水稻秸秆用量对淹水培养土壤表层溶液理化性质的影响

采用模拟培养的方法,研究水稻秸秆用量对淹水培养土壤表层溶液理化性质的影响。试验根据秸秆还田量设0g·盆-1、100g·盆-1、200g·盆-1和300g·盆-14个处理,每盆装土15kg,施尿素2.8g以调节系统碳氮比,分别测定培养液的电导率、pH、全氮、全磷、全钾等指标。研究结果表明,各处理表层溶液电导率在培养初期呈上升趋势,第36d达到最大值,分别为960μs·cm-1、1150μs·cm-1、1467μs·cm-1和1620μs·cm-1,随后略有降低,到培养结束时分别为683μs·cm-1、910μs·cm-1、1083μs·cm-1和1277μs·cm-1。pH值在培养的前3d呈缓慢下降趋势,与秸秆用量呈负相关;从第4d开始pH迅速升高,16d后达到相对稳定状态,到培养结束时变化不大。施加的尿素导致各处理培养液中全氮在20d内保持较高浓度,随后全氮浓度迅速下降,到第76d,下降趋势减缓;施加秸秆对全氮浓度影响较小,施加秸秆能够提高全磷含量。秸秆中钾释放迅速,培养1d后,溶液全钾含量达到较高浓度,分别为6.87mg·L-1、36.10mg·L-1、60.27mg·L-1、114.23mg·L-1,在整个培养期全钾浓度变化不大。淹水培养条件下施加秸秆能够增加培养液中电导率、全磷及全钾浓度,与秸秆用量呈正比,但对pH、全氮影响较小。从养分流失角度考虑,控制田面养分流失主要时期为水稻秸秆还田后30d内。     

Rapid method for quantitative analysis of the aroma impact compound, 2-acetyl-1-pyrroline, in fragrant rice using automated headspace gas chromatography

A rapid method employing static headspace gas chromatography (HS-GC) has been developed and validated for quantitative analysis of the impact aroma compound, 2-acetyl-1-pyrroline (2AP), in grains of fragrant rice. This developed method excludes wet extraction, and the rice headspace volatiles are brought directly and automatically to GC analysis. The conditions of the static HS autosampler were optimized to achieve high recovery and sensitivity. The most effective amount of rice sample used was 1 g, which provided 51% recovery and a linear multiple headspace extraction (MHE) plot of the peak area of 2AP. The sensitivity of the method was enhanced by utilizing a megabore fused silica capillary column in conjunction with a nitrogen-phosphorus detector (NPD). Method validations performed for both static HS-GC-FID and HS-GC-NPD demonstrated linear calibration ranges of 20-10 000 (r(2) = 0.9997) and 5-8000 (r(2) = 0.9998) ng of 2AP/g of rice sample, respectively. The limits of detection for both systems were 20 and 5 ng of 2AP, and the limits of quantitation were 0.30 and 0.01 g of brown rice sample, respectively. Reproducibility calculated as intraday and interday coefficients of variation were 3.25% RSD (n = 15) and 3.92% RSD (n = 35), respectively, for SHS-GC-FID and 1.87% RSD (n = 15) and 2.85% RSD (n = 35), respectively, for SHS-GC-NPD. The method was found to be effective when applied to the evaluation of aroma quality, based on 2AP concentrations, of some fragrant rice samples.     

