Nitrogen is one of the essential nutrient elements for plant growth,which plays an important role in the growth and development of sugarcane. The whole growth cycle of sugarcane needs a large amount of nitrogen. Incre...Nitrogen is one of the essential nutrient elements for plant growth,which plays an important role in the growth and development of sugarcane. The whole growth cycle of sugarcane needs a large amount of nitrogen. Increasing the application of nitrogen can improve the yield of sugarcane,but it will also cause environmental pollution. Therefore,how to control or reduce the application of nitrogen fertilizer while continuously increasing sugarcane yield,reduce the increase of sugarcane production cost and environmental pollution caused by excessive application of nitrogen fertilizer has become an important scientific problem faced by sugarcane industry in China.^15N stable isotope labeling technology has been applied to many crops as a nitrogen research tool. In order to better understand the demand of nitrogen fertilizer in soil-cane system,this paper reviewed nitrogen allocation in plants,nitrogen loss,nitrogen recycling and endogenous nitrogen fixation of sugarcane based on^15N stable isotope labeling technology used in the nitrogen uptake and utilization,providing a theoretical basis for the improvement of sugarcane nitrogen use efficiency and the efficient nitrogen fertilizer management of sugarcane.展开更多
[ Objective] The study aimed to reveal the biological nitrogen fixation capacity by sugarcane from Brazil under the ecological conditions of Guangxi, and to provide reference for study on the biological nitrogen fixat...[ Objective] The study aimed to reveal the biological nitrogen fixation capacity by sugarcane from Brazil under the ecological conditions of Guangxi, and to provide reference for study on the biological nitrogen fixation capacity by sugarcane and related generalization and application. [ Method] The ^15N isotopic fertilizer was solely applied on plants of three sugarcane cultivars planted in greenhouse with no other fertilizer forms applied, meanwhile virus-free stem seedling was regarded as control, to measure their biological nitrogen fixation capacity using ^15N isotope. [ Result ] The nitrogen fixation rate of B8 from Brazil reached 26.91%, while Guitang 11 and RIC16 presented no or poor nitrogen fixation capacity. [ Conclusion] The sugarcane eultivar B8 from Brazil showed some nitrogen fixation capacity under the ecological conditions of Guangxi.展开更多
Nitrogen （N） use efficiency is usually less than 50%, and it remains a major problem in rice cultivation. Controlled release fertilizer （CRF） technology is one of the well-known efforts to overcome this problem. T...Nitrogen （N） use efficiency is usually less than 50%, and it remains a major problem in rice cultivation. Controlled release fertilizer （CRF） technology is one of the well-known efforts to overcome this problem. The efficiency of CRF, however, is very much dependent on the timing of nutrient release. This study was conducted to determine the precise time of N uptake by rice as a guideline to develop efficient CRF. Fertilizer N uptake by rice at different growth stages was investigated by using 15N isotopic technique. Rice was planted in pots, with 15N urea as N source at the rate of 120 kg/hm2. Potassium and phosphorus were applied at the same rate of 50 kg/hm2. Standard agronomic practices were employed throughout the growing periods. Rice plants were harvested every two weeks until maturation at the 14th week and analyzed for total N and 15N content. Nitrogen derived from fertilizer was calculated. Total N uptake in plants consistently increased until the 11th week. After that, it started to plateau and finally declined. Moreover, N utilization by rice plants peaked at 50%, which occurred during the 11th week after transplanting. N derived from fertilizer in rice plants were in the range of 18.7% to 40.0% in all plant tissues. The remaining N was derived from soil. Based on this study, N release from CRF should complete by the 11th week after planting to ensure the maximum fertilizer N uptake by rice plants. Efficient CRF should contribute to higher N derived from fertilizer which also resulted in a higher total N uptake by rice plants, increasing the potential of rice to produce higher yield while at the same time of reducina loss.展开更多
In this study,the nitrogen removal performance of partial denitrificaiton/anammox(PDA)process was investigated by using an UASB reactor.High total nitrogen(TN)removal efficiency(91.97%)was achieved at an influent nitr...In this study,the nitrogen removal performance of partial denitrificaiton/anammox(PDA)process was investigated by using an UASB reactor.High total nitrogen(TN)removal efficiency(91.97%)was achieved at an influent nitrogen loading rate of 0.64 kg/(m3·d).Anammox bacteria did execute the function of converting nitrate to nitrite in PDA system according to ^(15)N isotope labeling experiments and the contribution was approximately 36.3%.Candidatus_Brocadia,Candidatus_Kuenenia and Thauera were functional strains for anammox and denitrification process,respectively.Thauera and Candidatus_Brocadia were more important for TN removal at high loading rates(0.64 kg/(m3·d)).This result can provide a theoretical and technical foundation for the application of the PDA process.展开更多
Shijiazhuang City is the capital of Hebei province, China. Groundwater is the major water supply source for living and industry need of the city. Due to a rapid increase of population and development of industry and a...Shijiazhuang City is the capital of Hebei province, China. Groundwater is the major water supply source for living and industry need of the city. Due to a rapid increase of population and development of industry and agriculture, a series of groundwater environmental problems are created. In the paper, the situation of groundwater pollution in Shijiazhuang city is reported. Based on the groundwater chemical data and ^(15)N measurement results both on groundwater and soils, the reason of groundwater nitra...展开更多
The high-resolution absorption spectra of the （2,0）,（3,1）,and （8,5） bands of the A^2Π^u-X^2∑g^＋ system of ^15N2^＋ have been recorded by using velocity modulation spectroscopy technique in the near infrared r...The high-resolution absorption spectra of the （2,0）,（3,1）,and （8,5） bands of the A^2Π^u-X^2∑g^＋ system of ^15N2^＋ have been recorded by using velocity modulation spectroscopy technique in the near infrared region.The rotational constants of the X^2∑g^＋ and A^2Πu states of ^15N2^＋ were derived from the spectroscopic data.The isotope shifts of these bands of the A^2Πu-X^2∑g^＋ system of ^14N2^＋ and ^15N2^＋ were also analyzed and discussed.展开更多
