OsNPF3.1,a nitrate,abscisic acid and gibberellin transporter gene,is essential for rice tillering and nitrogen utilization efficiency

Low-affinity nitrate transporter genes have been identified in subfamilies 4-8 of the rice nitrate transporter 1(NRT1)/peptide transporter family(NPF),but the OsNPF3 subfamily responsible for nitrate and phytohormone transport and rice growth and development remains unknown.In this study,we described OsNPF3.1 as an essential nitrate and phytohormone transporter gene for rice tillering and nitrogen utilization efficiency(NUtE).OsNPF3.1 possesses four major haplotypes of its promoter sequence in 517 cultivars,and its expression is positively associated with tiller number.Its expression was higher in the basal part,culm,and leaf blade than in other parts of the plant,and was strongly induced by nitrate,abscisic acid(ABA)and gibberellin 3(GA_3)in the root and shoot of rice.Electrophysiological experiments demonstrated that OsNPF3.1 is a pH-dependent low-affinity nitrate transporter,with rice protoplast uptake assays showing it to be an ABA and GA_3 transporter.OsNPF3.1 overexpression significantly promoted ABA accumulation in the roots and GA accumulation in the basal part of the plant which inhibited axillary bud outgrowth and rice tillering,especially at high nitrate concentrations.The NUtE of OsNPF3.1-overexpressing plants was enhanced under low and medium nitrate concentrations,whereas the NUtE of OsNPF3.1 clustered regularly interspaced short palindromic repeats(CRISPR)plants was increased under high nitrate concentrations.The results indicate that OsNPF3.1 transports nitrate and phytohormones in different rice tissues under different nitrate concentrations.The altered OsNPF3.1 expression improves NUtE in the OsNPF3.1-overexpressing and CRISPR lines at low and high nitrate concentrations,respectively.

Integrated assessment of yield,nitrogen use efficiency and ecosystem economic benefits of use of controlled-release and common urea in ratoon rice production

Controlled-release urea(CRU)is commonly used to improve the crop yield and nitrogen use efficiency(NUE).However,few studies have investigated the effects of CRU in the ratoon rice system.Ratoon rice is the practice of obtaining a second harvest from tillers originating from the stubble of the previously harvested main crop.In this study,a 2-year field experiment using a randomized complete block design was conducted to determine the effects of CRU on the yield,NUE,and economic benefits of ratoon rice,including the main crop,to provide a theoretical basis for fertilization of ratoon rice.The experiment included four treatments:(i)no N fertilizer(CK);(ii)traditional practice with 5 applications of urea applied at different crop growth stages by surface broadcasting(FFP);(iii)one-time basal application of CRU(BF1);and(iv)one-time basal application of CRU combined with common urea(BF2).The BF1 and BF2 treatments significantly increased the main crop yield by 17.47 and 15.99%in 2019,and by 17.91 and 16.44%in 2020,respectively,compared with FFP treatment.The BF2 treatment achieved similar yield of the ratoon crop to the FFP treatment,whereas the BF1 treatment significantly increased the yield of the ratoon crop by 14.81%in 2019 and 12.21%in 2020 compared with the FFP treatment.The BF1 and BF2 treatments significantly improved the 2-year apparent N recovery efficiency,agronomic NUE,and partial factor productivity of applied N by 11.47-16.66,27.31-44.49,and 9.23-15.60%,respectively,compared with FFP treatment.The BF1 and BF2 treatments reduced the chalky rice rate and chalkiness of main and ratoon crops relative to the FFP treatment.Furthermore,emergy analysis showed that the production efficiency of the BF treatments was higher than that of the FFP treatment.The BF treatments reduced labor input due to reduced fertilization times and improved the economic benefits of ratoon rice.Compared with the FFP treatment,the BF1 and BF2 treatments increased the net income by 14.21-16.87 and 23.76-25.96%,respectively.Overall,the one-time blending use of CRU and common urea should be encouraged to achieve high yield,high nitrogen use efficiency,and good quality of ratoon rice,which has low labor input and low apparent N loss.

