Water and nitrogen fertilization are the key factors limiting maize productivity.The genetic basis of interactions between maize genotype,water,and nitrogen is unclear.A recombinant inbred line(RIL)maize population wa...Water and nitrogen fertilization are the key factors limiting maize productivity.The genetic basis of interactions between maize genotype,water,and nitrogen is unclear.A recombinant inbred line(RIL)maize population was evaluated for seven yield and five agronomic traits under four water and nitrogen conditions:water stress and low nitrogen,water stress and high nitrogen,well-watered and low nitrogen,and well-watered and high nitrogen.Respectively eight,six,and six traits varied in response to genotype–water interactions,genotype–nitrogen interactions,and genotype–water–nitrogen interactions.Using a linkage map consisting of 896 single-nucleotide polymorphism markers and multipleenvironmental quantitative-trait locus(QTL)mapping,we identified 31 QTL,including 12 for genotype–water–nitrogen interaction,across the four treatments.A set of 8060 genes were differentially expressed among treatments.Integrating genetic analysis,gene co-expression,and functional annotation revealed two candidate genes controlling genotype–water–nitrogen interactions,affecting both leaf width and grain yield.Genes involved in abscisic acid biosynthesis and bZIP,NAC,and WRKY transcription factors participated in maize response to water and nitrogen conditions.These results represent a step toward understanding the genetic regulatory network of maize that responds to water and nitrogen stress and provide a theoretical basis for the genetic improvement of both water-and nitrogen-use efficiency.展开更多
The interactions of water management and nitrogen fertilizer on nitrogen absorption and utilization were studied in rice with Wuxiangjing9 (japonica). The results showed that the nitrogen uptake and remaining in straw...The interactions of water management and nitrogen fertilizer on nitrogen absorption and utilization were studied in rice with Wuxiangjing9 (japonica). The results showed that the nitrogen uptake and remaining in straw increased and the percentage of nitrogen translocation (PNT) from vegetative organs, nitrogen dry matter production efficiency (NDMPE) and nitrogen grain production efficiency (NGPE) decreased with nitrogen increasing. The nitrogen uptake and NGPE decreased when severe water stressed. However, rice not only decreased the nitrogen uptake but also increased the PNT from vegetative organs, NDMPE and NGPE when mild water stressed. There were obvious interactions between nitrogen fertilizer and water management, such as with water stress increasing the effect of nitrogen on increasing nitrogen uptake was reduced and that on decreasing NDMPE was intensified.展开更多
Knowledge of the interactive effects of water and nitrogen(N)on physio-chemical traits of maize(Zea mays L.)helps to optimize water and N management and improve productivity.A split-plot experiment was conducted with ...Knowledge of the interactive effects of water and nitrogen(N)on physio-chemical traits of maize(Zea mays L.)helps to optimize water and N management and improve productivity.A split-plot experiment was conducted with three soil water conditions(severe drought,moderate drought,and fully water supply referring to 45%-55%,65%-75%,and 85%-95%field capacity,respectively)and four N application rates(N0,N150,N240,and N330 referring to 0,150,240,330 kg N ha^(-1)respectively)under drip