密度调控对女贞人工林土壤铵态氮和硝态氮季节变化的影响

以江苏扬州市江都区7年生女贞人工林为对象,研究密度调控对其土壤铵态氮（NH4＋-N）和硝态氮（NO3--N）含量剖面分布特征及季节变化的影响。结果表明：不同调控密度下女贞人工林土壤NH4＋-N和NO3--N含量均随着土层深度的增加而逐渐降低,且表现出明显的季节变化;3种密度调控下土壤NH4＋-N 含量均是秋冬两季较高,春季最低,夏季又有明显回升,且3种密度中的2275株/hm2下NH4＋-N含量在4个季节均高于另外2种密度;土壤NO3--N 季节变化与NH4＋-N大体一致,在春季含量最低,但不同密度间变化趋势差异较大;土温、含水量及有机质均与土壤NH4＋-N和NO3--N含量存在显著的相关关系（p＜0.05）,且在夏季均达到极显著相关（p＜0.01）。     

NO对氮胁迫棉花幼苗根系形态的调控效应

以‘农大棉8号’为试验材料,在水培缺氮的情况下,利用一氧化氮(Nitric oxide,NO)的供体硝普钠(Sodi-um nitroprusside,SNP)处理棉花幼苗,研究了外源NO对氮素胁迫条件下棉花幼苗根系形态的调控效应。结果表明:外源NO能够增加氮素胁迫下棉花根长、根表面积、根体积、主根直径和根干重。低浓度的NO(SNP浓度50～100μmol/L)能显著提高根表面积9.39%、根体积10.78%、主根直径8.63%、根系干重39.2%;高浓度NO对氮素胁迫缓解效应较弱。因此,在本试验条件下,低浓度的NO(SNP浓度50～100μmol/L)表现对氮素胁迫下棉花根系生长具有良好促进效应,可能利于增强棉花的抗逆性。     

加味半夏白术天麻汤对痰浊上扰型偏头痛患者的疗效及内皮素-1及一氧化氮水平的影响

目的 观察加味半夏白术天麻汤对痰浊上扰型偏头痛的临床疗效及对内皮素-1和一氧化氮水平的影响。方法 90例痰浊上扰型偏头痛患者随机分为观察组（45例）和对照组（45例）,观察组给予加味半夏白术天麻汤,对照组给予盐酸氟桂利嗪,监测两组偏头痛患者治疗前后头痛发作频次、头痛持续时间、疼痛程度及内皮素-1和一氧化氮水平,疗程6周后统计2组患者的临床疗效及相关指标的差异。结果 观察组总有效率高于对照组（P<0.05）,观察组和对照组治疗后两组患者的内皮素-1水平均较前有所下降（P<0.05）,一氧化氮水平均较前有所升高（P<0.05）。观察组患者内皮素-1及一氧化氮水平较对照组改善明显（P<0.05）。结论 加味半夏白术天麻汤辨证治疗痰浊上扰型偏头痛治疗有效,可能通过影响内皮素-1和一氧化氮水平起作用。     

Afforestation of semi-arid shrubland reduces biogenic NO emission from soil

Nitric oxide (NO) plays a central role in the formation of tropospheric ozone, hydroxyl radicals, as well as nitrous and nitric acids. There are, however, large uncertainties around estimates of global NO emissions due to the paucity of data. In particular, there is little information on the rate of NO emission and its sensitivity to processes such as land use changes in dry environments. Here we report on a two-year study on the influence of afforestation on soil NO fluxes in the semi-arid afforestation system in Southern Israel (Yatir forest, mean annual precipitation ∼280 mm). Laboratory incubations were carried out under seasonally defined conditions of soil moisture and temperature using soils sampled in different seasons from the native shrubland (taken both under shrub canopy and in the inter-shrub areas), and from the adjacent ∼2800 ha, 40-year-old pine afforestation site. Combining laboratory results with field measurements of soil moisture and temperature, we up-scaled soil-atmosphere NO fluxes to the ecosystem level. The different microsites differed in their annual mean NO release rates (0.04, 0.14 and 0.03 mg m⁻² d⁻¹ for the shrubland under and between shrubs and for the forest, respectively), and exhibited high inter-seasonal variability in NO emission rates (ranging from zero up to 0.25 mg m⁻² d⁻¹ in the wet and dry-rewetting seasons, respectively), as well as in temperature responses. Up-scaling results to annual and ecosystem scales indicated that afforestation of the semi-arid shrubland could reduce soil NO emission by up to 65%.     

Effect of improved fallow on crop productivity, soil fertility and climate-forcing gas emissions in semi-arid conditions

The impacts of fallow on soil fertility, crop production and climate-forcing gas emissions were determined in two contrasting legumes, Gliricidia sepium and Acacia colei, in comparison with traditional unamended fallow and continuous cultivation systems. After 2 years, the amount of foliar material produced did not differ between the two improved fallow species; however, grain yield was significantly elevated by 55% in the first and second cropping season after G. sepium compared with traditional fallow. By contrast, relative to the unamended fallow, a drop in grain yield was observed in the first cropping season after A. colei, followed by no improvement in the second. G. sepium had higher foliar N, K and Mg, while A. colei had lower foliar N but higher lignin and polyphenols. In the third year after fallow improvement, a simulated rainfall experiment was performed on soils to compare efflux of N₂O and CO₂. Improved fallow effects on soil nutrient composition and microbial activity were demonstrated through elevated N₂O and CO₂ efflux from soils in G. sepium fallows compared with other treatments. N₂O emissions were around six times higher from this nitrogen-fixing soil treatment, evolving 69.9 ngN₂O–N g⁻¹soil h⁻¹ after a simulated rainfall event, compared with only 8.5 and 4.8 ngN₂O–N g⁻¹soil h⁻¹ from soil under traditional fallow and continuous cultivation, respectively. The findings indicate that selection of improved fallows for short-term fertility enhancement has implications for regional N₂O emissions for dry land regions.     