Regulation effects of water and nitrogen on yield,water,and nitrogen use efficiency of wolfberry

Wolfberry(Lycium barbarum L.)is important for health care and ecological protection.However,it faces problems of low productivity and resource utilization during planting.Exploring reasonable models for water and nitrogen management is important for solving these problems.Based on field trials in 2021 and 2022,this study analyzed the effects of controlling soil water and nitrogen application levels on wolfberry height,stem diameter,crown width,yield,and water(WUE)and nitrogen use efficiency(NUE).The upper and lower limits of soil water were controlled by the percentage of soil water content to field water capacity(θ_(f)),and four water levels,i.e.,adequate irrigation(W0,75%-85%θ_(f)),mild water deficit(W1,65%-75%θ_(f)),moderate water deficit(W2,55%-65%θ_(f)),and severe water deficit(W3,45%-55%θ_(f))were used,and three nitrogen application levels,i.e.,no nitrogen(N0,0 kg/hm^(2)),low nitrogen(N1,150 kg/hm^(2)),medium nitrogen(N2,300 kg/hm^(2)),and high nitrogen(N3,450 kg/hm^(2))were implied.The results showed that irrigation and nitrogen application significantly affected plant height,stem diameter,and crown width of wolfberry at different growth stages(P<0.01),and their maximum values were observed in W1N2,W0N2,and W1N3 treatments.Dry weight per plant and yield of wolfberry first increased and then decreased with increasing nitrogen application under the same water treatment.Dry weight per hundred grains and dry weight percentage increased with increasing nitrogen application under W0 treatment.However,under other water treatments,the values first increased and then decreased with increasing nitrogen application.Yield and its component of wolfberry first increased and then decreased as water deficit increased under the same nitrogen treatment.Irrigation water use efficiency(IWUE,8.46 kg/(hm^(2)·mm)),WUE(6.83 kg/(hm^(2)·mm)),partial factor productivity of nitrogen(PFPN,2.56 kg/kg),and NUE(14.29 kg/kg)reached their highest values in W2N2,W1N2,W1N2,and W1N1 treatments.Results of principal component analysis(PCA)showed that yield,WUE,and NUE were better in W1N2 treatment,making it a suitable water and nitrogen management mode for the irrigation area of the Yellow River in the Gansu Province,China and similar planting areas.

Plasma nitrogen fixation system with dual-loop enhancement for improved energy efficiency and its efficacy for lettuce cultivation

Plasma nitrogen fixation(PNF)has been emerging as a promising technology for greenhouse gasfree and renewable energy-based agriculture.Yet,most PNF studies seldom address practical application-specific issues.In this work,we present the development of a compact and automatic PNF system for on-site agricultural applications.The system utilized a gliding-arc discharge as the plasma source and employed a dual-loop design to generate NO_(x)from air and water under atmospheric conditions.Experimental results showed that the system with a dualloop design performs well in terms of energy costs and production rates.Optimal operational parameters for the system were determined through experimentation,resulting in an energy cost of 13.9 MJ mol^(-1)and an energy efficiency of 16 g kWh^(-1)for NO_(3)^(-)production,respectively.Moreover,the concentration of exhausted NO_(x)was below the emission standards.Soilless lettuce cultivation experiments demonstrated that NO_(x)^(-)produced by the PNF system could serve as liquid nitrate nitrogen fertilizer.Overall,our work demonstrates the potential of the developed PNF system for on-site application in the production of green-leaf vegetables.

Optimization of inter-seasonal nitrogen allocation increases yield and resource-use efficiency in a water-limited wheat-maize cropping system in the North China Plain

Winter wheat–summer maize cropping system in the North China Plain often experiences droughtinduced yield reduction in the wheat season and rainwater and nitrogen(N)fertilizer losses in the maize season.This study aimed to identify an optimal interseasonal water-and N-management strategy to alleviate these losses.Four ratios of allocation of 360 kg N ha^(-1)between the wheat and maize seasons under one-time presowing root-zone irrigation(W0)and additional jointing and anthesis irrigation(W2)in wheat and one irrigation after maize sowing were set as follows:N1(120:240),N2(180:180),N3(240:120)and N4(300:60).The results showed that under W0,the N3 treatment produced the highest annual yield,crop water productivity(WPC),and nitrogen partial factor productivity(PFPN).Increased N allocation in wheat under W0 improved wheat yield without affecting maize yield,as surplus nitrate after wheat harvest was retained in the topsoil layers and available for the subsequent maize.Under W2,annual yield was largest in the N2 treatment.The risk of nitrate leaching increased in W2 when N application rate in wheat exceeded that of the N2 treatment,especially in the wet year.Compared to W2N2,the W0N3 maintained 95.2%grain yield over two years.The WPCwas higher in the W0 treatment than in the W2 treatment.Therefore,following limited total N rate,an appropriate fertilizer N transfer from maize to wheat season had the potential of a“triple win”for high annual yield,WPCand PFPN in a water-limited wheat–maize cropping system.