γ-氨基丁酸对番茄嫁接苗耐盐性的生理调控效应

[目的]γ-氨基丁酸(GABA)可增强作物品质和抗逆性,但其效果是否受植株根系耐盐性的影响尚不明确。因此,研究添加外源GABA对不同耐盐性番茄嫁接苗的生理调节机制及生长的影响,为小分子氨基酸在蔬菜生产中的应用提供理论依据。[方法]以耐盐性较强的砧用番茄‘OZ-006’为砧木、对盐分较敏感的‘中杂9号’为接穗形成的嫁接苗(RS)为材料,以‘中杂9号’自嫁接苗(SS)为对照材料,进行无土营养液栽培试验。以Hoagland营养液为基础,以调节NaCl浓度至175 mmol/L形成的盐胁迫条件作为对照(CK),在CK基础上设置添加5 mmol/L GABA处理(+G)。从处理后3天起,测定了幼苗生长、Na⁺积累、氨基酸含量及活性氧代谢指标。[结果]随着NaCl胁迫时间的延长,SS和RS幼苗均显著受到盐胁迫伤害,但RS幼苗盐害指数及Na+含量显著低于SS幼苗,其生长速率、叶绿素含量及氨基酸含量显著高于SS幼苗,其O2·-和MDA含量显著低于SS幼苗,表现为耐盐性显著高于SS幼苗。添加外源GABA后,SS和RS幼苗的鲜重、生长速率、叶绿素及氨基酸(GABA、谷氨酸和脯氨酸)含量、抗氧化酶(SOD、POD和CAT)活性均显著提高,根系和叶片内Na+含量、O2·-产生速率及MDA含量均显著降低,且SS幼苗耐盐性提高的效果大于RS幼苗。[结论]盐胁迫显著影响番茄幼苗的生长,尤其对耐盐性弱的品种生长抑制更加显著。γ-氨基丁酸(GABA)可有效提高番茄嫁接苗的耐盐性,主要原因在于GABA为幼苗提供了氮素营养,促进了盐胁迫下植物的生长和叶绿素的合成,同时GABA诱导细胞内多种氨基酸含量上升,叶片渗透调节能力增强,从而抑制了Na⁺过量积累,缓解了细胞内活性氧积累带来的膜伤害。此外,GABA添加对耐盐性弱的番茄嫁接苗耐盐性的提升效果比对耐盐性强的番茄嫁接苗更加明显。因此,在盐胁迫条件下,施用外源小分子氨基酸(如GABA)可能是提高作物耐盐能力的有效措施。     

氮锌肥配施对南方香粳稻产量和品质的影响

【目的】研究氮锌肥配施对南方香粳稻产量和外观加工品质、蒸煮食味品质、香气的影响,为南方香粳稻的调优栽培提供科学依据。【方法】田间试验于2020和2021年在扬州大学试验基地进行,供试粳稻品种为宁香粳9号和南粳46。在施锌(+Zn)和不施锌(Zn0)条件下,分别设3个施氮水平：0 (N0)、180 kg/hm²(N180)、270 kg/hm²(N270),共6个处理。于收获期,测定产量和产量构成因素,分析籽粒加工外观、食味和香气品质。【结果】提高氮肥用量可显著增加香粳稻产量,而施用锌肥对香粳稻产量无显著影响,+ZnN270处理宁香粳9号和南粳46产量均最高,分别达10.48 t/hm²和10.40 t/hm²;相同氮肥用量下,增施锌肥对产量没有显著影响。宁香粳9号和南粳46的最佳稻米加工和外观品质均以+ZnN270处理最优。在相同氮肥用量下,施用锌肥改善了香粳稻的加工和外观品质。与N0处理相比,在N180和N270处理下两品种的直链淀粉含量下降了8.44%～13.16%,蛋白质含量增加了9.79%～...     

头季稻氮肥运筹对再生稻干物质积累、产量及氮素利用率的影响

为探讨头季稻不同肥料运筹方式对再生稻产量和氮素利用率的影响,以杂交稻组合"Ⅱ优航2号"为材料,在头季施氮量225.00kg·hm-2的基础上,研究了不同基蘖穗肥氮素配比[3种基蘖肥与穗肥配比分别为8:2(N1)、7:3(N2)、6:4(N3)]头季稻-再生季稻氮素累积量、干物质生产、产量及氮素利用率的特性。结果表明:与N1、N2相比,头季成熟期N3处理氮素累积量分别增加9.26%、3.54%,头季齐穗期～头季成熟期N3处理氮素转移量分别增加21.47%、6.76%,整个生育期N3处理干物质净积累总量分别增加5.10%、4.78%。N3处理头季产量最高,达12431kg·hm-2,极显著高于N1、N2处理;氮肥利用率达46.44%,比N1、N2处理提高14.81%、5.43%;氮肥农学利用率达20.66kg·kg-1,比N1、N2处理提高14.97%、12.34%。研究结果还表明,头季不同基蘖穗肥氮素配比对再生稻再生季的影响不显著。     