Ectomycorrhizal(EM)networks provide a variety of services to plants and ecosystems include nutrient uptake and transfer,seedling survival,internal cycling of nutrients,plant competition,and so on.To deeply their struc...Ectomycorrhizal(EM)networks provide a variety of services to plants and ecosystems include nutrient uptake and transfer,seedling survival,internal cycling of nutrients,plant competition,and so on.To deeply their structure and function in ecosystems,we investigated the spatial patterns and nitrogen(N)transfer of EM networks usingN labelling technique in a Mongolian scotch pine(Pinus sylvestris var.mongolica Litv.)plantation in Northeastern China.In August 2011,four plots(20 × 20 m)were set up in the plantation.125 ml 5 at.%0.15 mol/LNHNOsolution was injected into soil at the center of each plot.Before and 2,6,30 and 215 days after theN application,needles(current year)of each pine were sampled along four 12 m sampling lines.Needle total N andN concentrations were analyzed.We observed needle N andN concentrations increased significantly over time afterN application,up to 31 and0.42%,respectively.There was no correlation between needle N concentration andN/N ratio(R2=0.40,n=5,P=0.156),while excess needle N concentration and excess needleN/N ratio were positively correlated across different time intervals(R~2=0.89,n=4,P\0.05),but deceased with time interval lengthening.NeedleN/N ratio increased with time,but it was not correlated with distance.NeedleN/N ratio was negative with distance before and 6th day and 30th day,positive with distance at 2nd day,but the trend was considerably weaker,their slop were close to zero.These results demonstrated that EM networks were ubiquitous and uniformly distributed in the Mongolian scotch pine plantation and a random network.We found N transfer efficiency was very high,absorbed N by EM network was transferred as wide as possible,we observed N uptake of plant had strong bias forN andN,namely N fractionation.Understanding the structure and function of EM networks in ecosystems may lead to a deeper understanding of ecological stability and evolution,and thus provide new theoretical approaches to improve conservation practices for the management of the Earth’s ecosystems.展开更多
The lower availability of N is one of the most important limiting factors impeding crop yield enhancement among the various factors that affect crop yield under the multiple-cropping agroecosystem in China.In this stu...The lower availability of N is one of the most important limiting factors impeding crop yield enhancement among the various factors that affect crop yield under the multiple-cropping agroecosystem in China.In this study,the recovery of a single application of 15N-labeled fertilizer or residues in rice-wheat cropping system was determined,in order to provide theoretical foundation for the nitrogen management in sustainable agricultural production.A continuous trace experiment was conducted for 15N microplots by using randomized block design with four treatments and four replications（T1 = 15N-labeled fertilizer with crop residue incorporation,T2 = 15N-labeled residues,T3 = 14N fertilizer to generate unlabeled crop residue,and T4 = 15Nlabeled fertilizer without crop residue incorporation）.Our results showed that,on average,17.17 and 12.01% of crop N was derived from N fertilizer and 15N-labeled residues,respectively during the first growing season,suggesting that approximately 82.83 or 87.99% of crop N was derived directly from soil N pool.There was a larger difference in the 15N recovery pattern in crop when N was applied as fertilizer or residues,i.e.,most of crop N derived from N fertilizer was absorbed in the first growing season（92.04%）,and the relevant value was 38.03% when 15N-labeled residues were applied.This implied that most of N fertilizer was recovered in the present cropping season,while a longer residue effect will be found for 15N-labeled residues.Thus,the average recovery of N fertilizer and N residue in the soil after the first growing season was 33.46 and 85.64%,respectively.The recovery of applied N in soil when N was applied as residues was significantly higher than that when N was applied as fertilizer.There was a larger difference in the total 15N recovery in plant and soil when N was applied as fertilizer or residues.By the end of the fifth or sixth cropping season,the total 15N recovery in plant and soil when N was applied as fertilizer or residues were estimated at 64.38 and 79.11%,respectively.On the contrary,there was little difference between the practices of residue incorporation and residue removal following the N fertilizer application.N fertilizer appeared to be more readily available to crops than residue-N,and residue-N replenished soil N pool,especially N in soil organic matter,much more than N fertilizer after six growing seasons.Therefore,residue-N is a better source for sustaining N content of soil organic matter.Thus,one possible management practice is to use both organic and inorganic N sources simultaneously to improve the use efficiency of N while protecting the sustainability of soil.展开更多
In the present study, we report N2 fixation rate(15N isotope tracer assay) and the diazotroph community structure(using the molecular method) in the western tropical North Pacific Ocean(WTNP)(13°–20°N, 120&...In the present study, we report N2 fixation rate(15N isotope tracer assay) and the diazotroph community structure(using the molecular method) in the western tropical North Pacific Ocean(WTNP)(13°–20°N, 120°–160°E). Our independent evidence on the basis of both in situ N2 fixation activity and diazotroph community structure showed the dominance of unicellular N2 fixation over majority of the WTNP surface waters during the sampling periods.Moreover, a shift in the diazotrophic composition from unicellular cyanobacteria group B-dominated to Trichodesmium spp.-dominated toward the western boundary current(Kuroshio) was also observed in 2013. We hypothesize that nutrient availability may have played a major role in regulating the biogeography of N2 fixation.In surface waters, volumetric N2 fixation rate(calculated by nitrogen) ranged between 0.6 and 2.6 nmol/(L·d) and averaged(1.2±0.5) nmol/(L·d), with <10 μm size fraction contributed predominantly(88%±6%) to the total rate between 135°E and 160°E. Depth-integrated N2 fixation rate over the upper 200 m ranged between 150 μmol/(m^2·d)and 480 μmol/(m^2·d)average(225±105) μmol/(m^2·d). N2 fixation can account for 6.2%±3.7% of the depthintegrated primary production, suggesting that N2 fixation is a significant N source sustaining new and export production in the WTNP. The role of N2 fixation in biogeochemical cycling in this climate change-vulnerable region calls for further investigations.展开更多
The Paleocene coals of the Salt Range in the Punjab Province of Pakistan have great economic potential;however,their trace element and stable isotopic characteristics have not been studied in detail except for a few s...The Paleocene coals of the Salt Range in the Punjab Province of Pakistan have great economic potential;however,their trace element and stable isotopic characteristics have not been studied in detail except for a few sporadic samples.In this study,a total of 59 coal samples of which 14 are obtained from open cast mines have been investigated for elemental composition andδ^(13)C-δ^(15)N isotopic signatures.Average contents of trace elements such as Co,Cr,Cu,Pb,Sr,Th,U,V,and Zn are 7.4,41.7,11.2,12.5,90.2,4.0,1.9,128,and 31.1 mg/kg,respectively.These values,when compared with the World Coal Clarke values,were relatively higher in low-rank coals in comparison with Clarke values for brown coals.Likewise,As(20.4 mg/kg),Co(6.6 mg/kg),Cr(22.4 mg/kg),Cu(^(13).3 mg/kg),Pb(19.2 mg/kg),Sr(^(15)4.7 mg/kg),Th(2.5 mg/kg),V(47.8 mg/kg),and Zn(75.1 mg/kg)were significantly higher in the sub-bituminous to bituminous coals of the Salt Range.Mineralogical analysis,based on X-ray diffraction and energy dispersive X-ray spectroscopy,revealed that the studied samples contain illite,kaolinite calcite,gypsum,pyrite,and quartz.Elemental affinity with organic and inorganic phases of coals calculated by an indirect statistical approach indicated a positive association of ash content with Ag,Al,Co,Cr,Cs,Cu,Mn,P,Rb,Pb,Th,U,and V,suggesting the presence of inorganic components in studied coals.However,As,Fe,Sr,and Zn exhibit negative correlations that imply their association with the organic fraction.Theδ^(13)C andδ^(15)N isotopic range and average−24.94‰to−25.86‰(−25.41‰)and−2.77‰to 3.22‰(0.96‰),respectively,reflecting 3C type modern terrestrial vegetation were common in the palaeomires of studied coal seams.In addition,the trivial variations of 0.92‰and 0.45‰among^(13)C and^(15)N values can be attributed to water level fluctuations and plant assemblies.展开更多