Genome-wide association study of seedling nitrogen-use efficiency-associated traits in common wheat(Triticum aestivum L.)

Nitrogen(N)fertilizer application is essential for crop-plant growth and development.Identifying genetic loci associated with N-use efficiency(NUE)could increase wheat yields and reduce environmental pollution caused by overfertilization.We subjected a panel of 389 wheat accessions to N and chlorate(a nitrate analog)treatments to identify quantitative trait loci(QTL)controlling NUE-associated traits at the wheat seedling stage.Genotyping the panel with a 660K single-nucleotide polymorphism(SNP)array,we identified 397 SNPs associated with N-sensitivity index and chlorate inhibition rate.These SNPs were merged into 49 QTL,of which eight were multi-environment stable QTL and 27 were located near previously reported QTL.A set of 135 candidate genes near the 49 QTL included TaBOX(F-box family protein)and TaERF(ethylene-responsive transcription factor).A Tabox mutant was more sensitive to low-N stress than the wild-type plant.We developed two functional markers for Hap 1,the favorable allele of TaBOX.

Carbon sequestration rate,nitrogen use efficiency and rice yield responses to long-term substitution of chemical fertilizer by organic manure in a rice–rice cropping system

Combined application of chemical fertilizers with organic amendments was recommended as a strategy for improving yield,soil carbon storage,and nutrient use efficiency.However,how the long-term substitution of chemical fertilizer with organic manure affects rice yield,carbon sequestration rate(CSR),and nitrogen use efficiency(NUE)while ensuring environmental safety remains unclear.This study assessed the long-term effect of substituting chemical fertilizer with organic manure on rice yield,CSR,and NUE.It also determined the optimum substitution ratio in the acidic soil of southern China.The treatments were:(i)NPK0,unfertilized control;(ii)NPK1,100%chemical nitrogen,phosphorus,and potassium fertilizer;(iii)NPKM1,70%chemical NPK fertilizer and 30%organic manure;(iv)NPKM2,50%chemical NPK fertilizer and 50%organic manure;and(v)NPKM3,30%chemical NPK fertilizer and 70%organic manure.Milk vetch and pig manure were sources of manure for early and late rice seasons,respectively.The result showed that SOC content was higher in NPKM1,NPKM2,and NPKM3 treatments than in NPK0 and NPK1 treatments.The carbon sequestration rate increased by 140,160,and 280%under NPKM1,NPKM2,and NPKM3 treatments,respectively,compared to NPK1 treatment.Grain yield was 86.1,93.1,93.6,and 96.5%higher under NPK1,NPKM1,NPKM2,and NPKM3 treatments,respectively,compared to NPK0 treatment.The NUE in NPKM1,NPKM2,and NPKM3 treatments was higher as compared to NPK1 treatment for both rice seasons.Redundancy analysis revealed close positive relationships of CSR with C input,total N,soil C:N ratio,catalase,and humic acids,whereas NUE was closely related to grain yield,grain N content,and phenol oxidase.Furthermore,CSR and NUE negatively correlated with humin acid and soil C:P and N:P ratios.The technique for order of preference by similarity to ideal solution(TOPSIS)showed that NPKM3 treatment was the optimum strategy for improving CSR and NUE.Therefore,substituting 70%of chemical fertilizer with organic manure could be the best management option for increasing CSR and NUE in the paddy fields of southern China.