fertigation in 2014 and 2015 in the Huang-Huai-Hai Plain of China.The results indicated that drought stress inhibited physiological activity of plants(leaf relative water content,root bleeding sap,and net photosynthetic rate),resulting in low dry matter accumulation after silking,yield,and N uptake,whereas increased WUE and NUE.N application rates over than 150 kg ha^(-1)aggravated the inhibition of physiological activity under severe drought condition,while it was offset under moderate drought condition.High N application rates(N330)still revealed negative effects under moderate drought condition,as it did not consistently enhance plant physiological activity and significantly reduced N uptake as compared to the N240 treatment.With fully water supply,increasing N application rates synergistically enhanced physiological activity,promoted dry matter accumulation after silking,and increased yield,WUE,and N uptake.Although the N240 treatment reduced yield by 5.4%in average,it saved 27.3%N under full water supply condition as compared with N330 treatment.The results indicated that N regulated growth of maize in aspects of physiological traits,dry matter accumulation,and yield as well as water and N use was depended on soil water status.The appropriate N application rates for maize production was 150 kg ha^(-1)under moderate drought or 240 kg ha^(-1)under fully water supply under drip fertigation,and high N supply(>150 kg ha^(-1))should be avoided under severe drought condition.展开更多
When evaluating hyporheic exchange in a flowing stream, it is inappropriate to directly compare stream stage with subsurface hydraulic head (h) to determine direction and magnitude of the gradient between the stream a...When evaluating hyporheic exchange in a flowing stream, it is inappropriate to directly compare stream stage with subsurface hydraulic head (h) to determine direction and magnitude of the gradient between the stream and the subsurface. In the case of moving water, it is invalid to ignore velocity and to assume that stage equals the net downward pressure on the streambed.? The Bernoulli equation describes the distribution of energy within flowing fluids and implies that net pressure decreases as a function of velocity, i.e., the Venturi Effect, which sufficiently reduces the pressure on the streambed to create the appearance of a downward gradient when in fact the gradient may be upward with stream flow drawing water from the subsurface to the surface. A field study correlating the difference between subsurface head and stream stage in a low-gradient stream indicates that the effect is present and significant: shallow subsurface head increases less quickly than stage while deeper subsurface head increases more quickly. These results can substantially improve conceptual models and simulations of hyporheic flow.展开更多
In addition to being used as an energy source,coal also has significant potential for other,more sustainable uses including water treatment.In this study,we present a simple approach to treat water that was produced d...In addition to being used as an energy source,coal also has significant potential for other,more sustainable uses including water treatment.In this study,we present a simple approach to treat water that was produced during oil production and contained a total dissolved solids(TDS)content of over 150 g/L using Powder River Basin(PRB)coal.PRB coal used as packing material in a flow-through column effectively removed 60%–80%of the cations and