively with microbial biomass carbon and nitrate nitrogen,contributing to enhanced BNF.Peanut/cotton intercropping enhances BNF by selectively enriching the keystone diazotrophic taxa with varying ecological roles,particularly opportunists and generalists.Such targeted intercropping strategies can optimize BNF,improve soil fertility,and promote sustainable agricultural production.展开更多
Cellulose,the most abundant and renewable biopolymer,offers a sustainable and cost-effective solution for regulating lithium electrodeposition toward safer lithium metal batteries,thanks to its high nanofibrous struct...Cellulose,the most abundant and renewable biopolymer,offers a sustainable and cost-effective solution for regulating lithium electrodeposition toward safer lithium metal batteries,thanks to its high nanofibrous structure and intrinsic lithiophilic property.In this work,we introduce interface-engineered cellulose-based separators by converting intrinsic hydroxyl groups on cellulose nanofibers(CNFs)to nitrogen functionalities through a trace conducting polymer coating.Both experimental and theoretical results reveal that the nitrogen moieties disrupt the compact hydrogen bond network within hydroxyl cellulose,enabling multiple nitrogen-lithium interactions that enhance lithium ion transport.In addition to an extraordinary Li^(+)transference number of 0.86 and a high ionic conductivity of 1.1 mS cm^(-1),the nitrogen-functionalized CNF contributes to a uniform electric field and Li^(+)concentration distribution across the lithium metal surface.This facilitates the formation of a LiF-rich solid electrolyte interface and suppresses Li dendrite growth.Consequently,Li‖Li cells demonstrate stable plating/stripping cycles for approximately 3000 h at a current density of 1 mA cm^(-2) with a fixed capacity of 1 mAh cm^(-2),while maintaining a low overpotential of 15 mV.Our work provides valuable insights into the surface functionalization of natural biomass for advancing sustainable energy storage technologies.展开更多
Highlights OsCAX2 is localized to tonoplast,and cadmium induces its expression.OsCAX2 overexpression reduces cadmium concentration in indica rice grains by 49.1%.Cadmium(Cd)exposure poses significant health risks to h...Highlights OsCAX2 is localized to tonoplast,and cadmium induces its expression.OsCAX2 overexpression reduces cadmium concentration in indica rice grains by 49.1%.Cadmium(Cd)exposure poses significant health risks to humans,and the International Agency for Research on Cancer has classified it as a Group I carcinogen.Cadmium undergoes minimal metabolism in the human body;consequently,prolonged Cd^(2+)exposure can cause severe damage to multiple organs including the liver,kidneys,lungs,bones,and immune system(Shao et al.2024).Rice,one of the three global staple crops,and Cd exposure in humans primarily occurs the consumption of contaminated rice grains.The contribution of rice to the total dietary Cd intake is over 50% for non-smoking Asian populations(Chen et al.2018;Shi et al.2020).展开更多
基金supported by the National Key Research and Development Plan Project Sub-Topic of China(Grant Nos.2022YFD1901500 and 2022YFD1901505-07)the National Natural Science Foundation of China(Grant No.32260531)+1 种基金the Key Laboratory of Molecular Breeding for Grain and Oil Crops in Guizhou Province,China(Grant No.Qiankehezhongyindi[2023]8)the Key Laboratory of Functional Agriculture of Guizhou Provincial Higher Education Institutions,China(Grant No.Qianjiaoji[2023]007).
文摘Recently,information acquired at the canopy top,such as spectral and textural data,has been widely used to estimate plant nitrogen(N)accumulation(PNA).The response of crops to N uptake involves not only changes in horizontal canopy top information but also an increase in vertical plant height(PH).It remains unclear whether the fusion of spectral indices with PH can improve the estimation performance of PNA models based on spectral remote sensing across different growth stages.