Grain yield and nitrogen use efficiency of an ultrashort-duration variety grown under different nitrogen and seeding rates in direct-seeded and double-season rice in Central China

Nitrogen(N) and seeding rates are important factors affecting grain yield and N use efficiency(NUE) in directseeded rice. However, these factors have not been adequately investigated on direct-seeded and double-season rice(DDR) in Central China. The objective of this study was to evaluate the effects of various N and seeding rates on the grain yield and NUE of an ultrashort-duration variety grown under DDR. Field experiments were conducted in 2018 in Wuxue County and 2019 in Qichun County, Hubei Province, China with four N rates and three seeding rates.The results showed that the grain yield of the ultrashort-duration variety ranged from 6.32 to 8.23 t ha–1with a total growth duration of 85 to 97 days across all treatments with N application. Grain yield was increased significantly by N application in most cases, but seeding rate had an inconsistent effect on grain yield. Furthermore, the response of grain yield to the N rates was much higher than the response to seeding rates. The moderate N rates of 100–150 and 70–120 kg N ha–1in the early and late seasons, respectively, could fully express the yield potential of the ultrashort-duration variety grown under DDR. Remarkably higher N responses and agronomic NUE levels were achieved in the early-season rice compared with the late-season rice due to the difference in indigenous soil N supply capacity(INS) between the two seasons. Seasonal differences in INS and N response should be considered when crop management practices are optimized for achieving high grain yield and NUE in ultrashort-duration variety grown under DDR.

Grain yield,nitrogen use efficiency and physiological performance of indica/japonica hybrid rice in response to various nitrogen rates

Utilizing the heterosis of indica/japonica hybrid rice(IJHR)is an effective way to further increase rice grain yield.Rational application of nitrogen(N)fertilizer plays a very important role in using the heterosis of IJHR to achieve its great yield potential.However,the responses of the grain yield and N utilization of IJHR to N application rates and the underlying physiological mechanism remain elusive.The purpose of this study was to clarify these issues.Three rice cultivars currently used in rice production,an IJHR cultivar Yongyou 2640(YY2640),a japonica cultivar Lianjing 7(LJ-7)and an indica cultivar Yangdao 6(YD-6),were grown in the field with six N rates(0,100,200,300,400,and 500 kg ha^(-1))in 2018 and 2019.The results showed that with the increase in N application rates,the grain yield of each test cultivar increased at first and then decreased,and the highest grain yield was at the N rate of 400 kg ha^(-1)for YY2640,with a grain yield of 13.4 t ha^(-1),and at 300 kg ha^(-1)for LJ-7 and YD-6,with grain yields of 9.4–10.6 t ha^(-1).The grain yield and N use efficiency(NUE)of YY2640 were higher than those of LJ-7 or YD-6 at the same N rate,especially at the higher N rates.When compared with LJ-7 or YD-6,YY2640 exhibited better physiological traits,including greater root oxidation activity and leaf photosynthetic rate,higher cytokinin content in the roots and leaves,and more remobilization of assimilates from the stem to the grain during grain filling.The results suggest that IJHR could attain both higher grain yield and higher NUE than inbred rice at either low or high N application rates.Improved shoot and root traits of the IJHR contribute to its higher grain yield and NUE,and a higher content of cytokinins in the IJHR plants plays a vital role in their responses to N application rates and also benefits other physiological processes.

Co-overexpression of genes for nitrogen transport, assimilation, and utilization boosts rice grain yield and nitrogen use efficiency

Nitrogen(N)fertilization is necessary for obtaining high rice yield.But excessive N fertilizer reduces rice plant N efficiency and causes negative effects such as environmental pollution.In this study,we assembled key genes involved in different nodes of N pathways to boost nitrate and ammonium uptake and assimilation,and to strengthen amino acid utilization to increase grain yield and nitrogen use efficiency(NUE)in rice.The combinations OsNPF8.9a×OsNR2,OsAMT1;2×OsGS1;2×OsAS1,and OsGS2×OsAS2×OsANT3 optimized nitrate assimilation,ammonium conversion,and N reutilization,respectively.In co-overexpressing rice lines obtained by co-transformation,the tiller number,biomass,and grain yield per plant of the OsAMT1;2×OsGS1;2×OsAS1-overexpressing line exceeded those of wild-type ZH11,the OsNPF8.9a×OsNR2×OsGS1;2×OsAS1-overexpressing line,and the OsGS2×OsAS2×OsANT3-overexpressing line.The glutamine synthase activity,free amino acids,and nitrogen utilization efficiency(NUt E)of the OsAMT1;2×OsGS1;2×OsAS1-overexpressing line exceeded those of ZH11 and other lines that combined key genes.N influx efficiency was increased in the OsAMT1;2×OsGS1;2×OsAS1-overexpressing line and OsNPF8.9a×OsNR2×OsGS1;2×OsAS1-overexpressing line under a low ammonium and a low nitrate treatment,respectively.We propose that combining overexpression of OsAMT1;2,OsGS1;2,and OsAS1 is a promising breeding strategy for systematically increasing rice grain yield and NUE by focusing on key nodes in the N pathway.