A knowledge of the tree-ring stable nitrogen isotope ratio(δ^(15)N)can deepen our understanding of forest ecosystem dynamics by indicating the long-term availability,cycling and sources of nitrogen(N).However,the rad...A knowledge of the tree-ring stable nitrogen isotope ratio(δ^(15)N)can deepen our understanding of forest ecosystem dynamics by indicating the long-term availability,cycling and sources of nitrogen(N).However,the radial mobility of N blurs the interannual variations in the long-term N records.Previous studies of the chemical extraction of tree rings before analysis had produced inconsistent results and it is still unclear whether it is necessary to pre-treat wood samples from specific tree species to remove soluble N compounds before determining theδ^(15)N values.We compared the effects of pre-treatment with organic solvents and hot ultrapure water on the N concentration andδ^(15)N of tree rings from endemic Qinghai spruce(Picea crassifolia)growing in the interior of the central Qilian Mountains,China,during the last 60 a.We assessed the effects of different preparation protocols on the removal of the labile N compounds and investigated the need to pre-treat wood samples before determining theδ^(15)N values of tree rings.Increasing trends of the tree-ring N concentration were consistently observed in both the extracted and unextracted wood samples.The total N removed by extraction with organic solvents was about 17.60%,with a significantly higher amount in the sapwood section(P<0.01).Theδ^(15)N values of tree rings decreased consistently from 1960 to 2019 in both the extracted and unextracted wood samples.Extraction with organic solvents increased theδ^(15)N values markedly by about 5.2‰and reduced the variations in theδ^(15)N series.However,extraction with hot ultrapure water had little effect,with only a slight decrease in theδ^(15)N values of about 0.5‰.Our results showed that the radial pattern in the inter-ring movement of N in Qinghai spruce was not minimized by extraction with either organic solvents or hot ultrapure water.It is unnecessary to conduct hot ultrapure water extraction for the wood samples from Qinghai spruce because of its negligible effect on the removal of the labile N.Theδ^(15)N variation trend of tree rings in the unextracted wood samples was not influenced by the heartwood-sapwood transition zone.We suggest that theδ^(15)N values of the unextracted wood samples of the climate-sensitive Qinghai spruce could be used to explore the ecophysiological dynamics while focusing on the long-term variations.展开更多
Aims Mycorrhizas(fungal roots)play vital roles in plant nutrient acquisition,performance and productivity in terrestrial ecosystems.Arbuscular mycorrhizas(AM)and ectomycorrhizas(EM)are mostly important since soil nutr...Aims Mycorrhizas(fungal roots)play vital roles in plant nutrient acquisition,performance and productivity in terrestrial ecosystems.Arbuscular mycorrhizas(AM)and ectomycorrhizas(EM)are mostly important since soil nutrients,including NH+4,NO3 and phosphorus,are translocated from mycorrhizal fungi to plants.Individual species,genera and even families of plants could be interconnected by mycorrhizal mycelia to form common mycorrhizal networks(CMNs).The function of CMNs is to provide pathways for movement or transfer of nutrients from one plant to another.In the past four decades,both ^(15)N external labeling or enrichment(usually expressed as atom%)and ^(15)N naturally occurring abundance(d^(15)N,&)techniques have been employed to trace the direction and magnitude of N transfer between plants,with their own advantages and limitations.Important Findings The heavier stable isotope ^(15)N is discriminated against 14N during biochemical,biogeochemical and physiological processes,due to a greater atomic mass.In general,non-N2-fixing plants had greater d^(15)N values than N2-fixing(;0&)ones.Foliar d^(15)N often varied by 5 to 10&in the order:non-mycorrhizas/AMs>EMs>ericoid mycorrhizas.Differences in d^(15)N(&)or ^(15)N(atom%)values could thus provide N transfer information between plants.A range of between 0 to 80%of one-way N transfer had been observed from N2-fixing mycorrhizal to non-N2-fixing mycorrhizal plants,but generally less than or around 10%in the reverse direction.Plant-to-plant N transfer may provide practical implications for plant performance in N-limited habitats.Considering that N translocation or cycling is crucial,and the potential benefits of N transfer are great in both agricultural and natural ecosystems,more research is warranted on either oneway or two-way N transfers mediated by CMNs with different species and under field conditions.展开更多
In this study,aluminum-based P-inactivation agent(Al-PIA)was used as a high-efficiency microbial carrier,and the biological Al-PIA(BA-PIA)was prepared by artificial aeration.Laboratory static experiments were conducte...In this study,aluminum-based P-inactivation agent(Al-PIA)was used as a high-efficiency microbial carrier,and the biological Al-PIA(BA-PIA)was prepared by artificial aeration.Laboratory static experiments were conducted to study the effect of BA-PIA on reducing nitrogen and phosphorus contents in water.Physicochemical characterization and isotope tracing method were applied to analyze the removal mechanism of nitrogen and phosphorus.High-throughput techniques were used to analyze the characteristic bacterial genus in the BA-PIA system.The nitrogen and phosphorus removal experiment was conducted for 30 days,and the removal rates of NH_(4)^(+)-N,TN and TP by BA-PIA were 81.87%,66.08%and 87.97%,respectively.The nitrogen removal pathways of BA-PIA were as follows:the nitrification reaction accounted for 59.0%(of which denitrification reaction accounted for 56.4%),microbial assimilation accounted for 18.1%,and the unreacted part accounted for 22.9%.The characteristic bacteria in the BA-PIA system were Streptomyces,Nocardioides,Saccharopolyspora,Nitrosomonas,and Marinobacter.The loading of microorganisms only changed the surface physical properties of Al-PIA(such as specific surface area,pore volume and pore size),without changing its surface chemical properties.The removal mechanism of nitrogen by BA-PIA is the conversion of NH_(4)^(+)-N into NO_(2)^(−)-N and NO_(3)^(−)-N by nitrifying bacteria,which are then reduced to nitrogen-containing gas by aerobic denitrifying bacteria.The phosphorus removal mechanism is that metal compounds(such as Al)on the surface of BA-PIA fix phosphorus through chemisorption processes,such as ligand exchange.Therefore,BA-PIA overcomes the deficiency of Al-PIA with only phosphorus removal ability,and has better application prospects.展开更多
