Effects of dense planting patterns on photosynthetic traits of different vertical layers and yield of wheat under different nitrogen rates

A two-year field experiment was conducted to measure the effects of densification methods on photosynthesis and yield of densely planted wheat.Inter-plant and inter-row distances were used to define ratefixed pattern(RR)and row-fixed pattern(RS)density treatments.Meanwhile,four nitrogen(N)rates(0,144,192,and 240 kg N ha-1,termed N0,N144,N192,and N240)were applied with three densities(225,292.5,and 360×10^(4)plants ha^(-1),termed D225,D292.5,and D360).The wheat canopy was clipped into three equal vertical layers(top,middle,and bottom layers),and their chlorophyll density(Ch D)and photosynthetically active radiation interception(FIPAR)were measured.Results showed that the response of Ch D and FIPAR to N rate,density,and pattern varied with different layers.N rate,density,and pattern had significant interaction effects on Ch D.The maximum values of whole-canopy Ch D in the two seasons appeared in N240 combined with D292.5 and D360 under RR,respectively.Across two growing seasons,FIPAR values of RR were higher than those of RS by 29.37%for the top layer and 5.68%for the middle layer,while lower than those of RS by 20.62%for the bottom layer on average.With a low N supply(N0),grain yield was not significantly affected by density for both patterns.At N240,increasing density significantly increased yield under RR,but D360 of RS significantly decreased yield by 3.72%and 9.00%versus D225 in two seasons,respectively.With an appropriate and sufficient N application,RR increased the yield of densely planted wheat more than RS.Additionally,the maximum yield in two seasons appeared in the combination of D360 with N144 or N192 rather than of D225 with N240 under both patterns,suggesting that dense planting combined with an appropriate N-reduction application is feasible to increase photosynthesis capacity and yield.

Effect of drip irrigation method, nitrogen source, and flushing schedule on emitter clogging

Field experiments were carried out at the National Research Center farm, Nubaria area, Behura Governorate, Egypt, to study the effect of nitrogen source, flushing schedule and irrigation method on emitter clogging. Peanut Giza 5 variety (Arachishy pogaea L.) was planted in sandy soil during two successive growing seasons (2010-2011) in the 1st week of May and harvested after 130 days. Treatments used are: 1) two irrigation methods: surface drip irrigation and sub-surface drip irrigation (SDI;SSDI), 2) nitrogen source (NS):NH4NO3, (NH4)2SO4 and Ca(NO3)2 (NS1, NS2 and NS3) and 3) flushing number (FL) 0, 1 and 4 (FL1, FL2;FL3). The experiments design was split-split plot and three replicates were used. Data obtained were subjected to statistical analysis. The main effects of treatments used on clogging per cent could be written the following ascending orders: SDI 3 2 1, NS1 2 3. Concerning the 1st interaction the following ascending orders denote their effects on clogging percent: SDI × FL3 2 1, SDI × NS1 2 3, SSDI × FL3 2 1, SSDI × NS1 2 3, FL1 × NS1 1 × NS2 1 × NS3, FL2 × NS1 2 × NS2 2 × NS3 and FL3 × NS1 3 × NS2 3 × NS3. The differences between any two treatments and/or any two interactions in clogging percent were significant at the 5% level. The effect of the 2nd interaction on clogging percent was significant at the 5% level. The maximum value of clogging (20.18%) and the lowest one (3.9%) were archived in the interactions: SSDI × FL1 × NS3 and SDI × FL3 × NS1, respectively.