anions simultaneously.Additionally,71%–92%of the total organic carbon in the produced water was removed as was all of the total suspended solids.The removal mechanisms of both cations and anions were investigated.Cations were removed by ion exchange with protons from oxygen-containing functional groups such as carboxylic and phenolic hydroxyl groups.Anions,mainly Cl−1,appeared to be removed through either the formation of resonance structures as a result of delocalization of electrons within coal molecules or through ion–πinteractions.We propose that coal is a“pseudo-amphoteric”exchange material that can remove cations and anions simultaneously by exchanging ions with both ionized and non-ionized acids that are ubiquitous in coal structure or resonance effect.展开更多
基于检索1950-2016年发表在中国知网、Google Scholar、Web of Science等数据库的文章,筛选出关于我国退耕还草工程与土壤有机碳的文献123篇(126个研究地点)。基于筛选文献,提取了农田和恢复草地的土壤有机碳含量、土壤有效养分含量、...基于检索1950-2016年发表在中国知网、Google Scholar、Web of Science等数据库的文章,筛选出关于我国退耕还草工程与土壤有机碳的文献123篇(126个研究地点)。基于筛选文献,提取了农田和恢复草地的土壤有机碳含量、土壤有效养分含量、恢复时间和气候等数据735条,旨在探究我国退耕还草工程对土壤有机碳含量的影响及其主导因素。结果表明:1)农田恢复为草地后,土壤有机碳含量呈先下降后上升趋势(时间拐点约为第6年),整体上退耕还草工程使土壤有机碳含量提高了19.8%。2)土壤有机碳的正响应随土壤深度增加而减弱,且深度超过1 m时其正响应不明显。3)土壤有效氮是影响土壤有机碳恢复的主要因素,而土壤有效磷和植物功能群对其影响不大。4)沿着增加的水分梯度,土壤有机碳的恢复效果由负变正,转变阈值为25.15 (干旱指数)。总体而言,我国退耕还草工程对土壤有机碳含量的影响为正效应,此效应受环境梯度和恢复时间的共同影响。本研究能够为我国土地利用变化背景下土壤碳库管理的相关决策提供科学依据。展开更多
Experimental study and theoretical analysis show that the critical value of relative wave height (H / d)b given by Goda and the critical wave steepness (H / L)b given by Michell and Miche can be adopted as the spillin...Experimental study and theoretical analysis show that the critical value of relative wave height (H / d)b given by Goda and the critical wave steepness (H / L)b given by Michell and Miche can be adopted as the spilling breaking indices of regular waves. According to the same principle, a systematic theoretical analysis and experiment of irregular wave have been done by the authors in order to solve the breaking problem of irregular waves. It is indicated that the authors' method for determining wave breaking of regular waves can also be used for irregular waves.展开更多
明确不同水氮互作对强筋优质小麦师栾02-1产量和加工品质的影响,为强筋小麦生产中如何通过合理灌溉和优化氮肥施用量来实现协同提高籽粒产量和加工品质的目标提供理论依据。2017-2020年,大田条件下设置浇水次数和施氮量二因子裂区试验,...明确不同水氮互作对强筋优质小麦师栾02-1产量和加工品质的影响,为强筋小麦生产中如何通过合理灌溉和优化氮肥施用量来实现协同提高籽粒产量和加工品质的目标提供理论依据。2017-2020年,大田条件下设置浇水次数和施氮量二因子裂区试验,主区为浇水次数,设春浇一水(W1,拔节水)和春浇两水(W2,拔节水+开花水);副区为氮肥施用量,设N0、N1、N2、N3、N4和N5(0、60、120、180、240和300 kg hm^(-2))6个水平。结果表明,施氮量0~300 kg hm^(-2)时,不同降水年型春浇一水、春浇两水小麦产量随施氮量的增加均先增加后减少,产量最高值对应的施氮量均为240 kg hm^(-2)。施氮量120~300 kg hm^(-2)时,春浇两水处理产量显著高于春浇一水处理。水氮互作对小麦单位面积收获穗数的影响最大,其次是千粒重,对穗粒数的影响最小。施氮量0~300 kg hm^(-2)时,2017-2018年度(丰水年型),春浇两水小麦湿面筋含量、沉降值、吸水率、面团稳定时间、拉伸能量、最大拉伸阻力平均值均高于春浇一水,而2018-2019、2019-2020年度(干旱年型)则相反:春浇一水高于春浇两水。不同降水年型春浇一水、春浇两水小麦湿面筋含量和沉降值随施氮量的增加先增加后减少或逐渐增加,二者最大值对应的施氮量为240 kg hm^(-2)或300 kg hm^(-2);稳定时间、拉伸能量和最大拉伸阻力随施氮量的增加均先增加后减少,施氮量240 kg hm^(-2)时达到最大值。不同降水年型强筋优质小麦师栾02-1生育期春浇两水、施氮量240 kg hm^(-2)时,籽粒产量和加工品质表现最佳。展开更多
针对干旱绿洲灌区水资源匮乏、玉米生产化肥投入量大等问题,在水氮减量条件下,探讨增大密度对玉米干物质积累、籽粒产量和产量构成的影响,以期为建立水氮减量玉米稳产高效技术体系提供依据。20202021年,在地方习惯灌水减量20%(3240 m^(3...针对干旱绿洲灌区水资源匮乏、玉米生产化肥投入量大等问题,在水氮减量条件下,探讨增大密度对玉米干物质积累、籽粒产量和产量构成的影响,以期为建立水氮减量玉米稳产高效技术体系提供依据。20202021年,在地方习惯灌水减量20%(3240 m^(3)hm^(-2),W1)、习惯灌水(4050 m3hm^(-2),W2)和减量施氮25%(270 kg hm^(-2),N1)、习惯施氮(360 kg hm^(-2),N2)条件下,研究密度从7.50万株hm^(-2)(低,D1)提高30%(中,D2)、60%(高,D3)时,玉米干物质积累及产量的响应特征。研究表明,水、氮减量均显著降低玉米籽粒产量,增密30%可补偿水氮同时减量导致的产量降低效应;施氮量不变降低灌水量时,增密可显著提高产量。2个试验年度内,W1较W2、N1较N2产量分别降低3.0%、12.9%,D2、D3较D1产量分别高12.9%、9.2%;W1N1D1较W2N2D1处理减产12.3%,W1N1D2与W2N2D1处理产量差异不显著。增密30%能够补偿水氮减量减产的主要原因是提高了灌浆初期到成熟期干物质的累积量和成穗数,W1N1D2与W2N2D1相比,灌浆初期到成熟期干物质积累量提高5.8%,Vmax(最大干物质积累速率)、Vmean(平均干物质积累速率)、Tm(最大干物质积累速率出现时间)、HI(收获指数)差异均不显著,穗数增加24.7%,但穗粒数、千粒重分别降低19.3%和14.8%。W1N2D2较W2N2D1处理增产13.9%。当施氮量不变时,减水增密稳产的主要原因是提高了干物质积累量、Vmean、HI和穗数,W1N2D2与W2N2D1相比,穗数、干物质积累、Vmean和HI分别提高24.8%、10.2%、8.4%和4.7%,千粒重差异不显著。因此,本试验水氮同步减量条件下增密30%,是绿洲灌区玉米水氮节约稳产高产的可行措施;在施氮量保持不变但灌水量减少20%时,密度提高30%是玉米节水增产的有效措施。展开更多