稻田处理养殖场粪便的氮磷动态效应与污染风险研究

对盆栽水稻施以不同水平的猪粪和牛粪两种有机肥料,结合其本身对氮磷的吸收利用状况及养分在土壤和水体环境下的分解释放规律,研究了水稻对有机粪肥的消纳吸收能力。结果表明,水稻可以有效地处理猪粪和牛粪;综合生态效益与经济效益,在处理猪粪时,P5水平（猪粪处理量120000kg·hm^-2,折合纯氮量l103．52kg·hm^-2）下的处理效果最好,处理牛粪时,C6水平（牛粪处理量300000kg·hm^-2,折合纯氮量3224．5kg·hm^-2）下的处理效果最好,施肥量低于此的植株生长缓慢,高于此则植株的增产效应不明显,并且容易出现受害症状,而有机肥对环境的二次污染风险会加大。     

Tolerance of rice plants to trace metals

Abstract

The tolerance of rice (Oryza sativa L. C.V. Earlirose) to various trace metal excesses was tested to determine if high levels of the trace metals found in some field‐grown plants were at toxicity levels. In one experiment, levels of 2200 μg Zn/g dry weight, 44 μg Cu/g dry weight, 4400 μg Mn/g dry weight, and 32 μg Pb/g dry weight in shoots of young plants had no adverse effects on vegetative yields. A level of 3160μgZn/ g dry weight decreased yields about 40% (P = . 05). In another test 51 μg Cu/g dry weight or 94 μg Pb/g dry weight did not decrease vegetative yields. Boron supplied at 10^‐3 MH₃BO₃ not only caused no toxicity but resulted in only 144 μg B/g dry weight in shoots. Root levels of Zn were about equal to those in shoots; Mn levels were lower in roots than in shoots (1/4 to 1/10); B levels were generally low in both shoots and roots with roots 1/10 that of shoots; Cu levels were higher in roots than in shoots. Rice was tolerant of a high level of Cr. The tolerance of rice to high levels of some trace metals in these experiments may be related to high P levels in plants.     

Identification and quantitation of the rice aroma compound, 2-acetyl-1-pyrroline,in bread flowers (Vallaris glabra Ktze)

The aroma impact compound, 2-acetyl-1-pyrroline (2AP), has been identified for the first time in headspace of fresh bread flowers (Vallaris glabra Ktze) in which volatile components were extracted by solid-phase microextraction (SPME) at room temperature prior to analysis by gas chromatography-mass spectrometry. A total of 50 volatiles were detected. Among these, 23 volatiles were identified, predominantly in a group of terpenes. More volatiles were found in the extract of fresh bread flowers obtained by continuous steam distillation and solvent extraction (SDS). Of the 40 volatiles identified, the additional components were mainly straight-chain saturated hydrocarbons. 2AP was found in the extracts obtained by both SPME (0.37%) and SDS (2.71% relative proportion). Quantitative analyses of 2AP in bread flowers and other plant materials were performed by solvent extraction employing acidic solutions and capillary GC with flame ionization detection. The highest concentration of 2AP was found in dried flowers of V. glabra at 26.1 mg/kg. By comparison with other plant sources, fresh leaves of Pandanus amaryllifolius Roxb contain 2AP at 10.3 mg/kg and Thai fragrant rice, Khao Dawk Mali 105, at 3.0 mg/kg.     