基金the National Key Research and Development Program of China(2022YFD1500705)National Natural Science Foundation of China(U19A2035)for financial support。
文摘Strip-till(ST),including straw mulching in the inter-row and localized fertilization in the intra-row,is a conservation tillage system for improving soil quality and crop growth.However,the yield advantage of maize under ST compared to conventional tillage(CT)remains unstable,and the strategies to increase maize yield under ST are unclear.This study aims to understand the physiological mechanism underlining maize yield formation under ST by comparing two maize cultivars,DKM753 and DK517,with contrasting yield performance in ST versus CT systems.Compared to CT,ST resulted in a 4.5%yield increase for DKM753 but a 5.6%decrease for DK517.These yield differences were primarily attributed to variations in grain number per ear(GN).During the rapid growth stage(V14-R3),i.e.,two weeks before and after silking,DKM753 showed a 6.7%increase in maximum growth rate(V_(max))and a 6.3%increase in average growth rate(V)under ST,whereas DK517 exhibited decline of 8.5%in V_(max) and 12.3%in V.Significant positive correlations are observed between V_(max) and V with GN under ST(R^(2)=0.79 and R^(2)=0.90,respectively).Enhanced dry matter accumulation in DKM753 under ST was attributed to increased leaf expansion rates,contributing to a larger photosynthate source.The straw mulching and localized nitrogen fertilization increased root-zone nitrogen availability at silking in ST compared to CT.DKM753 had a greater root system which made better use of the soil N and lead to an increased leaf nitrogen accumulation by 14.9%under ST.It is concluded that maize yield under the strip-till system is determined by grain number per ear,which can be increased by increasing nitrogen accumulation,plant growth,and ear development around silking stage.A sound root system can efficiently utilize soil nitrogen resources under the strip-till system,increasing plant nitrogen accumulation and thereby promoting plant growth.
基金supported by the National Key Research and Development Program of China(No.2021YFC3201502)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX24_1830).
文摘Various forms of nitrogen(N)discharged by high-intensity human activities in the Yangtze River Delta are transported into the lake along the river channel,accelerating the lake’s N cycle and increasing the eutrophication ecological risk.Taihu Lake is a typical eutrophic shallowlake,suffering fromcyanobacteria blooms for decades due to excessive exogenous nutrient load.In this study,the coupling relationship between basin N loss and lake responsewas established by combining N flow and exogenous nutrient load.The results showed striking spatiotemporal differences and the large tributaries input themajority of N.Three evolution stages of the lake ecosystem were classified,i.e.,Stage A(1980–1997)with slow increasing N load;Stage B(1998–2006)with high-level N load despite some controlling methods;Stage C(2007 to present)with the strengthening of N management in lake basin after the Water Crisis,the N load has gradually decreased,while the water flow is increasing by the year.Environmental N export in the basin was 581.46 kg/ha N in 2021,and a total of 32.06 Gg N was finally drawn into the lake.Over the recent two decades,the noticeable expansion of built-up land from 8.21%to 21.04%associated with its environmental impacts i.e.,urban heat island effect,hard pavement,and ecological fragility deserves attention.Accordingly,the rapid climate change of the basin became the key factor driving the tributaries’hydrologic conditions(r_(∂)=0.945).The developed social economy dominated the sewage discharge(r_(∂)=0.857).The N inputs and losses to the environment in the basin can be further exacerbated without control.Meanwhile,the lake would respond to the exogenous input.In addition to the self-cleaning part of the lake,the N accumulation rate of the surface sediment ranged from 3.29 to 10.77 g N/(m^(2)·yr)of Taihu Lake.To meet the pollutant control target,around 66.28 Gg anthropogenic N needs to be reduced in the upper stream area yearly.Clarifying the N flow and its environmental burden can mitigate its damage to the ecosystem and take on the refined management on the watershed scale.
基金the financial support of the Jiangsu Agricultural Industry Technology System of China(JATS[2022]497)the Jiangsu Agriculture Science and Technology Innovation Fund,China(CX[23]3117)+2 种基金the Key Research&Development Program of Jiangsu Province,China(BE2021317)the National Natural Science Foundation of China(32101828)the Priority Academic Program Development of Jiangsu Higher Education Institutions,China(PAPD)。
文摘Unbalanced fertilizer application with high intensity nitrogen(N)and insufficient potassium(K)results in declining soil fertility.Balanced fertilization represents an effective approach to reduce fertilizer usage while enhancing maize yield and efficiency.This study examined two N levels(180 and 225 kg N ha^(-1),abbreviated N12 and N15)and four K treatments(0,75,150,and 75+75 kg K_(2)O ha^(-1),abbreviated K0,K5,K10,and K5+5)to investigate the effects of combined N and K application on biomass,nutrient accumulation,and remobilization characteristics in waxy maize.Results indicated that grain yield increased with higher K application at constant N levels,demonstrating an average increase of 1,254.8 kg ha^(-1)(2020)and 727.3 kg ha^(-1)(2021)compared with K0.Under identical N and K applications,K5+5 enhanced grain yield through increased kernel weight.The K5+5 treatment showed no significant difference in biomass and nutrient accumulation between N12 and N15.Compared to K10,K5+5 enhanced both the average remobilization amount(RBA)of biomass and increased RBA of N,phosphorus(P)and K.Additionally,the average remobilization efficiency(RBE)of biomass,N,P,and K in K5+5 increased by 3.3,4.6,10.6,and 4.2%,respectively.Moreover,topdressing K improved the apparent contribution to grain(AC)of biomass,N,P and K,facilitating greater nutrient transfer to grains and significantly increasing nutrient harvest index.Based on yield and fertilizer use efficiency,this study recommends optimized K application(basal and topdressing 75 kg ha^(-1))and moderate reduction in N application(from 225 to 180 kg ha^(-1))for spring-sown waxy maize production in southern China.