Effects of Tillage Methods on Soil Organic Carbon and Total Nitrogen Content in the Loess Plateau

In order to determine whether long-term no-tillage operation in the loess plateau threatens soil fertility and crop yield,a suitable high-yield and efficient tillage technology system was established.In the Changwu loess plateau agri-Gecological experiment station of the Northwest A&F University of Changwu County,Shaanxi Province,the no-tillage experimental field for three consecutive years was selected.In September 2015,no-tillage,tillage,and rotary tillage were carried out before winter wheat was sowed.After the harvest of winter wheat in2016,soil organic carbon,total nitrogen and wheat yield in 0-30 cm soil layers under different tillage methods were analyzed.The results showed that the soil organic carbon and total nitrogen contents in the 0-30 cm soil layer decreased along the profile under the three tillage methods.In this study,the soil organic carbon and total nitrogen content in the 0-10 cm soil layer under different tillage methods were no-tillage>rotary tillage>tillage,the actual yield of winter yield in one hectare was tillage>rotary tillage>no-tillage,and there was significant difference in the actual yield of winter wheat only between the no-tillage and tillage.

Leaching and Transformation of Nitrogen Fertilizers in Soil After Application of N with Irrigation: A Soil Column Method

A soil column method was used to compare the effect of drip fertigation (the application of fertilizer through drip irrigation systems, DFI) on the leaching loss and transformation of urea-N in soil with that of surface fertilization combined with flood irrigation (SFI), and to study the leaching loss and transformation of three kinds of nitrogen fertilizers (nitrate fertilizer, ammonium fertilizer, and urea fertilizer) in two contrasting soils after the fertigation. In comparison to SFI, DFI decreased leaching loss of urea-N from the soil and increased the mineral N (NH4+-N + NO3- -N) in the soil. The N leached from a clay loam soil ranged from 5.7% to 9.6% of the total N added as fertilizer, whereas for a sandy loam soil they ranged between 16.2% and 30.4%. Leaching losses of mineral N were higher when nitrate fertilizer was used compared to urea or ammonium fertilizer. Compared to the control (without urea addition), on the first day when soils were fertigated with urea, there were increases in NH4+-N in the soils. This confirmed the rapid hydrolysis of urea in soil during fertigation. NH4+-N in soils reached a peak about 5 days after fertigation, and due to nitrification it began to decrease at day 10. After applying NH4+-N fertilizer and urea and during the incubation period, the mineral nitrogen in the soil decreased. This may be related to the occurrence of NH4+-N fixation or volatilization in the soil during the fertigation process.

Deconvolution Method for Determination of the Nitrogen Content in Cellulose Carbamates

Cellulose carbamates (CC) were synthesized with microcrystalline cellulose as raw materials. The Fourier transform infrared spectra of CC with different nitrogen content were recorded. The accurate results of the nitrogen content for CC can be obtained by using the deconvolution method when the nitrogen content is less than 3.5%. The relationship between the nitrogen content and the absorption intensity ratio of the corresponding separated absorption peaks in FTIR spectra has been expressed bg an equation precisely.

Modified Conway Method for soil available nitrogen testing

The ideal reducing reagent in testing available nitrogen of soil by Conway Methodis Devard‘s alloy.The optimum ratio of soil:Devard’s alloy:1.0N NaOH solution is 5.0g:0.2g:5ml.When reaction goes on at 30℃ for 4 hours,the rate of soil NO3-N reduction is about 90%,and the recovery rate of soil NH4-N is about 95%.Some organic nitrogen can be measured at thesame time.This method is defined as the Modified Conway Method and the soil N-min is r=0.982（n=10）.In predicting soil nitrogen supplying power,the Modified Conway Method takesonly 1/6 of time needed by Conway Method.The Modified Conway Method can also be used forthe measure of soil N-min.

Synthesis of large diamond crystals containing high-nitrogen concentration at high pressure and high temperature using Ni-based solvent by temperature gradient method

This paper reprots that with Ni-based catalyst/solvent and with a dopant of NAN3, large green single crystal diamonds with perfect shape are successfully synthesized by temperature gradient method under high pressure and high temperature in a China-type cubic anvil high-pressure apparatus （SPD-6 × 1200）, and the highest nitrogen concentration reaches approximately 121-1257 ppm calculated by infrared absorption spectra. The synthesis conditions are about 5.5 CPa and 1240-1300 ℃. The growth behaviour of diamond with high-nitrogen concentration is investigated in detail. The results show that, with increasing the content of NaN3 added in synthesis system, the width of synthesis temperature region for growth high-quality diamonds becomes narrower, and the morphology of diamond crystal is changed from cube-octahedral to octahedral at same temperature and pressure, the crystal growth rate is slowed down, nevertheless, the nitrogen concentration doped in synthetic diamond increases.