不同氮效率基因型冬小麦物质生产对CO2浓度升高的响应研究

采用开顶式气室,以不同氮效率基因型冬小麦品种"小偃6号"(氮低效)和"小偃22号"(氮高效)为供试材料,通过盆栽方法,研究不同施氮水平下大气CO2浓度倍增对冬小麦叶面积、株高、生物量和产量的影响。结果表明,在CO2浓度倍增条件下,施氮后氮高效小麦基因型"小偃22号"穗长、株高显著高于氮低效小麦"小偃6号",但叶面积、茎长则相反。施氮水平、基因型和大气CO2浓度水平均不同程度地影响冬小麦生物量、产量及产量构成。同一施氮条件下,大气CO2浓度倍增使两种氮效率基因型冬小麦产量均显著增加,但增加量不尽一致:N1[0.15 g(N).kg-1(土)]处理时,氮低效"小偃6号"和氮高效"小偃22号"产量分别增加90.5%和52.9%,N2[0.30 g(N).kg-1(土)]处理时分别增加73.9%和93.6%。同一施氮条件下,大气CO2浓度倍增使两种氮效率基因型冬小麦地上部、根系、总生物量、每盆穗数、穗粒数和产量也均显著增加。从不同施氮水平看,大气CO2浓度倍增下(750μmol.mol–1)两种氮效率基因型冬小麦地上部、总生物量、穗粒数和产量均表现为N2>N1>N0。说明在该试验条件下,CO2浓度倍增及氮肥投入对作物生长及产量形成存在显著正交互效应。因此,在未来大气CO2浓度增加条件下,增加氮肥投入应有利于促进作物对大气CO2浓度升高的正效应,增加冬小麦的物质生产及提高产量。     

秸秆还田对稻田渗漏液DOC含量及土壤Cd活度的影响

通过盆栽试验,研究了秸秆还田对稻田渗漏液DOC含量及重金属污染土壤Cd溶出的影响。结果表明,秸秆还田增加了稻田渗漏液的DOC含量,提高了土壤Cd的活度。稻田渗漏水DOC的浓度随秸秆还田量的增加而增大。秸秆还田增加了Cd随稻田渗漏水的流失,使得稻田土壤Cd全量、有效态Cd量均随秸秆还田量的增加而降低,部分处理降低幅度达显著水平。本试验条件下由于较多的秸秆还田影响了水稻生长,使水稻植株Cd浓度、累积量均随秸秆还田量的增加呈先上升后下降的趋势。秸秆还田0.5%处理的水稻植株Cd浓度、累积量最高,分别为45.10mg·kg-1、1858.1μg·pot-1。     

分蘖期水稻地上部和空气间的NOX (NO,NO2 ) 交换作用

采用密闭箱法结合42 C型 NO-NO2-NOX 分析仪的快速线检测系统,在气候箱严密控光（L1）和室内自然光暗处理（L2）条件下,研究了分蘖期水稻地上部和空气间的NOX（NO, NO2 ）交换作用,结果表明: 1）试验用水稻品种具有较强的NO挥发能力,在L1、L2条件下水稻NO平均挥发速率 [按鲜质量（g, FW）计算] 分别达到0.0188、0.0239 g/（g·h）,并在环境空气NO浓度达100 g/m3条件下水稻也能净排放NO;2）水稻能吸收空气NO2,L1、L2条件下水稻NO2平均净吸收速率为0.00084、0.00165 g/（g·h）;3）施氮能增强水稻NO挥发,在气候箱严密控光（L1）条件下,短期内（1～2 d）施氮在日间 6:00～10:00 弱光时段和 10:00～14:00强光时段有刺激水稻NOX （NO, NO2 ）挥发的效应, 但在14:00～18:00 时段,持续强光能削弱施氮对水稻NO挥发的刺激作用而增强水稻对NO2吸收。4）室内自然弱光条件下（L2）,施氮能提高日间水稻的NO净挥发速率,水稻NO2净吸收速率随着有光时间的延长而上升。夜间暗处理条件下,施氮对促进水稻NO的挥发无明显作用,水稻NO2吸收速率下降。试验结果显示,水稻地上部从空气中净吸收NO2的平均速率远低于NO净挥发速率,分蘖期水稻地上部分与空气间的NOX （NO, NO2 ）交换作用主要表现为NO的净挥发,相当于净损失纯N 10.95～12.5 g/（hm2 ·d）。     