基金supported by the funds of the Ministry of Science and Technology of China(2019YFA0904700)the National Natural Science Foundation of China(32471477)to Cheng Qi.
文摘Biological nitrogen fixation(BNF)and photosynthetic carbon fixation underpin food production and climate mitigation,yet natural systems are constrained by oxygen sensitivity,high energy demand,and inefficient catalysts.This review synthesizes advances that recast these processes as engineering targets and proposes a conceptual roadmap that bridges synthetic symbioses with the synthetic biology of enzymes and pathways.For BNF,progress spans cross-kingdom strategies—from refactoring nif gene sets and targeting nitrogenase assembly to eukaryotic organelles,to engineering plant-associated diazotrophs,rhizosphere control circuits,and emerging nodule-like microenvironments.For carbon assimilation,new-to-nature CO_(2)-fixation modules and photorespiratory bypasses illustrate how pathway redesign and alternative carboxylases can circumvent key Calvin–Benson–Bassham limitations,and expanding photosynthetic light capture offers additional leverage.Across these domains,we extract common design principles:(i)nitrogenase output is increasingly governed by carbon/energy supply and electron delivery as much as by oxygen protection;(ii)robust function requires compartment-aware enzyme–chassis coordination,substrate channeling,and dynamic regulation using sensors and control circuits;and(iii)scalable implementation may benefit from distributing metabolic labor across engineered consortia rather than forcing all functions into a single host.We discuss enabling technologies—including AI-guided protein design and directed evolution,cell-free prototyping,chassis toolkits,and materials/bioelectrochemical interfaces—that can accelerate design–build–test–learn cycles and reduce barriers to deployment.Together,these insights define a path toward integrated nitrogen and carbon fixation systems for low-emission agriculture and biomanufacturing.
文摘A collection of ordered-disordered Bi_(2)WO_(6)homojunction catalysts was prepared in-situ through a facile one-step hydrothermal process,and their photocatalytic nitrogen fixation to synthesize ammonia performance was evaluated.Results showed that ordered-disordered Bi_(2)WO_(6)(OD-2)obtained by adding 1.5 mL of ethylene glycol during preparation exhibited the optimal nitrogen fixation performance,with a nitrogen fixation rate of 114.92μmol·g^(-1)·h^(-1).However,its crystal counterpart,Bi_(2)WO_(6)(BWO),lacked nitrogen-fixation activity.In-situ diffuse reflectance-Fourier transform infrared technique(DR-FTIR),electrochemical tests,and energy band structure analysis confirmed that the surface disordered structure in OD-2 not only promoted nitrogen activation but also enabled the effective separation of photogenerated electron-hole pairs at the ordered-disordered interface,facilitating the interface electrons transfer to the surface disordered structure of OD-2 and reacting with N_(2) adsorbed on the disordered structure,thereby promoting the smooth progress of the nitrogen fixation reaction.