Ethylene participates in the regulation of numerous cellular events and biological processes, including wa- ter loss, during leaf and flower petal wilting. The diverse ethylene responses may be regulated via dynamic i...Ethylene participates in the regulation of numerous cellular events and biological processes, including wa- ter loss, during leaf and flower petal wilting. The diverse ethylene responses may be regulated via dynamic interplays between protein phosphorylation/dephosphorylation and ubiquitin/26S proteasome-mediated protein degradation and protease cleavage. To address how ethylene alters protein phosphorylation through multi-furcated signaling pathways, we performed a lSN stable isotope labelling-based, differential, and quantitative phosphoproteomics study on air- and ethylene-treated ethylene-insensitive Arabidopsis double loss-of-function mutant ein3-1/eill-1. Among 535 non-redundant phosphopeptides identified, two and four phosphopeptides were up- and downregulated by ethylene, respectively. Ethylene- regulated phosphorylation of aquaporin PIP2;1 is positively correlated with the water flux rate and water loss in leaf. Genetic studies in combination with quantitative proteomics, immunoblot analysis, protoplast swelling/shrinking experiments, and leaf water loss assays on the transgenic plants expressing both the wild-type and S280A/S283A-mutated PIP2;1 in the both Col-O and ein3eill genetic backgrounds suggest that ethylene increases water transport rate in Arabidopsis cells by enhancing S280/S283 phosphorylation at the C terminus of PIP2;1. Unknown kinase and/or phosphatase activities may participate in the initial up- regulation independent of the cellular functions of EIN3/EIL1. This finding contributes to our understanding of ethylene-regulated leaf wilting that is commonly observed during post-harvest storage of plant organs.展开更多
Combined application of biochar with fertilizers has been used to increase soil fertility and crop yield.However,the coupling mechanisms through which biochar improves crop yield at field scale and the time span over ...Combined application of biochar with fertilizers has been used to increase soil fertility and crop yield.However,the coupling mechanisms through which biochar improves crop yield at field scale and the time span over which biochar affects carbon and nitrogen transformation and crop yield are still little known.In this study,a long-term field trial(2013-2019)was performed in brown soil planting maize.Six treatments were designed:CK-control;NPK-application of chemical fertilizers;C1PK-low biochar without nitrogen fertilizer;C1NPK,C_(2)NPK and C_(3)NPK-biochar at 1.5,3 and 6 t ha^(−1),respectively,combined with chemical fertilizers.Results showed that theδ^(15)N value in the topsoil of 0-20 cm layer in the C_(3)NPK treat-ment reached a peak of 291‰at the third year(2018),and demonstrated a peak of 402‰in the NPK treatment in the initial isotope trial in 2016.Synchronously,SOC was not affected until the third to fourth year after biochar addition,and resulted in a significant increase in total N of 2.4 kg N ha^(−1) in 2019 in C_(3)NPK treatment.During the entire experiment,the ^(15)N recovery rates of 74-80%were observed highest in the C_(2)NPK and C_(3)NPK treatments,resulting in an annual increase in yields significantly.The lowest subsoilδ^(15)N values ranged from 66‰to 107‰,and the ^(15)N residual rate would take 70 years for a complete decay to 0.001%in the C_(3)NPK.Our findings suggest that biochar compound fertilizers can increase C stability and N retention in soil and improve N uptake by maize,while the loss of N was minimized.Biochars,therefore,may have an important potential for improving the agroecosystem and ecological balance.展开更多
Biochar amendment of soil may ameliorate inherently infertile soils,such as in the typical coconut(Cocos nucifera L.)growth areas along tropical coasts,where,moreover,temporary moisture stress commonly occurs.We condu...Biochar amendment of soil may ameliorate inherently infertile soils,such as in the typical coconut(Cocos nucifera L.)growth areas along tropical coasts,where,moreover,temporary moisture stress commonly occurs.We conducted a pot experiment to evaluate the effects of biochar soil amendment(1%w/w)produced from Gliricidia sepium stems(BC-Gly)and rice husks(BC-RiH)on the growth of coconut seedlings and on N and P uptake mediated by mycorrhizae under wet or dry conditions in a Sandy Regosol.The pots were divided into root and hyphal zones by a nylon mesh,where 15N labelled N and P nutrients were only provided in the hyphal zone.Under wet conditions,biochar applica-tion did not affect plant growth,while under dry conditions,the BC-Gly increased root and plant growth similar to that under wet conditions.BC-Gly increased the acidic pH of the soil to a neutral level,and the microbial community shifted towards a higher fungal abundance.The P accumulated(Pacc)in roots was higher with BC-Gly and BC-RiH under dry and wet conditions,respectively.Pacc weakly correlated with the abundance of arbuscular mycorrhizal fungi(AMF)in the hyphal zone.With BC-Gly roots showed lower N derived from fertilizer.We conclude that biochar application has no impact on crop growth under wet conditions,while under dry conditions,BC-Gly stimulates crop growth and P uptake,probably through liming induced P availability but also possibly by some enhancement of AMF growth.The shift in the fungal-oriented microbial community and reduced plant fertilizer N uptake suggested that BC-Gly acted as an additional N source.展开更多
基金Supported by National Natural Science Foundation of China(31860350)Guangxi Project(GK AA17202042-6)+2 种基金Earmarked Fund for China Agriculture Research System(CARS-170105)Guangxi Innovation Team Program(gjnytxgxcxtd-03-01)Fund of Guangxi Academy of Agricultural Sciences(GNK2018YT02,2018YM01,2020YM24)。
文摘Nitrogen is one of the essential nutrient elements for plant growth,which plays an important role in the growth and development of sugarcane. The whole growth cycle of sugarcane needs a large amount of nitrogen. Increasing the application of nitrogen can improve the yield of sugarcane,but it will also cause environmental pollution. Therefore,how to control or reduce the application of nitrogen fertilizer while continuously increasing sugarcane yield,reduce the increase of sugarcane production cost and environmental pollution caused by excessive application of nitrogen fertilizer has become an important scientific problem faced by sugarcane industry in China.^15N stable isotope labeling technology has been applied to many crops as a nitrogen research tool. In order to better understand the demand of nitrogen fertilizer in soil-cane system,this paper reviewed nitrogen allocation in plants,nitrogen loss,nitrogen recycling and endogenous nitrogen fixation of sugarcane based on^15N stable isotope labeling technology used in the nitrogen uptake and utilization,providing a theoretical basis for the improvement of sugarcane nitrogen use efficiency and the efficient nitrogen fertilizer management of sugarcane.