Determination of multiresidues in rapeseed, rapeseed oil, and rapeseed meal by acetonitrile extraction, low-temperature cleanup, and detection by liquid chromatography with tandem mass spectrometry

A multiresidue method for determining pesticides in rapeseed, rapeseed oil, and rapeseed meal by use of liquid chromatography-tandem mass spectrometry is developed. Samples were extracted with acetonitrile or acidified acetonitrile and cleaned up by a 12 h freezing step. The recovery data were obtained by spiking blank samples at three concentration levels. The recoveries of 27 selected pesticides in rapeseed, rapeseed oil, and rapeseed meal were in the range of 70-118%, at the concentration level of 10 μg kg(-1), with intraday and interday precisions of lower than 22 and 27%, respectively. Linearity was studied between 2 and 500 μg L(-1) with determination coefficients (R(2)) of higher than 0.98 for all compounds in the three matrices. The limits of quantitation (LOQs) of pesticides in rapeseed, rapeseed oil, and rapeseed meal ranged from 0.3 to 18 μg kg(-1). The n-octanol-water partition coefficient showed more influence than water solubility in extracting pesticides by acetonitrile from matrices of high fat content. This method was successfully applied for routine analysis in commercial products.     

Influence of soil pH and application of zinc on the yield and uptake of selected nutrient elements by rice

Abstract

Rice grown on a recently water‐leveled Crowley silt loam that contained less than 1.8 μg g^‐1 of 0.1 N HCl‐extractable Zn with pH levels ranging from 6.8 to 7.7, responded to Zn application. Each kg ha of applied Zn as Zn chelate, 14.2 % Zn, resulted in increases of +673, +477, and +2026 kg rice ha^‐1 at pH 6.8, 7.3, and 7.7, respectively. There was a critically low concentration of Zn in rice plants at the midtillering, first joint, and panicle differentiation stages of plant development when no Zn was applied. A yield response to applied Zn was obtained when the concentration of Zn in rice tissue was less than 15 μg g^‐1.

Application of Zn resulted in a significant increase in the uptake of N by rice plants at each of the three stages of plant development. Application of Zn also resulted in relatively large and significant increases in the uptake of Zn from the soil irrespective of soil pH. The uptake of Zn by rice plants at each of the growth stages showed a two‐ to three‐fold increase following Zn application when soil pH was 6.8 and 7.3. Also, the uptake of Zn by rice plants following Zn application showed a four‐fold increase at midtillering, a five‐fold increase at first joint, and a six‐fold increase at panicle differentiation, respectively, when soil pH was 7.7.     

猪粪沼液施用对稻麦轮作系统土壤氧化亚氮排放的影响

以典型的猪粪尿发酵沼液为对象,探讨了沼液施入量和管理方式对以中国东部稻麦轮作农田系统土壤N2O排放规律和排放量的影响。研究结果表明,与化学氮肥相比,沼液施用未影响稻麦轮作系统土壤N2O排放的季节变化规律,但影响其排放量的大小。稻季100%施用沼液的处理（N100%DPS）其累积排放量为0.71kg·hm-（22008年）和1.38kg·hm-（22009年）,显著高于100%施用化肥的处理（N100%Ure）a,即0.68kg·hm-2和1.06kg·hm-2。麦季N100%DPS处理N2O的累积排放量分别为6.56kg·hm-（22008年）和5.05kg·hm-2（2009年）,与N100%Urea处理（2008年：5.89kg·hm-2;2009年：3.93kg·hm-2）无显著差异,但均显著高于稻季各处理。随着沼液替代化学肥料用量的降低,稻田N2O排放量呈降低趋势,而沼液一次性施入和分次施入对稻田N2O排放的季节动态和累积排放量均无显著影响;但沼液不同的管理方式对麦季累积N2O排放量更为复杂。稻、麦两季N100%DPS处理中N2O排放系数（f）均最大,分别达到0.3%和1.6%,但沼液分次施入和一次性施入的处理间f值均无显著差异。     