A NEW FACILE METHOD FOR THE SYNTHESIS OF AZACROWN ETHERS BY USING BENZYLSULFONAMIDE AS A SOURCE OF NITROGEN

Benzylsulfonamide was used as a source of nitrogen in the syn- thesis of azacrown ethers,and the cyclic intermediates were easily deben- zylsulfonylated by treating with CaF_2/H_2SO_4 to afford the azacrown ethers.

Recent progress in research and design concepts for the characterization,testing,and photocatalysts for nitrogen reduction reaction

The reduction of molecular nitrogen(N_(2))to ammonia(NH_(3))under mild conditions is one of the most promising studies in the energy field due to the important role of NH_(3)in modern industry,production,and life.The photocatalytic reduction of N_(2)is expected to achieve clean and sustainable NH_(3)production by using clean solar energy.To date,the new photocatalysts for photocatalytic reduction of N_(2)to NH_(3)at room temperature and atmospheric pressure have not been fully developed.The major challenge is to achieve high light-absorption efficiency,conversion efficiency,and stability of photocatalysts.Herein,the methods for measuring produced NH_(3)are compared,and the problems related to possible NH_(3)pollution in photocatalytic systems are mentioned to provide accurate ideas for measuring photocatalytic efficiency.The recent progress of nitrogen reduction reaction(NRR)photocatalysts at ambient temperature and pressure is summarized by introducing charge transfer,migration,and separation in photocatalytic NRR,which provides a guidance for the selection of future photocatalyst.More importantly,we introduce the latest research strategies of photocatalysts in detail,which can guide the preparation and design of photocatalysts with high NRR activity.

惰气熔融-红外吸收/热导法同时测定无烟煤中氮和氢

首次使用惰气熔融-红外吸收/热导法实现无烟煤中氮、氢元素的同时、快速、准确测定.探究分析条件,发现当称样量为0.0300 g,分析功率为5500 W,氮元素的积分延迟时间为15 s,集成时间为55 s,氢元素的积分延迟时间为5 s,集成时间为85 s,且使用石墨套埚时,氮氢元素的释放最完全、合理.方法中氮、氢校准曲线的相关系数分别为0.9949、0.9940,检出限分别为0.321%、0.189%,定量限分别为0.326%、0.194%,精密度分别为3.60%、0.63%,满足线性关系及方法要求.惰气熔融-红外吸收/热导法重复性好、高效便捷、操作和维护简单,可用于无烟煤中氮、氢元素的定量检测.

中国农业废弃物源活性氮排放特征、驱动因素及差异性分析

旨在研究农业废弃物源活性氮排放规律和监测活性氮污染,进而为减少活性氮排放量和提高氮污染治理公平提供理论依据,研究首先采用排放因子法测算了1990—2019年全国农业废弃物源活性氮排放量,并分析确定了我国(除港澳台之外)31个省级行政区域的活性氮排放特征。然后利用LMDI模型和集中指数法分别研究农业废弃物源活性氮排放变化量的驱动因素和活性氮排放量的地区差异性。结果发现,1990—2019年,全国农业废弃物源活性氮排放量在1996年达到峰值,整体呈现“M”型变化趋势;全国范围内人均活性氮排放强度呈现以胡焕庸线为界的西北低密度—东南高密度的格局。基于农产品前端消费及其农业废弃物末端处置2个维度来考察活性氮的排放特征,从农产品消费端来看,消费肉类农产品生产活性氮排放量占比(36.75%)最高,其中,牛羊肉类农产品占比高达22%;从农业废弃物末端处置来看,处置畜禽粪尿产生的活性氮占比较高,且对畜禽粪尿和秸秆而言直接排放与燃烧还田均是活性氮排放量较高的2种处置方式。国家层面农业废弃物源活性氮排放量的驱动因素为经济发展效应,而省级层面农业废弃物源活性氮排放变化量的主要驱动因素为经济发展效应、购买能力效应和消费结构效应。活性氮排放总量、人均活性氮和地均活性氮排放量均是农业经济强省较高,这些省份承担了更多的氮污染环境压力。