Tiller fertility is critical for improving grain yield,photosynthesis,and nitrogen efficiency in wheat

Genetic improvement has promoted wheat’s grain yield and nitrogen use efficiency(NUE)during the past decades.Therefore,the current wheat cultivars exhibit higher grain yield and NUE than previous cultivars in the Yangtze River Basin,China since the 2000s.However,the critical traits and mechanisms of the increased grain yield and NUE remain unknown.This study explores the mechanisms underlying these new cultivars’increased grain yield and NUE by studying 21 local cultivars cultivated for three growing seasons from 2016 to 2019.Significantly positive correlations were observed between grain yield and NUE in the three years.The cultivars were grouped into high(HH),medium(MM),and low(LL)grain yield and NUE groups.The HH group exhibited significantly high grain yield and NUE.High grain yield was attributed to more effective ears by high tiller fertility and greater single-spike yield by increasing post-anthesis single-stem biomass.Compared to other groups,the HH group demonstrated a longer leaf stay-green ability and a greater flag leaf photosynthetic rate after anthesis.It also showed higher N accumulation at pre-anthesis,which contributed to increasing N accumulation per stem,including stem and leaf sheath,leaf blade,and unit leaf area at pre-anthesis,and promoting N uptake efficiency,the main contribution of high NUE.Moreover,tiller fertility was positively related to N accumulation per stem,N accumulation per unit leaf area,leaf stay-green ability,and flag leaf photosynthetic rate,which indicates that improving tiller fertility promoted N uptake,leaf N accumulation,and photosynthetic ability,thereby achieving synchronous improvements in grain yield and NUE.Therefore,tiller fertility is proposed as an important kernel indicator that can be used in the breeding and management of cultivars to improve agricultural efficiency and sustainability.

Predicting nitrogen use efficiency,nitrogen loss and dry matter intake of individual dairy cows in late lactation by including mid‑infrared spectra of milk samples

Background Nitrate leaching to groundwater and surface water and ammonia volatilization from dairy farms have negative impacts on the environment.Meanwhile,the increasing demand for dairy products will result in more pollution if N losses are not controlled.Therefore,a more efficient,and environmentally friendly production system is needed,in which nitrogen use efficiency(NUE)of dairy cows plays a key role.To genetically improve NUE,extensively recorded and cost-effective proxies are essential,which can be obtained by including mid-infrared(MIR)spectra of milk in prediction models for NUE.This study aimed to develop and validate the best prediction model of NUE,nitrogen loss(NL)and dry matter intake(DMI)for individual dairy cows in China.Results A total of 86 lactating Chinese Holstein cows were used in this study.After data editing,704 records were obtained for calibration and validation.Six prediction models with three different machine learning algorithms and three kinds of pre-processed MIR spectra were developed for each trait.Results showed that the coefficient of determination(R2)of the best model in within-herd validation was 0.66 for NUE,0.58 for NL and 0.63 for DMI.For external validation,reasonable prediction results were only observed for NUE,with R2 ranging from 0.58 to 0.63,while the R2 of the other two traits was below 0.50.The infrared waves from 973.54 to 988.46 cm−1 and daily milk yield were the most important variables for prediction.Conclusion The results showed that individual NUE can be predicted with a moderate accuracy in both within-herd and external validations.The model of NUE could be used for the datasets that are similar to the calibration dataset.The prediction models for NL and 3-day moving average of DMI(DMI_a)generated lower accuracies in within-herd validation.Results also indicated that information of MIR spectra variables increased the predictive ability of models.Additionally,pre-processed MIR spectra do not result in higher accuracy than original MIR spectra in the external validation.These models will be applied to large-scale data to further investigate the genetic architecture of N efficiency and further reduce the adverse impacts on the environment after more data is collected.