基金supported by the National Key Research and Development Program of China(2022YFD2300304)the National Natural Science Foundation of China(32272197 and 32071944)+2 种基金the Hong Kong Research Grants Council,China(GRF 14177617,12103219,12103220,and AoE/M-403/16)the State Key Laboratory of Agrobiotechnology(Strategic Collaborative Projects)at the Chinese University of Hong Kong,Chinathe Priority Academic Program Development of Jiangsu Higher Education Institutions,China(PAPD)。
文摘Lodging is a primary factor limiting rice grain yield.Achieving synergistic improvements in grain yield and nitrogen use efficiency(NUE)without increasing lodging risk has been a global research priority.In this study,two rice cultivars-Yongyou 2640(indica–japonica hybrid rice)and Jinxiangyu 1(inbred japonica rice)-were evaluated in field experiments conducted over two growing seasons.Six nitrogen management strategies were implemented:no nitrogen(T1),conventional urea(T2),controlled-release nitrogen(CRN)(T3),reduction of CRN(T4),CRN combined with single basal application of conventional urea(T5),and CRN combined with split applications of conventional urea(T6).Compared with T2,the integrated nitrogen strategies(T5 and T6)increased NUE by 4.89–5.69%and grain yield by 3.41–4.65%.These treatments also enhanced structural integrity of the second basal internode,evidenced by increased carbohydrate content,internode breaking strength,epidermal silicon layer thickness,number of large and small vascular bundles,and thickness of both parenchymatous and mechanical tissues.Concurrently,internode length,bending moment,and lodging index were reduced.Collectively,these findings indicate that integrating CRN with conventional urea improves morphological,mechanical,physicochemical,and anatomical properties of the second basal internode,thereby enhancing stem strength and enabling high yield and NUE without compromising lodging resistance.
基金National Natural Science Foundation of China(No.51978636)。
文摘A novel salt-tolerant aerobic denitrifying bacterium,Marinobacter sp.strain B108,was isolated from a marine recirculating aquaculture system(MRAS).The optimal aerobic denitrification parameters were CH_(3)COONa as carbon source,pH of 8,C/N of16,temperature of 35°C,dissolved oxygen(DO)of 6 mg/L and salinity of 30.Under these optimal conditions,Marinobacter sp.strain B108 had a removal efficiency of 100%for N O_(3)^(-)-N and 98.89%for total nitrogen(TN)within 24 h.The nitrate removal pathways of Marinobacter sp.strain B108 were included by the assimilative reduction pathway(N O_(3)^(-)-N→biomass N)and the dissimilatory reduction pathway(N O_(3)^(-)-N→N_(2))of aerobic denitrification,and lack of dissimilatory reduction to ammonium pathway(N O_(3)^(-)-N→N H_(4)^(+)-N).The nitrogen removal process of Marinobacter sp.strain B108 was mainly contributed by the dissimilatory reduction pathway.The kinetic parameters for N O_(3)^(-)-N and N O_(2)^(-)-N removal were determined as V_(m)of 971.566 and 165.336 mg/(gDCW·L·h),and K_(m)of 22.74 and 31.68 mg/L,respectively.This work reflects the practical application potential of Marinobacter sp.strain B108for nitrogen removal in MRAS.
基金supported by the Major Special Projects of the National Natural Science Foundation of China(Grants No.52374170 and 42377465)the Third Comprehensive Scientific Exploration in Xinjiang(Grant No.2022xjkk1005)+1 种基金the Special Technology Innovation Fund of Carbon Peak and Carbon Neutrality in Jiangsu Province(Grant No.BK20231515)the Shaanxi Shenmu Natural Field Observation and Research Station of Erosion and Environment,which provided the site and data on experimental conditions for field trials.
文摘Amid accelerating global land degradation,establishing high-efficiency ecological restoration principles and frameworks is crucial.Here,we explore the application of threshold effects in the ecological restoration process based on field experiments and globally available experimental data from 173 sites.Combining data integration analysis and meta-analysis,we collectively verified the universality of threshold effects in grasslands.The global grasslands’average nitrogen application threshold is 3.78 g·m^(-2)·yr^(−1),while the threshold value of degraded grassland(3.65 g·m^(-2)·yr^(−1))is lower than that of nondegraded grassland(5.90 g·m^(-2)·yr^(−1)).The low nitrogen-driven thresholds are affected by degradation status,climate(precipitation and temperature),and other site conditions,but not fertilization forms.Independent experiments further demonstrated that an increase in soil moisture content can lead to the disappearance of nitrogen threshold effects,revealing that ecological threshold effects are influenced by ecosystem stress factors.Following the significant increase in plant biomass triggered by the nitrogen threshold,the ecosystem undergoes systemic improvement.Soil organic carbon,urease activity,soil microbial diversity,and other soil properties are significantly enhanced.Soil nitrogen cycle-related microbial communities and soil physicochemical attributes are significantly activated.The results indicate that a threshold response pattern may develop before nitrogen saturation is reached,and low nitrogen input can boost productivity and improve the plant-soil-microbe system.Our findings reveal a nonprogressive path of restoration in degraded ecosystems,and thus,restoration based on threshold effects can offer an efficient and safe solution to combat ecological degradation.