BER-BCO耦合工艺净化模拟微污染河水及除磷机理研究

针对传统生物膜法对微污染河水脱氮除磷效率不佳的问题,设计了电极生物膜耦合生物接触氧化(BER-BCO)装置,采用单因素敏感性分析方法评估了不同碳源、电流密度、水力停留时间、填料填充比对工艺脱氮除磷效果的影响,并通过红外光谱表征阳极附近沉淀物表面特征官能团,探究系统除磷机理。结果表明,在使用乙酸钠为碳源、电流密度为0.09 mA/cm^(2)、水力停留时间控制为24 h、填料比为40%的条件下,BER-BCO系统的脱氮除磷效能得到了显著优化;NH+4-N、TN、TP的去除率分别达到了83.10%、56.46%、97.93%;最终出水除TN外均优于《地表水环境质量标准》(GB 3838-2002)中Ⅳ类水质标准;红外光谱分析显示阳极附近形成的含磷沉淀物中含有Fe-O键、P-O键、Fe-OH键,表明铁阳极具有高效除磷的特性。

盾尾刷更换时液氮冻结温度场及冻结参数影响的数值模拟分析

为合理确定高水压下液氮冻结止水更换盾尾刷的冻结设计参数及掌握温度场变化规律,结合某过江通道长距离盾构掘进过程中盾尾刷更换时的液氮冻结止水工程,利用ADINA大型有限元分析软件建立液氮冻结止水及盾尾刷更换数值模型,模拟温度-时间变化曲线与现场实测数据对比,验证模型的合理性,并对土层、去路液氮温度、冻结管长度、冻结管间距、冻结方式进行敏感性因素分析。结果表明:1)冻结效果随土层的不同而发生改变,在卵石层、砾砂层、粉细砂层3种土层中,粉细砂层的冻结效果最差,卵石层最好;2)在有限的冻结时间内,去路液氮温度的不同,只影响土体从开始冻结至越过0℃完成相变这期间的降温速度,不影响完成冻结以后的土体降温速率;3)冻结管长度对土层冻结的影响较小,可以采用较短的冻结管,以降低施工成本和液氮消耗量,但不能过短,应保证其纵向有足够的支撑范围,经计算分析,当冻结管长度为1.52 m时,能在轴面处满足2.0 m的冻结壁厚度要求;4)冻结管间距对冻结效果影响大,冻结管越密,冻结速度越快,效果越好;5)在相同条件下,双环预埋冻结管液氮冻结效果优于管片上直接打孔液氮冻结。