基金the National Key Research and Development Program of China(2021YFD1200700)the National Natural Science Foundation of China(32272076)+1 种基金the Hainan Provincial Science and Technology Plan Sanya Yazhou Bay Science and Technology City Joint Project(320LH011)the Inner Mongolia Foundation for the Conversion of Scientific and Technological Achievements(2021CG0026).
文摘Water and nitrogen fertilization are the key factors limiting maize productivity.The genetic basis of interactions between maize genotype,water,and nitrogen is unclear.A recombinant inbred line(RIL)maize population was evaluated for seven yield and five agronomic traits under four water and nitrogen conditions:water stress and low nitrogen,water stress and high nitrogen,well-watered and low nitrogen,and well-watered and high nitrogen.Respectively eight,six,and six traits varied in response to genotype–water interactions,genotype–nitrogen interactions,and genotype–water–nitrogen interactions.Using a linkage map consisting of 896 single-nucleotide polymorphism markers and multipleenvironmental quantitative-trait locus(QTL)mapping,we identified 31 QTL,including 12 for genotype–water–nitrogen interaction,across the four treatments.A set of 8060 genes were differentially expressed among treatments.Integrating genetic analysis,gene co-expression,and functional annotation revealed two candidate genes controlling genotype–water–nitrogen interactions,affecting both leaf width and grain yield.Genes involved in abscisic acid biosynthesis and bZIP,NAC,and WRKY transcription factors participated in maize response to water and nitrogen conditions.These results represent a step toward understanding the genetic regulatory network of maize that responds to water and nitrogen stress and provide a theoretical basis for the genetic improvement of both water-and nitrogen-use efficiency.
基金supported by the National Natural Science Foundation of China(30030090) Jiangsu Key Project of Science and Technology(BE2001331).
文摘The interactions of water management and nitrogen fertilizer on nitrogen absorption and utilization were studied in rice with Wuxiangjing9 (japonica). The results showed that the nitrogen uptake and remaining in straw increased and the percentage of nitrogen translocation (PNT) from vegetative organs, nitrogen dry matter production efficiency (NDMPE) and nitrogen grain production efficiency (NGPE) decreased with nitrogen increasing. The nitrogen uptake and NGPE decreased when severe water stressed. However, rice not only decreased the nitrogen uptake but also increased the PNT from vegetative organs, NDMPE and NGPE when mild water stressed. There were obvious interactions between nitrogen fertilizer and water management, such as with water stress increasing the effect of nitrogen on increasing nitrogen uptake was reduced and that on decreasing NDMPE was intensified.
基金This research was supported by the National Key Research and Development Program of China(No.2017YFD0301106)the National Natural Science Foundation of China(Nos.31871553 and 31601258).