基金funded by the National Natural Science Foundation of China(Nos.82103686 and 22101267)the China Postdoctoral Science Foundation(No.2021M692905 and 2024T170832)Natural Science Foundation of Henan Province(242300421123).
文摘Nitrogen-containing structures represent a significant branch exhibiting remarkable biological activity,surpassing non-nitrogen architectures.Given the vast array of nitrogen-containing compounds and their crucial role in the pharmaceutical industry,chemists have been motivated to devise efficient,cost-effective,and practical methods for C-N bond formation.Significant advancements have been achieved in this cutting-edge field over the past few decades.This review aims to encapsulate the latest progress in C-N bond formation via the photocatalytic C-H amination process.Initially,we provide a comprehensive introduction to C-H amination transformations.Subsequently,we categorize these photochemical conversions into two parts:intramolecular and intermolecular C-H amination.To elucidate the underlying principles of specific illustrative examples,we have carefully chosen and elaborated on the reaction mechanisms,representative experimental outcomes,and applications.
基金Supported by the National Natural Science Foundation of China(Nos.42141003,42176147)the National Key Research and Development Program of China(No.2022YFF0802204)the Xiamen Key Laboratory of Urban Sea Ecological Conservation and Restoration(USER)(Nos.USER2021-1,USER2021-5)。
文摘Ecological floating bed is an important biological remediation method for water pollution control.During the removal of excess nutrients and pollutants,changes in environmental factors affect the characteristics of microorganisms in aquatic ecosystems.To understand the influences of ecological floating beds on size-fractionated microorganisms,we investigated the community assembly and nitrogen metabolic characteristics of three size-fractionated microorganism groups in the ecological floating bed area,using 18S rDNA,16S rDNA metabarcoding,and metagenomic sequencing techniques.Firstly,we discovered substantial differences between size-fractionated groups in the diversity and compositions of both microeukaryotic and bacterial communities,as well as the influences of floating beds on specific groups.The floating beds appeared to provide more habitats for heterotrophs and symbiotes while potentially inhibiting the growth of certain phytoplankton(cyanobacteria).Secondly,we observed that microeukaryotic and bacterial communities were predominantly influenced by stochastic and deterministic processes,respectively,and they both exhibited distinct patterns across different size-fractionated groups.Notably,microeukaryotic community assembly demonstrated a greater sensitivity to ecological floating beds,as indicated by an increase in dispersal limitation processes.Finally,the nitrogen metabolism functional genes revealed that microbes associated with large-sized particles played a crucial role in dissimilatory nitrate reduction to ammonium(DNRA)and denitrification processes within the floating bed area,thereby facilitating the removal of excess nitrogen nutrients from the water.In contrast,freeliving microorganisms from small-sized groups were linked mainly to the genes involved in nitrogen assimilation and assimilatory nitrate reduction to ammonium(ANRA)processes.These findings help understand the impact of ecological floating beds on the diversity and functional characteristics of microorganism communities in different size-fractionated groups.
基金supported by the Anhui Provincial Natural Science Foundation (Grant No.2508085J006)CASHIPS Director's Fund (Grant No.YZJJ202207-CX)。
文摘The zigzag nitrogen chain,similar to the Ch-N structure,has long been considered as a potential high-energy-density structure.However,all the previously predicted zigzag N-chain structures,similar to Ch-N,exhibited imaginary frequencies in their phonon spectra at 0 GPa.Here,we conducted a systematic investigation of P-N compounds using first-principles calculations,uncovering a series of structurally similar stable phases,C2/m-PN_(x)(x=6,8,10,12,and 14),in which N forms zigzag N chains similar to those in Ch-N.In P-N compounds,the longest zigzag N-chain,which can theoretically remain stable under ambient pressure,is the N-chain composed of 14 N atoms in C2/m-PN14.If the N-chain continues to grow,imaginary interchain vibrational frequencies arise in the system.Notably,N chains with an even number of atoms were more likely to be energetically favorable.The five C2/m-PN_(x) phases and one metastable phase(R-PN_(6))exhibited remarkable stability and excellent detonability at ambient pressure,indicating that they are promising candidates for high-energy-density materials.In addition,R-PN_(6) was the first structure to stabilize the N_(6) ring through covalent bonding,with the covalent network contributing to its high hardness(47.59 GPa).