硝酸钙对荔枝花粉萌发和花粉管生长的影响

采用不同浓度的硝酸钙及EGTA处理对‘妃子笑’荔枝的花粉进行离体培养,通过电镜观察并测定花粉的萌发率与花粉管的生长长度。结果表明,低浓度(0.5～2.0mmol/L)硝酸钙较对照(无钙处理)提高了花粉的萌发率,促进花粉管的生长,以2.0mmol/L硝酸钙处理的花粉萌发率最高(68.5%),与对照相比达到显著水平;而以1.5mmol/L硝酸钙处理的花粉管生长长度最长(255.4μm),比对照达到显著水平。但是加入1.0mmol/LCa2+鳌合剂EGTA时,花粉萌发率为0。以上结果表明钙信号可能调控荔枝的花粉萌发与花粉管生长。     

硼对平邑甜茶幼苗硝态氮吸收、利用及分配特性的影响

以平邑甜茶幼苗为试材,运用~(15)N同位素示踪和非损伤微测技术,研究了不同供硼(硼酸0、1.0、2.0、3.0、4.0、5.0和6.0 mg·L~(-1))水平对平邑甜茶根系生长及氮素吸收、利用和分配特性的影响。结果表明,3.0 mg·L~(-1)硼酸处理的幼苗根系活力及根系形态指标显著高于其他处理,幼苗的全氮量及~(15)N吸收量增幅最大,分别比对照提高了19.4%和75.0%。随供硼水平的增加,植株氮素利用率呈现先增高后降低的趋势,在3.0 mg·L~(-1)硼酸处理时最大,为14.8%,是对照的1.8倍。施硼处理对幼苗的~(15)N分配率有一定的影响,3.0 mg·L~(-1)硼酸处理的根系~(15)N分配率达到最大,且显著高于对照。非损伤微测结果显示,3.0 mg·L~(-1)硼酸处理时,平邑甜茶根系对NO_3~-有强烈吸收且内流速度达到最大,在缺硼和高硼(硼酸0和6.0 mg·L~(-1))处理时有明显外排趋势。因此,3.0 mg·L~(-1)硼酸处理最有利于平邑甜茶根系的生长、根系活力的提高和氮素的吸收利用,而低硼和过量供硼均会抑制根系生长及氮素的吸收利用。     

限水条件下氮肥用量及施氮时期对冬小麦产量、土壤硝态氮含量的影响

在节水栽培条件下,研究了不同施氮量及氮肥施用时期对冬小麦产量、生育期间土壤硝态氮含量的影响。结果表明,冬小麦施氮处理产量均高于N0,N88.5 69处理产量最高,氮肥生理效率则随施氮量增加而显著降低。开花期以及成熟期各施氮处理0~100 cm土体硝态氮含量均明显高于N0,各生育期0~60 cm土层硝态氮含量均随施氮量增加而增加,开花期各处理2 m土体硝态氮含量达到最高值,成熟期20~60 cm土层相同施氮量(157.5,226.5kg/hm2)均表现为氮肥分次施用处理硝态氮含量高于一次性底施处理(N88.5 69>N157.5,N123 103.5>N226.5)。成熟期土壤硝态氮2 m土体累积量随施氮量增加显著增加,且等量氮肥分次施用显著高于一次性底施。     

小型猪特异性麻醉颉颃剂对大鼠脑NO/cGMP信号转导系统的动态影响

为探讨NO/cGMP信号转导系统对小型猪特异性麻醉颉颃剂催醒分子机理的调控,144只Wistar大鼠随机分为对照组和试验组,对照组和试验组再分为早期催醒组、中期催醒组和晚期催醒组。用分光光度法测定脑NOS活性和NO产量,ELISA测定脑cGMP含量。结果显示,小型猪特异性麻醉颉颃剂能明显地激活大鼠相关脑区的NOS活性和NO及cGMP产量,并且大鼠不同脑区NOS活性、NO产量和cGMP含量的变化趋势不仅与大鼠行为学变化相平行,还与不同时期表现出的催醒效果基本吻合。这表明小型猪特异性麻醉颉颃剂的催醒可能与激活特定脑区的NO/cGMP信号转导系统相关。     

诱导型一氧化氮合酶与动物疾病

一氧化氮（nitric oxide,NO)是近年来引起人们特别注意的无机气体自由基，有独特的理化性质和生物学活性，几乎对全身各个系统都有影响，其中诱导型一氧化氮合酶及其催化产生的NO在动物疾病的发生、发展过程中都起着重要的作用。