基金National Natural Science Foundation of China (3026005430660085)+1 种基金Key Project of Guangxi Academy of Agricultural Sciences (2004002)Natural Science Foundation in Guangxi Zhuang Autonomous Region (0639011)~~
文摘[ Objective] The study aimed to reveal the biological nitrogen fixation capacity by sugarcane from Brazil under the ecological conditions of Guangxi, and to provide reference for study on the biological nitrogen fixation capacity by sugarcane and related generalization and application. [ Method] The ^15N isotopic fertilizer was solely applied on plants of three sugarcane cultivars planted in greenhouse with no other fertilizer forms applied, meanwhile virus-free stem seedling was regarded as control, to measure their biological nitrogen fixation capacity using ^15N isotope. [ Result ] The nitrogen fixation rate of B8 from Brazil reached 26.91%, while Guitang 11 and RIC16 presented no or poor nitrogen fixation capacity. [ Conclusion] The sugarcane eultivar B8 from Brazil showed some nitrogen fixation capacity under the ecological conditions of Guangxi.
基金Long-Term Research Grant Scheme of the Ministry of Education, Malaysia under the project ‘One BAJA: The Next Generation Green and Economical Urea’
文摘Nitrogen （N） use efficiency is usually less than 50%, and it remains a major problem in rice cultivation. Controlled release fertilizer （CRF） technology is one of the well-known efforts to overcome this problem. The efficiency of CRF, however, is very much dependent on the timing of nutrient release. This study was conducted to determine the precise time of N uptake by rice as a guideline to develop efficient CRF. Fertilizer N uptake by rice at different growth stages was investigated by using 15N isotopic technique. Rice was planted in pots, with 15N urea as N source at the rate of 120 kg/hm2. Potassium and phosphorus were applied at the same rate of 50 kg/hm2. Standard agronomic practices were employed throughout the growing periods. Rice plants were harvested every two weeks until maturation at the 14th week and analyzed for total N and 15N content. Nitrogen derived from fertilizer was calculated. Total N uptake in plants consistently increased until the 11th week. After that, it started to plateau and finally declined. Moreover, N utilization by rice plants peaked at 50%, which occurred during the 11th week after transplanting. N derived from fertilizer in rice plants were in the range of 18.7% to 40.0% in all plant tissues. The remaining N was derived from soil. Based on this study, N release from CRF should complete by the 11th week after planting to ensure the maximum fertilizer N uptake by rice plants. Efficient CRF should contribute to higher N derived from fertilizer which also resulted in a higher total N uptake by rice plants, increasing the potential of rice to produce higher yield while at the same time of reducina loss.
基金supported by the Natural Science Foundation of Shandong Province (ZR2019MEE038)the Fundamental Research Funds for the Central Universities (19CX02038A)the Key R&D Program of Shandong Province (Major Scientific and Technological Innovation Project 2019JZZY020502)
文摘In this study,the nitrogen removal performance of partial denitrificaiton/anammox(PDA)process was investigated by using an UASB reactor.High total nitrogen(TN)removal efficiency(91.97%)was achieved at an influent nitrogen loading rate of 0.64 kg/(m3·d).Anammox bacteria did execute the function of converting nitrate to nitrite in PDA system according to ^(15)N isotope labeling experiments and the contribution was approximately 36.3%.Candidatus_Brocadia,Candidatus_Kuenenia and Thauera were functional strains for anammox and denitrification process,respectively.Thauera and Candidatus_Brocadia were more important for TN removal at high loading rates(0.64 kg/(m3·d)).This result can provide a theoretical and technical foundation for the application of the PDA process.
基金supported by International Atomic Energy Agency (IAEA) (No. :11515/RBF)
文摘Shijiazhuang City is the capital of Hebei province, China. Groundwater is the major water supply source for living and industry need of the city. Due to a rapid increase of population and development of industry and agriculture, a series of groundwater environmental problems are created. In the paper, the situation of groundwater pollution in Shijiazhuang city is reported. Based on the groundwater chemical data and ^(15)N measurement results both on groundwater and soils, the reason of groundwater nitra...
基金supported by the National Natural Science Foundation of China(Grant No.11674096)
文摘The high-resolution absorption spectra of the （2,0）,（3,1）,and （8,5） bands of the A^2Π^u-X^2∑g^＋ system of ^15N2^＋ have been recorded by using velocity modulation spectroscopy technique in the near infrared region.The rotational constants of the X^2∑g^＋ and A^2Πu states of ^15N2^＋ were derived from the spectroscopic data.The isotope shifts of these bands of the A^2Πu-X^2∑g^＋ system of ^14N2^＋ and ^15N2^＋ were also analyzed and discussed.