OsAMT1.1 Expression by Nitrate-Inducible Promoter of OsNAR2.1 Increases Nitrogen Use Efficiency and Rice Yield

Nitrate(NO_(3)^(-))and ammonium(NH_(4)^(+))are two main inorganic nitrogen(N)sources during crop growth.Here,we enhanced the expression of OsAMT1.1,which encodes a NH_(4)^(+)transporter,using the NO_(3)^(-)-inducible promoter of OsNAR2.1 and an ubiquitin promoter in transgenic rice plants.Under field condition of 120 kg/hm2 N,agronomic N use efficiency,N recovery efficiency and N transport efficiency,and grain yield of the pOsNAR2.1:OsAMT1.1 transgenic lines were increased compared with those of the wild type(WT)and the pUbi:OsAMT1.1 transgenic plants.Under 2.0 mmol/L NO_(3)^(-)+0.5 mmol/L NH_(4)^(+)and 0.5 mmol/L NO_(3)^(-)+2.0 mmol/L NH_(4)^(+)conditions of hydroponic culture,compared with the WT,both biomass and total N content were increased in the pOsNAR2.1:OsAMT1.1 transgenic lines.However,biomass was significantly reduced in pUbi:OsAMT1.1 transgenic plants under 0.5 mmol/L NO_(3)^(-)+2.0 mmol/L NH_(4)^(+)condition.The lines expressing pOsNAR2.1:OsAMT1.1 exhibited increased OsAMT1.1 expression and 15NH_(4)^(+)influx in roots under both 2.0 mmol/L NO_(3)^(-)+0.5 mmol/L NH_(4)^(+)and 0.5 mmol/L NO_(3)^(-)+2.0 mmol/L NH_(4)^(+)conditions.Our study showed that expression of OsAMT1.1 can be promoted when driven by the OsNAR2.1 promoter,especially under high-level nitrate condition,leading to enhancement of NH_(4)^(+)uptake,N use efficiency and grain yield.

Increased nitrogen use efficiency via amino acid remobilization from source to sink organs in Brassica napus

Nitrogen(N)is an essential plant growth nutrient whose coordinated distribution from source to sink organs is crucial for seed development and overall crop yield.We compared high and low N use efficiency(NUE)Brassica napus(rapeseed)genotypes.Metabonomics and transcriptomics revealed that leaf senescence induced by N deficiency promoted amino acid allocation from older to younger leaves in the high-NUE genotype at the vegetative growth stage.Efficient source to sink remobilization of amino acids elevated the numbers of branches and pods per plant under a N-deficiency treatment during the reproductive stage.A15N tracer experiment confirmed that more amino acids were partitioned into seeds from the silique wall during the pod stage in the high-NUE genotype,owing mainly to variation in genes involved in organic N transport and metabolism.We suggest that the greater amino acid source-to-sink allocation efficiency during various growth stages in the high-NUE genotype resulted in higher yield and NUE under N deficiency.These findings support the hypothesis that strong amino acid remobilization in rapeseed leads to high yield,NUE,and harvest index.

Water and nitrogen footprint assessment of integrated agronomic practice management in a summer maize cropping system

The footprints of water and nitrogen(WF and NF)provide a comprehensive overview of the type and quantity of water consumption and reactive nitrogen(Nr)loss in crop production.In this study,a field experiment over two years(2019 and 2020)compared three integrated agronomic practice management(IAPM)systems:An improved management system(T2),a high-yield production system(T3),and an integrated soil-crop management system(ISCM)using a local smallholder farmer’s practice system(T1)as control,to investigate the responses of WF,Nr losses,water use efficiency(WUE),and nitrogen use efficiency(NUE)to IAPM.The results showed that IAPM optimized water distribution and promoted water use by summer maize.The evapotranspiration over the whole maize growth period of IAPM increased,but yield increased more,leading to a significant increase in WUE.The WUE of the T2,T3,and ISCM treatments was significantly greater than in the T1 treatment,in 2019 and 2020respectively,by 19.8-21.5,31.8-40.6,and 34.4-44.6%.The lowest WF was found in the ISCM treatment,which was 31.0%lower than that of the T1 treatment.In addition,the ISCM treatment optimized soil total nitrogen(TN)distribution and significantly increased TN in the cultivated layer.Excessive nitrogen fertilizer was applied in treatment T3,producing the highest maize yield,and resulting in the highest Nr losses.In contrast,the ISCM treatment used a reduced nitrogen fertilizer rate,sacrificing grain yield partly,which reduced Nr losses and eventually led to a significant increase in nitrogen use efficiency and nitrogen recovery.The Nr level in the ISCM treatment was34.8%lower than in the T1 treatment while NUE was significantly higher than in the T1 treatment by 56.8-63.1%in2019 and 2020,respectively.Considering yield,WUE,NUE,WF,and NF together,ISCM should be used as a more sustainable and clean system for sustainable production of summer maize.