基金financial supports from the National Science and Technology Major Project of China(No.2025ZD0611202)National Key R&D Program of China(No.2021YFB3702403)+1 种基金the National Natural Science Foundation of China(Nos.52371017,52293395,and 52401137)Open Fund Project of State Key Laboratory of Materials Processing and Die and Mould Technology(P2024-005).
文摘A systematic investigation was conducted on the influence of residual nitrogen(0.003–0.008 wt.%)on the microstructure,mechanical properties,and strain aging behavior of scrap-electric arc furnace produced SAPH440 low-alloy steel.Through internal friction spectroscopy,transmission electron microscopy,and atom probe tomography,the occurrence state of nitrogen and its interaction with dislocations under simulated industrial pre-strain(2%,10%)and aging conditions(250°C/h)were elucidated.Increasing nitrogen content was found to refine ferrite grain size and enhance strength,but it also drastically reduced ductility and impact toughness due to heightened strain aging sensitivity.Nitrogen levels≥0.008 wt.%promoted extensive Cottrell atmosphere formation,which pinned dislocations and caused severe embrittlement after aging,leading to additional yield strength increments of up to 147 MPa(2%strain)and 164 MPa(10%strain),while elongation fell below 16%and 8.3%,respectively.Critically,even 2%pre-strain immobilized virtually all nitrogen atoms≤0.008 wt.%,precipitating significant property degradation.Nitrogen segregation at grain boundaries and dislocation networks after strain aging was directly observed.
基金Supported by Science and Technology Project of China Tobacco Zhejiang Industrial Co.,Ltd.(2023330000340093).
文摘[Objectives]To investigate the effects of different planting densities and nitrogen application rates on the yield and quality of the tobacco cultivar Chuxue 80.[Methods]A field experiment was conducted in Hubei Province,evaluating various combinations of planting density and nitrogen rate for Chuxue 80.[Results]At the maturity stage,the TN1 treatment(5 kg N per 667 m^(2) with a density of 1900 plants per 667 m^(2))demonstrated the most favorable agronomic performance.The TN9 treatment(11 kg N per 667 m^(2) with a density of 1110 plants per 667 m^(2))achieved the highest wrapper tobacco yield and output value.Meanwhile,the TN5 treatment(8 kg N per 667 m^(2) with a density of 1515 plants per 667 m^(2))resulted in the best smoking quality.[Conclusions]The TN9 treatment,with a planting density of 1110 plants per 667 m^(2) and a nitrogen application rate of 11 kg per 667 m^(2),is recommended as the optimal cultivation practice for Chuxue 80 in Hubei Province.
基金supported by the Scientific Research Foundation supported by Yunnan Agricultural University(A3012024035044)International Cooperation and Exchange of the National Natural Science Foundation of China(No.42361144885).
文摘The establishment of plantations has become a critical approach for reducing greenhouse gas emissions,particularly in fragile environments with carbon sequestration potential.In karst areas,plantations based on fastgrowing afforestation species made significant contributions to enhancing carbon sequestration.However,the impact of understory vegetation on carbon accumulation remains unclear.Especially,the carbon accumulation associated with litter produced during the replacement of understory species receives insufficient attention,which leads to the neglect of the carbon sequestration potential in plantations of karst areas.Leaf is a crucial organ that links the litter production.To explore how leaf traits adapt to competitive environments and drive litter carbon accumulation during understory species replacement,this study observed leaf traits and litter carbon content changes in three types of plantations in the Liujiang River Basin,a typical karst area.A total of 37 sampling plots were selected for field investigation over a twoyear period.Leaf traits,species diversity,vegetation coverage,and litter carbon characteristics in understory vegetation were measured.Variance analysis,allometric equations,and path analysis were used for data analysis.The results showed that most understory species adopted a biomass conservation strategy under high-coverage conditions(>44.27%)and expanded competitive leaf area under low-coverage conditions(<44.27%).However,Bidens pilosa and Miscanthus floridulus exhibited strong competitiveness during understory species replacement.They showed an expansion of competitive leaf area under high-coverage conditions.This competitive strategy reduced species diversity and community specific leaf area.But the rapid expansion of Bidens pilosa and Miscanthus floridulus increased understory vegetation coverage,and their increased specific leaf area facilitated leaf shedding,resulting in significant litter weight accumulation(P<0.05),thereby enhancing litter carbon content per unit area.These competitive strategies were key driving factors for the increase in litter carbon content per square meter,which reached a maximum of 49.6% higher than that in natural grasslands.And the maximum increase in litter carbon accumulation derived from understory vegetation reached 3.37 times from 2023 to 2024 in plantations.In the understory vegetation of plantations,the competitive strategies reflected by leaf adaptation of key competitive species are critical factors influencing litter carbon accumulation.Future research could deeply explore the carbon sequestration effects resulting from the dynamic changes in competition within the understory vegetation of plantations.