隔两年深松配合条旋耕显著提升冬小麦的氮素吸收利用效率和产量

【目的】探究耕作方式对小麦氮代谢和氮素利用效率的影响,为小麦高产高效生产提供理论依据。【方法】长期定位试验位于山东省济宁市兖州区小孟镇,始于2007年,供试冬小麦品种为‘济麦22’。设置常年翻耕(PT)、常年旋耕(RT)、常年条旋耕(ST)和隔两年深松+条旋耕(STS)4个处理。2023年在小麦开花期和成熟期采集植株样品,测定各器官含氮量。在开花后0~28天,每隔7天取一次样,测定旗叶硝酸还原酶(NR)、谷氨酰胺合成酶(GS)活性以及游离氨基酸和可溶性蛋白含量。于成熟期,调查产量及其构成因素,并计算氮素利用效率。【结果】与PT、RT和ST处理相比,STS处理提高了小麦旗叶硝酸还原酶活性、谷氨酰胺合成酶活性、游离氨基酸与可溶性蛋白含量,增加了开花期植株各部位和成熟期籽粒的氮素积累量、花前氮素转运量和转运率以及花后氮素吸收量对籽粒的贡献率,提高了氮素吸收效率、籽粒氮素利用效率、氮素收获指数和氮肥偏生产力。其中,成熟期籽粒氮素积累量增加了8.53%~30.15%,籽粒氮分配比例增加了4.59%~14.06%,千粒重和产量分别提高了4.20%~9.96%和7.83%~18.39%,氮肥偏生产力提高了7.85%~18.40%。【结论】隔两年深松+条旋耕(STS)的耕作方式可提高小麦氮代谢相关酶活性,增强氮素的吸收和同化能力,提高氮素利用效率,同时增加小麦籽粒产量。

氮肥运筹与硅锌肥配施对虾稻1号产量和品质的影响

为探讨优质食味籼稻虾稻1号产量和品质协同提升栽培技术,在施氮量180 kg/hm^(2)水平下,研究3种基肥∶分蘖肥∶穗肥运筹比例(7∶3∶0、5∶3∶2和3∶3∶4,分别记作N_(7+3+0)、N_(5+3+2)和N_(3+3+4))并配施硅锌肥处理对虾稻1号产量和品质的影响。结果表明,不同处理下虾稻1号产量整体表现为N_(7+3+0)<N_(5+3+2)≈N_(3+3+4)。提高氮肥在穗肥中的比例,虾稻1号糙米率、精米率和整精米率呈先增加后降低趋势,而胶稠度和蛋白质含量呈上升趋势。其中,氮肥运筹对整精米率的影响达到显著水平,对蛋白质含量的影响达到极显著水平。相同氮肥运筹方式下,配施硅肥或硅锌肥均表现出一定的增产效应,但对稻米品质指标的影响均未达到显著水平。综上所述,N_(5+3+2)运筹方式可实现虾稻1号产量与品质的协同提升,而配施硅锌肥有助于其产量进一步提升。

冻结方式对黑斑蛙后腿肌肉持水性及肌原纤维蛋白结构特性的影响

本研究采用-20℃冰柜冻结、-50℃冰柜冻结、-50℃液氮冻结、-80℃液氮冻结处理黑斑蛙后腿,探究不同冻结方式及冻结温度对黑斑蛙后腿肌肉持水性及肌原纤维蛋白结构的影响。结果表明:-20℃冰柜冻结、-50℃冰柜冻结、-50℃液氮冻结、-80℃液氮冻结组通过最大冰晶生成带(-1~-5℃)的时间分别为91.5、57.0、1.5、0.5 min。相比两组冰柜冻结组,两组液氮冻结组的解冻损失率降低,不易流动水含量升高,自由水含量下降;相比新鲜样品,冷冻后黑斑蛙后腿的肌原纤维持水性、蛋白溶解度、总巯基含量、内源荧光强度显著下降,蛋白粒径、表面疏水性、无规卷曲相对含量呈现升高趋势。其中-50℃液氮冻结组的肌原纤维持水性、蛋白溶解度、总巯基含量、内源荧光强度分别下降了8.10%、9.57%、10.50%、67.36%,体积平均粒径、表面疏水性、无规卷曲相对含量分别增加了100.05%、82.24%、13.65%,变化幅度显著低于其他实验组(P<0.05)。-80℃液氮冻结组黑斑蛙后腿肌原纤维蛋白变性程度显著低于-20℃冰柜冻结组,但高于-50℃液氮冻结组(P<0.05)。扫描电子显微镜观察结果显示,-50℃冰柜冻结和-50℃液氮冻结组肌纤维排列较为紧密规则,-80℃液氮冻结的黑斑蛙肌纤维排列规整但有轻微裂隙,-20℃冰柜冻结组肌纤维出现明显破裂。综上,液氮冻结可减缓黑斑蛙后腿肌肉冷冻过程中水分迁移,有效抑制黑斑蛙肌原纤维蛋白的冷冻变性,其中-50℃液氮冻结效果优于-80℃液氮冻结。