Synthesis of a combinatorial library of amides and its evaluation against the fall armyworm, Spodoptera frugiperda

The fall armyworm Spodoptera frugiperda is a polyphagous pest that causes important damage in different regions of America and mainly affects corn crops in both tropical and subtropical areas. Currently, control relies on both transgenic plants and/or chemical pesticides. In this work we describe the preparation of an indexed combinatorial library of amides and its toxic effect by contact against S. frugiperda . (E)-1-(1-Piperidinyl)-3-[4-(trifluoromethoxy)phenyl]-2-propen-1-one was the most active compound with an LD(50) = 0.793 μg mg(-1) of larva. This amide was also evaluated by ingestion and at the lowest concentration (1 mg kg(-1)) achieved 83.3% mortality.     

等氮配施有机肥对喀斯特峰丛洼地农田作物产量与养分平衡的影响

基于自2006年在广西喀斯特峰丛洼地区开展的长期玉米/大豆套作定位施肥试验,选择2010—2014年监测数据,探讨等氮量投入条件下,不同比例有机肥替代无机氮肥对喀斯特峰丛洼地玉米/大豆套作系统作物产量及土壤养分的影响,为喀斯特峰丛洼地农田作物高效施肥及提高土壤肥力提供理论依据。试验选取4个处理:对照(不施肥,CK)、平衡施用化肥(NPK)、有机粪肥替代30%化肥氮(C7M3,按氮素计算,不足30%的PK用无机肥补充,肥料总量与NPK处理相同,有机粪肥为牛粪,下同)、有机粪肥替代60%化肥氮(C4M6,按氮素计算,不足60%的PK用无机肥补充),每个处理4次重复。于2010年、2012年、2014年大豆收获后采集土壤样品,测定土壤养分状况。结果表明:1)施肥处理土壤有机质、全氮、速效磷及速效钾含量均高于CK处理,其中C4M6处理有机质含量显著高于NPK处理(P0.05),全氮、速效磷和速效钾含量随着有机粪肥施用量的增加而增加。2)长期不同施肥处理玉米和大豆产量分别是不施肥处理的4.15~4.36倍、2.47~2.58倍。不同施肥处理的增产效果为C4M6NPKC7M3,但施肥处理间差异不显著(P0.05)。3)长期不施肥CK处理玉米产量随着试验年限推移呈下降趋势,降幅为5.45 g·m~(-2)·a~(-1),大豆产量却表现出增加趋势,增幅为1.50 g·m~(-2)·a~(-1)。长期施肥处理中,玉米和大豆产量总体呈增加趋势。4)施肥处理中,玉米季表现为钾素亏缺(NPK处理除外),大豆季表现为氮素亏缺。综合两季作物,只有C4M6钾素表现亏缺,亏缺量为7.9 kg·hm~(-2)。磷素在各施肥处理中盈余量较大,分别为81.2 kg·hm~(-2)(NPK)、83.4 kg·hm~(-2)(C7M3)和74.8 kg·hm~(-2)(C4M6)。综上,在喀斯特峰丛洼地玉米/大豆套作制度下,基于作物产量及土壤养分表观平衡特征提出有机粪肥可以代替部分化肥施用,在玉米季适当"减氮、稳磷和增钾",大豆季"稳氮、减磷和减钾"的施肥措施。     