基金supported by National Natural Science Foundation of China(30830024)
文摘Ectomycorrhizal(EM)networks provide a variety of services to plants and ecosystems include nutrient uptake and transfer,seedling survival,internal cycling of nutrients,plant competition,and so on.To deeply their structure and function in ecosystems,we investigated the spatial patterns and nitrogen(N)transfer of EM networks usingN labelling technique in a Mongolian scotch pine(Pinus sylvestris var.mongolica Litv.)plantation in Northeastern China.In August 2011,four plots(20 × 20 m)were set up in the plantation.125 ml 5 at.%0.15 mol/LNHNOsolution was injected into soil at the center of each plot.Before and 2,6,30 and 215 days after theN application,needles(current year)of each pine were sampled along four 12 m sampling lines.Needle total N andN concentrations were analyzed.We observed needle N andN concentrations increased significantly over time afterN application,up to 31 and0.42%,respectively.There was no correlation between needle N concentration andN/N ratio(R2=0.40,n=5,P=0.156),while excess needle N concentration and excess needleN/N ratio were positively correlated across different time intervals(R~2=0.89,n=4,P\0.05),but deceased with time interval lengthening.NeedleN/N ratio increased with time,but it was not correlated with distance.NeedleN/N ratio was negative with distance before and 6th day and 30th day,positive with distance at 2nd day,but the trend was considerably weaker,their slop were close to zero.These results demonstrated that EM networks were ubiquitous and uniformly distributed in the Mongolian scotch pine plantation and a random network.We found N transfer efficiency was very high,absorbed N by EM network was transferred as wide as possible,we observed N uptake of plant had strong bias forN andN,namely N fractionation.Understanding the structure and function of EM networks in ecosystems may lead to a deeper understanding of ecological stability and evolution,and thus provide new theoretical approaches to improve conservation practices for the management of the Earth’s ecosystems.
文摘The lower availability of N is one of the most important limiting factors impeding crop yield enhancement among the various factors that affect crop yield under the multiple-cropping agroecosystem in China.In this study,the recovery of a single application of 15N-labeled fertilizer or residues in rice-wheat cropping system was determined,in order to provide theoretical foundation for the nitrogen management in sustainable agricultural production.A continuous trace experiment was conducted for 15N microplots by using randomized block design with four treatments and four replications（T1 = 15N-labeled fertilizer with crop residue incorporation,T2 = 15N-labeled residues,T3 = 14N fertilizer to generate unlabeled crop residue,and T4 = 15Nlabeled fertilizer without crop residue incorporation）.Our results showed that,on average,17.17 and 12.01% of crop N was derived from N fertilizer and 15N-labeled residues,respectively during the first growing season,suggesting that approximately 82.83 or 87.99% of crop N was derived directly from soil N pool.There was a larger difference in the 15N recovery pattern in crop when N was applied as fertilizer or residues,i.e.,most of crop N derived from N fertilizer was absorbed in the first growing season（92.04%）,and the relevant value was 38.03% when 15N-labeled residues were applied.This implied that most of N fertilizer was recovered in the present cropping season,while a longer residue effect will be found for 15N-labeled residues.Thus,the average recovery of N fertilizer and N residue in the soil after the first growing season was 33.46 and 85.64%,respectively.The recovery of applied N in soil when N was applied as residues was significantly higher than that when N was applied as fertilizer.There was a larger difference in the total 15N recovery in plant and soil when N was applied as fertilizer or residues.By the end of the fifth or sixth cropping season,the total 15N recovery in plant and soil when N was applied as fertilizer or residues were estimated at 64.38 and 79.11%,respectively.On the contrary,there was little difference between the practices of residue incorporation and residue removal following the N fertilizer application.N fertilizer appeared to be more readily available to crops than residue-N,and residue-N replenished soil N pool,especially N in soil organic matter,much more than N fertilizer after six growing seasons.Therefore,residue-N is a better source for sustaining N content of soil organic matter.Thus,one possible management practice is to use both organic and inorganic N sources simultaneously to improve the use efficiency of N while protecting the sustainability of soil.
基金The National Basic Research Program of China under contract No.2015CB452903the Foundation of China Ocean Mineral Resources R&D Association under contract No.DY135-E2-2-03+1 种基金the Science and Technology Basic Resources Investigation Program of China under contract No.2017FY201403the National Natural Science Foundation of China under contract Nos 41676174,41206104 and 41876198
文摘In the present study, we report N2 fixation rate(15N isotope tracer assay) and the diazotroph community structure(using the molecular method) in the western tropical North Pacific Ocean(WTNP)(13°–20°N, 120°–160°E). Our independent evidence on the basis of both in situ N2 fixation activity and diazotroph community structure showed the dominance of unicellular N2 fixation over majority of the WTNP surface waters during the sampling periods.Moreover, a shift in the diazotrophic composition from unicellular cyanobacteria group B-dominated to Trichodesmium spp.-dominated toward the western boundary current(Kuroshio) was also observed in 2013. We hypothesize that nutrient availability may have played a major role in regulating the biogeography of N2 fixation.In surface waters, volumetric N2 fixation rate(calculated by nitrogen) ranged between 0.6 and 2.6 nmol/(L·d) and averaged(1.2±0.5) nmol/(L·d), with <10 μm size fraction contributed predominantly(88%±6%) to the total rate between 135°E and 160°E. Depth-integrated N2 fixation rate over the upper 200 m ranged between 150 μmol/(m^2·d)and 480 μmol/(m^2·d)average(225±105) μmol/(m^2·d). N2 fixation can account for 6.2%±3.7% of the depthintegrated primary production, suggesting that N2 fixation is a significant N source sustaining new and export production in the WTNP. The role of N2 fixation in biogeochemical cycling in this climate change-vulnerable region calls for further investigations.