甘肃高寒阴湿区播种方式和氮肥施用量对猫尾草种质生产性能的影响

采用裂区试验设计,通过研究甘肃高寒阴湿区4个氮肥施用量(A1:施纯氮量0 kg/hm^(2),A2:施纯氮量90 kg/hm^(2),A3:施纯氮量180 kg/hm^(2),A4:施纯氮量360 kg/hm^(2))和3种播种方式(B1:条播,B2:撒播,B3:点播)对4个猫尾草种质(C1:新品系,C2:‘川西’,C3:‘岷山’,C4:‘克劳沃1号’)生产性能的影响,以筛选出最佳氮肥施用量、最佳播种方式和最佳猫尾草种质。结果表明,从单因素看,4个氮肥施用量间,A4的平均生产性能最好;3种播种方式间,B3的平均生产性能最好;4个猫尾草种质中,C1的平均生产性能最好。从二因素交互作用看,氮肥施用量×猫尾草种质交互作用间,A4C3的平均生产性能最好;播种方式×猫尾草种质交互作用间,B3C1的平均生产性能最好;氮肥施用量×播种方式交互作用间,A4B3的平均生产性能最好。从三因素交互作用看,C1在A2B3处理下生产性能最好;C2和C4在A4B3处理下生产性能最好;C3在A4B2处理下生产性能最好。综上,新品系的最佳氮肥施用量为90 kg/hm^(2),最佳播种方式为点播;‘川西’和‘克劳沃1号’的最佳氮肥施用量为360 kg/hm^(2),最佳播种方式为点播;‘岷山’的最佳氮肥施用量为360 kg/hm^(2),最佳播种方式为撒播。

秸秆不同还田模式下磷钾释放特征及其对玉米产量的影响

连续两年(2021—2022年)在吉林省四平市设置田间定位试验,采用尼龙网袋法测定覆盖(SM)和翻压(SB)两种秸秆还田方式和不施氮肥(N0)、180 kg·hm^(-2)(N180)两种施氮水平下秸秆磷、钾释放率,旨在明确黑土区玉米秸秆磷、钾释放规律对还田方式和氮肥管理的响应及其对玉米产量的影响。结果表明,还田方式与施氮显著影响秸秆磷、钾释放,SB处理秸秆磷两年累积释放率平均为69.7%,显著高于SM处理的54.5%;与N0处理相比,施氮处理秸秆磷释放率提高了12.3%。SB处理秸秆钾两年累积释放率平均为95.6%,显著高于SM处理的94.2%;而施氮对秸秆钾累积释放影响同样显著,肥料氮素投入使秸秆钾累积释放率提高1.1%。通过对秸秆磷、钾替代潜力的估算,认为秸秆磷对磷肥(P2O5)替代潜力较低,为9.1 kg·hm^(-2);但秸秆钾对钾肥(K_(2)O)替代潜力较高,为141.0 kg·hm^(-2)。两年间还田方式对玉米产量无明显影响,但玉米穗粒数存在一定差异。SB处理玉米穗粒数为430粒·穗^(-1),显著高于SM处理的409粒·穗^(-1)。而施氮则明显促进了产量的形成,提高了玉米产量,与N0处理相比,两年玉米产量平均增加7707 kg·hm^(-2)。通过结合秸秆磷、钾养分释放综合分析,认为在黑土区充足氮素供应条件下以翻压方式进行秸秆还田,秸秆释放的磷、钾养分有利于穗粒的形成,从而保障产量稳定。