Regulation of 2-acetyl-1-pyrroline and grain quality in early-season indica fragrant rice by nitrogen and silicon fertilization under different plantation methods

Fragrant rice has a high market value,and it is a popular rice type among consumers owing to its pleasant flavor.Plantation methods,nitrogen(N)fertilizers,and silicon(Si)fertilizers can affect the grain yield and fragrance of fragrant rice.However,the core commercial rice production attributes,namely the head rice yield(HRY)and 2-acetyl-1-pyrroline(2-AP)content of fragrant rice,under various nitrogen and silicon(N-Si)fertilization levels and different plantation methods remain unknown.The field experiment in this study was performed in the early seasons of 2018 and 2019 with two popular indica fragrant rice cultivars(Yuxiangyouzhan and Xiangyaxiangzhan).They were grown under six N-Si fertilization treatments(combinations of two levels of Si fertilizer,0 kg Si ha^(−1)(Si0)and 150 kg Si ha^(−1)(Si1),and three levels of N fertilizer,0 kg N ha^(−1)(N0),150 kg N ha^(−1)(N1),and 220 kg N ha^(−1)(N2))and three plantation methods(artificial transplanting(AT),mechanical transplanting(MT),and mechanical direct-seeding(MD)).The results showed that the N-Si fertilization treatments and all the plantation methods significantly affected the HRY and 2-AP content and related parameters of the two different fragrant rice cultivars.Compared with the Si0N0 treatment,the N-Si fertilization treatments resulted in higher HRY and 2-AP contents.The rates of brown rice,milled rice,head rice,and chalky rice of the fragrant rice also improved with the N-Si fertilization treatments.The N-Si fertilization treatments increased the activities of N metabolism enzymes and the accumulation of N and Si in various parts of the fragrant rice,and affected their antioxidant response parameters.The key parameters for the HRY and 2-AP content were assessed by redundancy analysis.Furthermore,the structural equation model revealed that the Si and N accumulation levels indirectly affected the HRY by affecting the N metabolism enzyme activity,N use efficiency,and grain quality of fragrant rice.Moreover,high N and Si accumulation directly promoted the 2-AP content or affected the antioxidant response parameters and indirectly regulated 2-AP synthesis.The interactions of the MT method with the N-Si fertilization treatments varied in the fragrant rice cultivars in terms of the HRY and 2-AP content,whereas the MD method was beneficial to the 2-AP content in both fragrant rice cultivars under the N-Si fertilization treatments.

Identification of the lysine and histidine transporter family in Camellia sinensis and the characterizations in nitrogen utilization

In plants,the lysine and histidine transporter(LHT)family represent a class of proteins that mediate the uptake,translocation,and utilization of amino acids.The tea plant(Camellia sinensis)is a perennial evergreen with a relatively high level of amino acids.However,systematic identification and molecular characterization of the LHT gene family has rarely been reported in tea plants.In this study,22 CsLHTs were identified from the‘Shuchazao’genome and classified into two groups.The modeled three-dimensional structure and the conserved domains presented a high similarity among the LHTs proteins.Moreover,it was predicted that a few genes were conserved through the analysis of the physiochemical characters,structures and cis-elements in promoters.The expression patterns in tea plants revealed that CsLHT7 was mainly expressed in the roots,and CsLHT4 and CsLHT11 exhibited relatively high expression in both the roots and leaves.Moreover,the expression of all three genes could be induced by organic nitrogen.Additionally,heterogeneous expression of CsLHT4,CsLHT7 and CsLHT11 in Arabidopsis thaliana decreased the aerial parts biomass compared with that in WT plants while significantly increased the rosette biomass only for CsLHT11transgenic plants versus WT plants.Overall,our results provide fundamental information about CsLHTs and potential genes in N utilization for further analysis in tea plants.