基金supported by the Science and Technology Project of Hebei Education Department(No.QN2023028)the Natural Science Foundation of Hebei Province(No.C2022201042)+1 种基金the High-level Talent Research Funding Project of Hebei University(Nos.521000981405 and 521000981186)the Collaborative Innovation Center for Baiyangdian Basin Ecological Protection and Beijing-Tianjin-Hebei Sustainable Development.
文摘Climate warming and atmospheric nitrogen(N)deposition have profound influences on the terrestrial biosphere.However,how these two global change drivers affect phytoplankton which are important primary producers in wetlands with large carbon stocks and complex hydrological fluctuations remain largely unclear.As part of a two-year field experiment in a freshwater wetland,this study was conducted to investigate the effects of nighttime warming and N addition on phytoplankton biomass in the North China Plain.The results showed that neither nighttime warming nor N addition influenced the Shannon-Wiener index of phytoplankton community.Nighttime warming did not change phytoplankton biomass,likely due to the different warming impacts on dominant phyla and in different seasons.Decreased phytoplankton biomass in spring because of the increased water pH and submerged plant coverage was compensated by the enhanced biomass in autumn due to the reduced dissolved oxygen and submerged plant coverage,leading to the neutral change of phytoplankton biomass under warming.Nitrogen addition elevated phytoplankton biomass by 11.6%,which could be attributed to the enhanced nutrient availability and reduced submerged plant coverage.Positive relationships of methane(CH4)emission rates at the water-air interface with phytoplankton biomass indicated the potentially crucial role of phytoplankton in mediating wetland CH4 cycling through photosynthesis-driven metabolisms.The findings suggested the seasonal variation of phytoplankton and their potential responses to nighttime warming and N deposition,which may provide a more accurate basis for assessing the global change-carbon feedback in wetland ecosystems.
基金supported by the National Natural Science Foundation of China(Nos.32371680 and 41807321)Chongqing Natural Science Foundation of China(Nos.CSTB2023NSCQ-LZX0150 and 2022NSCQMSX2598)the Science and Technology Research Program of Chongqing Education Commission of China(Nos.KJQN202200536 and KJQN202203222).
文摘Reservoir is an important source of CO_(2) emissions.The backwater bay is a distinct hydrological unit formed in the open channel of canyon-reservoir as a result of impoundment.It is characterized by efficient nutrients retention and a propensity for frequent eutrophication.However,the spatio-temporal dynamics of CO_(2) emissions in these backwater bays remain unclear.This study investigated CO_(2) fluxes(fCO_(2))in two different backwater bays(Hanfeng Lake and Gaoyang Lake)within the Three Gorges Reservoir(TGR),to reveal the spatio-temporal dynamics and driving factors of CO_(2) emissions.The two backwater bays serve as minor sources of CO_(2) emissions,exhibiting lower fCO_(2) compared to other water areas within the TGR.In the subsiding and low water level periods of the TGR,the fCO_(2) in the two backwater bays were significantly lower,with some areas even converting into CO_(2) sinks due to extensive eutrophication.However,the water flow backward caused by the TGR water level elevation simultaneously enhances CO_(2) emissions by diluting algae density and constraining primary production.We highlighted that nutrients enrichment,eutrophication,and water level fluctuations co-dominate the temporal dynamics of CO_(2) emissions from backwater bays in the TGR.The CO_(2) fluxes decreased from upstream to downstream in the two backwater bays.The spatial distribution of nutrients and related algal density are critical factors driving this pattern.The key factors influencing CO_(2) emissions in the backwater bays diversified with water level fluctuations.Our findings contribute to a better understanding of CO_(2) emissions in large reservoirs with varying hydrological habitats.