文摘Knowledge of the interactive effects of water and nitrogen(N)on physio-chemical traits of maize(Zea mays L.)helps to optimize water and N management and improve productivity.A split-plot experiment was conducted with three soil water conditions(severe drought,moderate drought,and fully water supply referring to 45%-55%,65%-75%,and 85%-95%field capacity,respectively)and four N application rates(N0,N150,N240,and N330 referring to 0,150,240,330 kg N ha^(-1)respectively)under drip fertigation in 2014 and 2015 in the Huang-Huai-Hai Plain of China.The results indicated that drought stress inhibited physiological activity of plants(leaf relative water content,root bleeding sap,and net photosynthetic rate),resulting in low dry matter accumulation after silking,yield,and N uptake,whereas increased WUE and NUE.N application rates over than 150 kg ha^(-1)aggravated the inhibition of physiological activity under severe drought condition,while it was offset under moderate drought condition.High N application rates(N330)still revealed negative effects under moderate drought condition,as it did not consistently enhance plant physiological activity and significantly reduced N uptake as compared to the N240 treatment.With fully water supply,increasing N application rates synergistically enhanced physiological activity,promoted dry matter accumulation after silking,and increased yield,WUE,and N uptake.Although the N240 treatment reduced yield by 5.4%in average,it saved 27.3%N under full water supply condition as compared with N330 treatment.The results indicated that N regulated growth of maize in aspects of physiological traits,dry matter accumulation,and yield as well as water and N use was depended on soil water status.The appropriate N application rates for maize production was 150 kg ha^(-1)under moderate drought or 240 kg ha^(-1)under fully water supply under drip fertigation,and high N supply(>150 kg ha^(-1))should be avoided under severe drought condition.
文摘When evaluating hyporheic exchange in a flowing stream, it is inappropriate to directly compare stream stage with subsurface hydraulic head (h) to determine direction and magnitude of the gradient between the stream and the subsurface. In the case of moving water, it is invalid to ignore velocity and to assume that stage equals the net downward pressure on the streambed.? The Bernoulli equation describes the distribution of energy within flowing fluids and implies that net pressure decreases as a function of velocity, i.e., the Venturi Effect, which sufficiently reduces the pressure on the streambed to create the appearance of a downward gradient when in fact the gradient may be upward with stream flow drawing water from the subsurface to the surface. A field study correlating the difference between subsurface head and stream stage in a low-gradient stream indicates that the effect is present and significant: shallow subsurface head increases less quickly than stage while deeper subsurface head increases more quickly. These results can substantially improve conceptual models and simulations of hyporheic flow.
基金This work was supported by USGS Wyoming Program.
文摘In addition to being used as an energy source,coal also has significant potential for other,more sustainable uses including water treatment.In this study,we present a simple approach to treat water that was produced during oil production and contained a total dissolved solids(TDS)content of over 150 g/L using Powder River Basin(PRB)coal.PRB coal used as packing material in a flow-through column effectively removed 60%–80%of the cations and anions simultaneously.Additionally,71%–92%of the total organic carbon in the produced water was removed as was all of the total suspended solids.The removal mechanisms of both cations and anions were investigated.Cations were removed by ion exchange with protons from oxygen-containing functional groups such as carboxylic and phenolic hydroxyl groups.Anions,mainly Cl−1,appeared to be removed through either the formation of resonance structures as a result of delocalization of electrons within coal molecules or through ion–πinteractions.We propose that coal is a“pseudo-amphoteric”exchange material that can remove cations and anions simultaneously by exchanging ions with both ionized and non-ionized acids that are ubiquitous in coal structure or resonance effect.
文摘Experimental study and theoretical analysis show that the critical value of relative wave height (H / d)b given by Goda and the critical wave steepness (H / L)b given by Michell and Miche can be adopted as the spilling breaking indices of regular waves. According to the same principle, a systematic theoretical analysis and experiment of irregular wave have been done by the authors in order to solve the breaking problem of irregular waves. It is indicated that the authors' method for determining wave breaking of regular waves can also be used for irregular waves.