基金the Higher Education Commission Pakistan for funding the lab research under its International Research Support Initiative Program (IRSIP) programthe Department of Environmental Science, Quaid-i-Azam University, Islamabad (especially Environmental Hydro geochemistry Lab)the Environment & Sustainability Institute and Camborne School of Mines, University of Exeter, for technical support in conducting lab analysis
文摘The Paleocene coals of the Salt Range in the Punjab Province of Pakistan have great economic potential;however,their trace element and stable isotopic characteristics have not been studied in detail except for a few sporadic samples.In this study,a total of 59 coal samples of which 14 are obtained from open cast mines have been investigated for elemental composition andδ^(13)C-δ^(15)N isotopic signatures.Average contents of trace elements such as Co,Cr,Cu,Pb,Sr,Th,U,V,and Zn are 7.4,41.7,11.2,12.5,90.2,4.0,1.9,128,and 31.1 mg/kg,respectively.These values,when compared with the World Coal Clarke values,were relatively higher in low-rank coals in comparison with Clarke values for brown coals.Likewise,As(20.4 mg/kg),Co(6.6 mg/kg),Cr(22.4 mg/kg),Cu(^(13).3 mg/kg),Pb(19.2 mg/kg),Sr(^(15)4.7 mg/kg),Th(2.5 mg/kg),V(47.8 mg/kg),and Zn(75.1 mg/kg)were significantly higher in the sub-bituminous to bituminous coals of the Salt Range.Mineralogical analysis,based on X-ray diffraction and energy dispersive X-ray spectroscopy,revealed that the studied samples contain illite,kaolinite calcite,gypsum,pyrite,and quartz.Elemental affinity with organic and inorganic phases of coals calculated by an indirect statistical approach indicated a positive association of ash content with Ag,Al,Co,Cr,Cs,Cu,Mn,P,Rb,Pb,Th,U,and V,suggesting the presence of inorganic components in studied coals.However,As,Fe,Sr,and Zn exhibit negative correlations that imply their association with the organic fraction.Theδ^(13)C andδ^(15)N isotopic range and average−24.94‰to−25.86‰(−25.41‰)and−2.77‰to 3.22‰(0.96‰),respectively,reflecting 3C type modern terrestrial vegetation were common in the palaeomires of studied coal seams.In addition,the trivial variations of 0.92‰and 0.45‰among^(13)C and^(15)N values can be attributed to water level fluctuations and plant assemblies.
基金supported by the National Natural Science Foundation of China (41971104)the Open Foundation of the State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment+1 种基金Chinese Academy of Sciences (CASSKLLQG1817)the Qilian Mountain National Park Research Center (Qinghai)(GKQ2019-01)。
文摘A knowledge of the tree-ring stable nitrogen isotope ratio(δ^(15)N)can deepen our understanding of forest ecosystem dynamics by indicating the long-term availability,cycling and sources of nitrogen(N).However,the radial mobility of N blurs the interannual variations in the long-term N records.Previous studies of the chemical extraction of tree rings before analysis had produced inconsistent results and it is still unclear whether it is necessary to pre-treat wood samples from specific tree species to remove soluble N compounds before determining theδ^(15)N values.We compared the effects of pre-treatment with organic solvents and hot ultrapure water on the N concentration andδ^(15)N of tree rings from endemic Qinghai spruce(Picea crassifolia)growing in the interior of the central Qilian Mountains,China,during the last 60 a.We assessed the effects of different preparation protocols on the removal of the labile N compounds and investigated the need to pre-treat wood samples before determining theδ^(15)N values of tree rings.Increasing trends of the tree-ring N concentration were consistently observed in both the extracted and unextracted wood samples.The total N removed by extraction with organic solvents was about 17.60%,with a significantly higher amount in the sapwood section(P<0.01).Theδ^(15)N values of tree rings decreased consistently from 1960 to 2019 in both the extracted and unextracted wood samples.Extraction with organic solvents increased theδ^(15)N values markedly by about 5.2‰and reduced the variations in theδ^(15)N series.However,extraction with hot ultrapure water had little effect,with only a slight decrease in theδ^(15)N values of about 0.5‰.Our results showed that the radial pattern in the inter-ring movement of N in Qinghai spruce was not minimized by extraction with either organic solvents or hot ultrapure water.It is unnecessary to conduct hot ultrapure water extraction for the wood samples from Qinghai spruce because of its negligible effect on the removal of the labile N.Theδ^(15)N variation trend of tree rings in the unextracted wood samples was not influenced by the heartwood-sapwood transition zone.We suggest that theδ^(15)N values of the unextracted wood samples of the climate-sensitive Qinghai spruce could be used to explore the ecophysiological dynamics while focusing on the long-term variations.
文摘Aims Mycorrhizas(fungal roots)play vital roles in plant nutrient acquisition,performance and productivity in terrestrial ecosystems.Arbuscular mycorrhizas(AM)and ectomycorrhizas(EM)are mostly important since soil nutrients,including NH+4,NO3 and phosphorus,are translocated from mycorrhizal fungi to plants.Individual species,genera and even families of plants could be interconnected by mycorrhizal mycelia to form common mycorrhizal networks(CMNs).The function of CMNs is to provide pathways for movement or transfer of nutrients from one plant to another.In the past four decades,both ^(15)N external labeling or enrichment(usually expressed as atom%)and ^(15)N naturally occurring abundance(d^(15)N,&)techniques have been employed to trace the direction and magnitude of N transfer between plants,with their own advantages and limitations.Important Findings The heavier stable isotope ^(15)N is discriminated against 14N during biochemical,biogeochemical and physiological processes,due to a greater atomic mass.In general,non-N2-fixing plants had greater d^(15)N values than N2-fixing(;0&)ones.Foliar d^(15)N often varied by 5 to 10&in the order:non-mycorrhizas/AMs>EMs>ericoid mycorrhizas.Differences in d^(15)N(&)or ^(15)N(atom%)values could thus provide N transfer information between plants.A range of between 0 to 80%of one-way N transfer had been observed from N2-fixing mycorrhizal to non-N2-fixing mycorrhizal plants,but generally less than or around 10%in the reverse direction.Plant-to-plant N transfer may provide practical implications for plant performance in N-limited habitats.Considering that N translocation or cycling is crucial,and the potential benefits of N transfer are great in both agricultural and natural ecosystems,more research is warranted on either oneway or two-way N transfers mediated by CMNs with different species and under field conditions.
基金supported by the National Natural Science Fund of China(No.51878300)the Natural Science Foundation of Fujian Province of China(No.2019J01052)the Science and Technology Project Foundation of Xiamen City(No.3502Z20203044).