Microfluidic-oriented synthesis of enriched iridium nanodots/carbon architecture for robust electrocatalytic nitrogen fixation

Electrocatalytic nitrogen reduction reaction(NRR)is considered as a promising candidate to achieve ammonia synthesis because of clean electric energy,moderate reaction condition,safe operating process and harmless by-products.However,the chemical inertness of nitrogen and poor activated capacity on catalyst surface usually produce low ammonia yield and faradic efficiency.Herein,the microfluidic technology is proposed to efficiently fabricate enriched iridium nanodots/carbon architecture.Owing to in-situ co-precipitation reaction and microfluidic manipulation,the iridium nanodots/carbon nanomaterials possess small average size,uniform dispersion,high conductivity and abundant active sites,producing good proton activation and rapid electrons transmission and moderate adsorption/desorption capacity.As a result,the as-prepared iridium nanodots/carbon nanomaterials realize large ammonia yield of 28.73 μg h^(-1) cm^(-2) and faradic efficiency of 9.14%in KOH solution.Moreover,the high ammonia yield of 11.21 μg h^(-1) cm^(-2) and faradic efficiency of 24.30%are also achieved in H_(2)SO_(4) solution.The microfluidic method provides a reference for large-scale fabrication of nano-sized catalyst materials,which may accelerate the progress of electrocatalytic NRR in industrialization field.

Smart Interfacing between Co-Fe Layered Double Hydroxide and Graphitic Carbon Nitride for High-efficiency Electrocatalytic Nitrogen Reduction

Bimetallic compounds such as hydrotalcite-type layered double hydroxides(LDHs)are promising electrocatalysts owing to their unique electronic structures.However,their abilities toward nitrogen adsorption and reduction are undermined since the surface-mantled,electronegative-OH groups hinder the charge transfer between transition metal atoms and nitrogen molecules.Herein,a smart interfacing strategy is proposed to construct a coupled heterointerface between LDH and 2D g-C_(3)N_(4),which is proven by density functional theory(DFT)investigations to be favorable for nitrogen adsorption and ammonia desorption compared with neat LDH surface.The interfaced LDH and g-C_(3)N_(4) is further hybridized with a self-standing TiO_(2) nanofibrous membrane(NM)to maximize the interfacial effect owing to its high porosity and large surface area.Profited from the synergistic superiorities of the three components,the LDH@C_(3)N_(4)@TiO_(2) NM delivers superior ammonia yield(2.07×10^(−9) mol s^(−1) cm^(−2))and Faradaic efficiency(25.3%),making it a high-efficiency,noble-metal-free catalyst system toward electrocatalytic nitrogen reduction.

Distribution Characteristics of Soil Total Nitrogen in Low-efficiency Forest Land in the Northern Windy Desert Area of Jingbian County

[Objectives]The paper was to investigate the distribution characteristics of soil total nitrogen in low-efficiency forest land in the northern windy desert area of Jingbian County.[Methods]The distribution of soil total nitrogen in the 0-40 cm soil layer of 5 towns in the northern windy desert area of Jingbian County was studied through field sampling and laboratory detection.[Results]The average soil total nitrogen contents of Hongdunjie Town,Haizetan Town,Huanghaojie Town,Ningtiaoliang Town,Dongkeng Town and windy desert area in the 0-20 cm soil layer were 0.259,0.224,0.242,0.248,0.431 and 0.275 g/kg,respectively.The soil total nitrogen content in Dongkeng Town was higher than those in other towns,while there was little difference among other regions.The average total nitrogen contents in the 20-40 cm soil layer were 0.239,0.285,0.113,0.262,0.349 and 0.241 g/kg,respectively.The soil total nitrogen content in Huanghaojie Town was slightly lower than those in other towns,while that in Dongkeng town was higher.The variation coefficient of soil total nitrogen content in the survey area was greater than 30%,and there was great difference in spatial distribution.With the increase of soil depth,there was little change in soil total nitrogen content,namely the soil total nitrogen contents in 5 towns and windy desert area were not statistically different in the 0-40 cm soil layer.According to the nutrient grading standard of the second national soil survey,the soil total nitrogen content in the survey area was in the deficiency grade.[Conclusions]The research will provide a scientific guidance for the healthy and sustainable development of vegetation in arid regions.