文摘明确不同水氮互作对强筋优质小麦师栾02-1产量和加工品质的影响,为强筋小麦生产中如何通过合理灌溉和优化氮肥施用量来实现协同提高籽粒产量和加工品质的目标提供理论依据。2017-2020年,大田条件下设置浇水次数和施氮量二因子裂区试验,主区为浇水次数,设春浇一水(W1,拔节水)和春浇两水(W2,拔节水+开花水);副区为氮肥施用量,设N0、N1、N2、N3、N4和N5(0、60、120、180、240和300 kg hm^(-2))6个水平。结果表明,施氮量0~300 kg hm^(-2)时,不同降水年型春浇一水、春浇两水小麦产量随施氮量的增加均先增加后减少,产量最高值对应的施氮量均为240 kg hm^(-2)。施氮量120~300 kg hm^(-2)时,春浇两水处理产量显著高于春浇一水处理。水氮互作对小麦单位面积收获穗数的影响最大,其次是千粒重,对穗粒数的影响最小。施氮量0~300 kg hm^(-2)时,2017-2018年度(丰水年型),春浇两水小麦湿面筋含量、沉降值、吸水率、面团稳定时间、拉伸能量、最大拉伸阻力平均值均高于春浇一水,而2018-2019、2019-2020年度(干旱年型)则相反:春浇一水高于春浇两水。不同降水年型春浇一水、春浇两水小麦湿面筋含量和沉降值随施氮量的增加先增加后减少或逐渐增加,二者最大值对应的施氮量为240 kg hm^(-2)或300 kg hm^(-2);稳定时间、拉伸能量和最大拉伸阻力随施氮量的增加均先增加后减少,施氮量240 kg hm^(-2)时达到最大值。不同降水年型强筋优质小麦师栾02-1生育期春浇两水、施氮量240 kg hm^(-2)时,籽粒产量和加工品质表现最佳。
文摘针对干旱绿洲灌区水资源匮乏、玉米生产化肥投入量大等问题,在水氮减量条件下,探讨增大密度对玉米干物质积累、籽粒产量和产量构成的影响,以期为建立水氮减量玉米稳产高效技术体系提供依据。20202021年,在地方习惯灌水减量20%(3240 m^(3)hm^(-2),W1)、习惯灌水(4050 m3hm^(-2),W2)和减量施氮25%(270 kg hm^(-2),N1)、习惯施氮(360 kg hm^(-2),N2)条件下,研究密度从7.50万株hm^(-2)(低,D1)提高30%(中,D2)、60%(高,D3)时,玉米干物质积累及产量的响应特征。研究表明,水、氮减量均显著降低玉米籽粒产量,增密30%可补偿水氮同时减量导致的产量降低效应;施氮量不变降低灌水量时,增密可显著提高产量。2个试验年度内,W1较W2、N1较N2产量分别降低3.0%、12.9%,D2、D3较D1产量分别高12.9%、9.2%;W1N1D1较W2N2D1处理减产12.3%,W1N1D2与W2N2D1处理产量差异不显著。增密30%能够补偿水氮减量减产的主要原因是提高了灌浆初期到成熟期干物质的累积量和成穗数,W1N1D2与W2N2D1相比,灌浆初期到成熟期干物质积累量提高5.8%,Vmax(最大干物质积累速率)、Vmean(平均干物质积累速率)、Tm(最大干物质积累速率出现时间)、HI(收获指数)差异均不显著,穗数增加24.7%,但穗粒数、千粒重分别降低19.3%和14.8%。W1N2D2较W2N2D1处理增产13.9%。当施氮量不变时,减水增密稳产的主要原因是提高了干物质积累量、Vmean、HI和穗数,W1N2D2与W2N2D1相比,穗数、干物质积累、Vmean和HI分别提高24.8%、10.2%、8.4%和4.7%,千粒重差异不显著。因此,本试验水氮同步减量条件下增密30%,是绿洲灌区玉米水氮节约稳产高产的可行措施;在施氮量保持不变但灌水量减少20%时,密度提高30%是玉米节水增产的有效措施。