文摘In this study,aluminum-based P-inactivation agent(Al-PIA)was used as a high-efficiency microbial carrier,and the biological Al-PIA(BA-PIA)was prepared by artificial aeration.Laboratory static experiments were conducted to study the effect of BA-PIA on reducing nitrogen and phosphorus contents in water.Physicochemical characterization and isotope tracing method were applied to analyze the removal mechanism of nitrogen and phosphorus.High-throughput techniques were used to analyze the characteristic bacterial genus in the BA-PIA system.The nitrogen and phosphorus removal experiment was conducted for 30 days,and the removal rates of NH_(4)^(+)-N,TN and TP by BA-PIA were 81.87%,66.08%and 87.97%,respectively.The nitrogen removal pathways of BA-PIA were as follows:the nitrification reaction accounted for 59.0%(of which denitrification reaction accounted for 56.4%),microbial assimilation accounted for 18.1%,and the unreacted part accounted for 22.9%.The characteristic bacteria in the BA-PIA system were Streptomyces,Nocardioides,Saccharopolyspora,Nitrosomonas,and Marinobacter.The loading of microorganisms only changed the surface physical properties of Al-PIA(such as specific surface area,pore volume and pore size),without changing its surface chemical properties.The removal mechanism of nitrogen by BA-PIA is the conversion of NH_(4)^(+)-N into NO_(2)^(−)-N and NO_(3)^(−)-N by nitrifying bacteria,which are then reduced to nitrogen-containing gas by aerobic denitrifying bacteria.The phosphorus removal mechanism is that metal compounds(such as Al)on the surface of BA-PIA fix phosphorus through chemisorption processes,such as ligand exchange.Therefore,BA-PIA overcomes the deficiency of Al-PIA with only phosphorus removal ability,and has better application prospects.
文摘Ethylene participates in the regulation of numerous cellular events and biological processes, including wa- ter loss, during leaf and flower petal wilting. The diverse ethylene responses may be regulated via dynamic interplays between protein phosphorylation/dephosphorylation and ubiquitin/26S proteasome-mediated protein degradation and protease cleavage. To address how ethylene alters protein phosphorylation through multi-furcated signaling pathways, we performed a lSN stable isotope labelling-based, differential, and quantitative phosphoproteomics study on air- and ethylene-treated ethylene-insensitive Arabidopsis double loss-of-function mutant ein3-1/eill-1. Among 535 non-redundant phosphopeptides identified, two and four phosphopeptides were up- and downregulated by ethylene, respectively. Ethylene- regulated phosphorylation of aquaporin PIP2;1 is positively correlated with the water flux rate and water loss in leaf. Genetic studies in combination with quantitative proteomics, immunoblot analysis, protoplast swelling/shrinking experiments, and leaf water loss assays on the transgenic plants expressing both the wild-type and S280A/S283A-mutated PIP2;1 in the both Col-O and ein3eill genetic backgrounds suggest that ethylene increases water transport rate in Arabidopsis cells by enhancing S280/S283 phosphorylation at the C terminus of PIP2;1. Unknown kinase and/or phosphatase activities may participate in the initial up- regulation independent of the cellular functions of EIN3/EIL1. This finding contributes to our understanding of ethylene-regulated leaf wilting that is commonly observed during post-harvest storage of plant organs.
基金This work was supported by the Natural Science Foundation of China(31972511)the National Key Research and Development Program of China(No.2018YFD03003082017YFD0300700).
文摘Combined application of biochar with fertilizers has been used to increase soil fertility and crop yield.However,the coupling mechanisms through which biochar improves crop yield at field scale and the time span over which biochar affects carbon and nitrogen transformation and crop yield are still little known.In this study,a long-term field trial(2013-2019)was performed in brown soil planting maize.Six treatments were designed:CK-control;NPK-application of chemical fertilizers;C1PK-low biochar without nitrogen fertilizer;C1NPK,C_(2)NPK and C_(3)NPK-biochar at 1.5,3 and 6 t ha^(−1),respectively,combined with chemical fertilizers.Results showed that theδ^(15)N value in the topsoil of 0-20 cm layer in the C_(3)NPK treat-ment reached a peak of 291‰at the third year(2018),and demonstrated a peak of 402‰in the NPK treatment in the initial isotope trial in 2016.Synchronously,SOC was not affected until the third to fourth year after biochar addition,and resulted in a significant increase in total N of 2.4 kg N ha^(−1) in 2019 in C_(3)NPK treatment.During the entire experiment,the ^(15)N recovery rates of 74-80%were observed highest in the C_(2)NPK and C_(3)NPK treatments,resulting in an annual increase in yields significantly.The lowest subsoilδ^(15)N values ranged from 66‰to 107‰,and the ^(15)N residual rate would take 70 years for a complete decay to 0.001%in the C_(3)NPK.Our findings suggest that biochar compound fertilizers can increase C stability and N retention in soil and improve N uptake by maize,while the loss of N was minimized.Biochars,therefore,may have an important potential for improving the agroecosystem and ecological balance.
基金the Special research fund grant BOF.DCV.2017.0006.01 of Ghent University.
文摘Biochar amendment of soil may ameliorate inherently infertile soils,such as in the typical coconut(Cocos nucifera L.)growth areas along tropical coasts,where,moreover,temporary moisture stress commonly occurs.We conducted a pot experiment to evaluate the effects of biochar soil amendment(1%w/w)produced from Gliricidia sepium stems(BC-Gly)and rice husks(BC-RiH)on the growth of coconut seedlings and on N and P uptake mediated by mycorrhizae under wet or dry conditions in a Sandy Regosol.The pots were divided into root and hyphal zones by a nylon mesh,where 15N labelled N and P nutrients were only provided in the hyphal zone.Under wet conditions,biochar applica-tion did not affect plant growth,while under dry conditions,the BC-Gly increased root and plant growth similar to that under wet conditions.BC-Gly increased the acidic pH of the soil to a neutral level,and the microbial community shifted towards a higher fungal abundance.The P accumulated(Pacc)in roots was higher with BC-Gly and BC-RiH under dry and wet conditions,respectively.Pacc weakly correlated with the abundance of arbuscular mycorrhizal fungi(AMF)in the hyphal zone.With BC-Gly roots showed lower N derived from fertilizer.We conclude that biochar application has no impact on crop growth under wet conditions,while under dry conditions,BC-Gly stimulates crop growth and P uptake,probably through liming induced P availability but also possibly by some enhancement of AMF growth.The shift in the fungal-oriented microbial community and reduced plant fertilizer N uptake suggested that BC-Gly acted as an additional N source.