保水缓释肥对盐胁迫下水稻生长和光合特性的调控

为了探讨保水缓释肥对作物生长的调控,以"盐稻12号"为材料,研究了不同配比(1%、2%和4%)的盐碱地保水缓释肥(ZL 2012 1 0400570.0)对盐胁迫20、40、80 d水稻幼苗植株形态、根系发育、干重、叶绿素含量、气体交换参数和水分利用效率的影响。结果表明:无论是低盐还是高盐处理下,随着肥料施用配比的增加,植株长势逐渐增强,总根长、根体积、根表面积、根尖数、植株干重均显著上升,尤其在4%肥料施用下这些促进效果尤为明显;随着肥料施用配比的增加,叶片叶绿素含量、气体交换各参数、水分利用效率等均逐渐上升,而气孔限制值显著下降。综上所述,该盐碱地保水缓释肥明显增强水稻幼苗的耐盐性,主要与其能促进盐胁迫下根系生长,提高叶绿素含量,改善气孔限制,促进植株的光合作用并提高水分利用效率有关。     

协调水稻产量和品质的植株临界氮浓度的确定

根据植株氮营养状况指导优质米生产具有重要意义。试验以五优稻4号为供试材料,以密度为主区（密度分别为每平方米18穴和25穴）,氮量为副区（氮量分别为0、75、105、135 kg hm?2）,测定水稻植株全氮、籽粒无机氮含量、水稻产量和品质等指标,以期为实现水稻丰产优质提供理论依据。结果表明:施氮量和水稻产量呈2次曲线关系,最高产量施氮量为113 ~ 119 kg hm?2,经济合理施氮量为110 ~ 116 kg hm?2;随着施氮量增加,各个时期水稻植株含氮量,收获期籽粒铵态氮和硝态氮含量显著提高,N105处理与N0处理间上述指标差异均显著（P < 0.05）,而 N105和N135处理间只有籽粒无机氮含量差异显著;施氮后籽粒蛋白质含量有增加趋势,随着施氮量增加稻米食味值下降,N135处理食味降低超过10%（P < 0.05）,其他处理间差异不显著。密度增加,水稻氮素积累量增加,产量提高了11.4%;稀植有利于提高地上部含氮量、籽粒铵态氮和硝态氮含量;稀植出米率提高了4.77个百分点（P < 0.05）,食味值有降低趋势。根据肥料效应函数以及施氮量和植株含氮量关系函数,拔节期和抽穗期,D1密度下植株临界氮浓度分别为15.26 ~ 16.18 g kg?1和22.65 ~ 25.98 g kg?1,D2密度下对应值分别为11.71 ~ 12.94 g kg?1和20.73 ~ 23.24 g kg?1。上述结果表明,合理密植有利于水稻高产,氮量过高不利于水稻高产和优质。在水稻丰产和优质的情况下,氮肥用量在91 ~ 105 kg hm?2比较合适,抽穗期叶片含氮量24.82 ~ 25.98 g kg?1（D1）和22.18 ~ 23.24 g kg?1（D2）可以作为协同实现水稻丰产优质的诊断指标。     

环境内分泌干扰物辛基酚、壬基酚及短链壬基酚聚氧乙烯醚残留同步检测方法

建立了环境内分泌干扰物辛基酚、壬基酚及短链壬基酚聚氧乙烯醚降解产物的高效液相色谱串联质谱分析方法。选择易受环境污染的玉米、白菜等农产品及目标物可能迁移到环境中的食品包装材料为研究对象,经过液液萃取、浓缩,乙腈甲苯（3：1）溶液溶解,经ENVITMCarblI／PSA氨基固相萃取柱净化,甲醇一二氯甲烷（4：3）溶液为洗脱液。采用Agilent ZORBAX RX-C18柱,以甲醇：10mmol·L^-1乙酸铵（9：1）为流动相,梯度洗脱分离后,在LC—MS／MS多反应监测模式下正负离子同时扫描进行定性与定量分析。结果表明,该方法对辛基酚、壬基酚、壬基酚一氧乙烯醚和壬基酚二氧乙烯醚的检出限分别为O．03、0.6、1．6、0．03μg·kg^-1,在不同基质中添加浓度为0．5-5μg·kg^-1的四种物质平均回收率在62％～113％之间。对实际样品进行检测时,在蔬菜和粮食作物及其包装材料中分别检测到不同含量的上述物质,表明该方法准确、快速、灵敏度高,可用于农产品和食品包装材料中该类物质的监控。