基金financially supported by the National Natural Science Foundation of China(32301962 and 31901127)the China Postdoctoral Science Foundation(2024M752947)+2 种基金the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(GZC20232437)the State Key Laboratory of Cotton Bio-breeding and Integrated Utilization Open Fund,China(CB2023C02)the Natural Science Foundation of Henan Province,China(252300420222)。
文摘Legume-based intercropping enhances asymbiotic biological nitrogen fixation(BNF);however,the underlying mechanisms remain unclear,including the roles of soil keystone diazotroph taxa with varying niche breadths.A field experiment was conducted to evaluate soil BNF variations between rhizosphere and bulk soils in peanut/cotton intercropping systems and monocultures.BNF activities were measured by nitrogen fixation rates,nitrogenase activity,and nifH gene abundance.Phylogenetic null models,co-occurrence networks,and niche breadth analysis were applied to investigate the roles of diazotrophic keystone taxa and their ecological niches.Rhizosphere soils exhibited 7.8–125.5%higher BNF potentials than bulk soils,whereas intercropping systems showed 11.6–323.0%increases over monocultures for nitrogen fixation rate,nitrogenase activity,and nifH gene abundance(all P<0.05).Diazotrophic community composition and diversity differed significantly,with Proteobacteria(excluding Alphaproteobacteria)enriched in intercropping and rhizosphere soils,while Cyanobacteria and Firmicutes were less abundant.Deterministic processes,particularly heterogeneous selection,dominated community assembly in the rhizosphere(91.9%)and intercropping soils(86.3%).The co-occurrence networks consistently revealed more complex and interconnected communities in intercropping and rhizosphere soils that were dominated by opportunistic diazotrophs(78.8–85.9%),followed by specialists(10.2–18.5%)and generalists(1.38–3.80%).Keystone taxa,including opportunists such as Azoarcus,Azohydromonas,and Steroidobacter,and generalists like Pseudomonas and Azotobacter,correlated positively with microbial biomass carbon and nitrate nitrogen,contributing to enhanced BNF.Peanut/cotton intercropping enhances BNF by selectively enriching the keystone diazotrophic taxa with varying ecological roles,particularly opportunists and generalists.Such targeted intercropping strategies can optimize BNF,improve soil fertility,and promote sustainable agricultural production.
基金supported by the National Natural Science Foundation of China(Grant No.22479046,22461142135)。
文摘Cellulose,the most abundant and renewable biopolymer,offers a sustainable and cost-effective solution for regulating lithium electrodeposition toward safer lithium metal batteries,thanks to its high nanofibrous structure and intrinsic lithiophilic property.In this work,we introduce interface-engineered cellulose-based separators by converting intrinsic hydroxyl groups on cellulose nanofibers(CNFs)to nitrogen functionalities through a trace conducting polymer coating.Both experimental and theoretical results reveal that the nitrogen moieties disrupt the compact hydrogen bond network within hydroxyl cellulose,enabling multiple nitrogen-lithium interactions that enhance lithium ion transport.In addition to an extraordinary Li^(+)transference number of 0.86 and a high ionic conductivity of 1.1 mS cm^(-1),the nitrogen-functionalized CNF contributes to a uniform electric field and Li^(+)concentration distribution across the lithium metal surface.This facilitates the formation of a LiF-rich solid electrolyte interface and suppresses Li dendrite growth.Consequently,Li‖Li cells demonstrate stable plating/stripping cycles for approximately 3000 h at a current density of 1 mA cm^(-2) with a fixed capacity of 1 mAh cm^(-2),while maintaining a low overpotential of 15 mV.Our work provides valuable insights into the surface functionalization of natural biomass for advancing sustainable energy storage technologies.
基金financially supported by the National Key R&D Program of China(2024YFD1200800)the Guangdong Basic and Applied Basic Research Foundation,China(2024A1515030094)。
文摘Highlights OsCAX2 is localized to tonoplast,and cadmium induces its expression.OsCAX2 overexpression reduces cadmium concentration in indica rice grains by 49.1%.Cadmium(Cd)exposure poses significant health risks to humans,and the International Agency for Research on Cancer has classified it as a Group I carcinogen.Cadmium undergoes minimal metabolism in the human body;consequently,prolonged Cd^(2+)exposure can cause severe damage to multiple organs including the liver,kidneys,lungs,bones,and immune system(Shao et al.2024).Rice,one of the three global staple crops,and Cd exposure in humans primarily occurs the consumption of contaminated rice grains.The contribution of rice to the total dietary Cd intake is over 50% for non-smoking Asian populations(Chen et al.2018;Shi et al.2020).
