不同氮肥处理春玉米温室气体的排放

春玉米种植过程中会造成直接和间接的温室气体排放。该文采用生命周期的方法综合评估了不同施肥处理下的温室气体排放,目的是筛选出既能保证产量和经济效益,又能有效减排的措施。4种不同的施肥处理包括：当地传统施肥方式、尿素处理、硫包衣尿素、尿素添加双氰胺处理。采用静态箱-气相色谱法连续监测土壤 N2O排放,并计算了不同肥料处理的N2O排放总量;计算了肥料生产、运输、农田耕作管理能源消耗、种子生产等的温室气体排放,计算了春玉米全生命周期中温室气体排放总量、单位产量、万元产出的温室气体排放量。结果表明,不同处理施肥造成的N2O排放量、全生命周期中温室气体排放总量、单位产量排放强度和净收益排放强度的排序均为传统施肥处理＞尿素处理＞尿素添加双氰胺处理＞硫包衣尿素处理。传统施肥处理的N2O排放总量极显著高于其他3个处理（P＜0.01）;硫包衣尿素处理的N2O排放总量显著低于尿素处理（P＜0.05）,与尿素添加双氰胺处理无显著差异（P＞0.05）。不同处理的全生命周期排放总量、单位玉米产量排放量和万元净产值排放量变化范围分别是2.56～4.11 t/(hm2·a)、216.6～364.1 kg/t和1.15～2.19 t/万元。和传统施肥处理相比,硫包衣尿素处理可分别降低温室气体（greenhouse Gas,GHG）排放总量、单位玉米产量排放和万元净产值碳排放37.8%、40.5%和47.3%,尿素添加双氰胺处理可降低36.5%、38.6%和45.9%。化肥尤其是氮肥的生产在春玉米种植过程中对碳足迹的贡献最大,占42.4%～55.0%;玉米生产过程中的N2O排放次之,占20.8%～26.1%。在保证粮食产量和经济效益的前提下,硫包衣尿素处理和尿素添加双氰胺处理2种施肥方式具有较低的碳排放强度,可作为当地较为合理的施肥方式进行推广。     

福建省N_2O排放清单及其特征分析

通过核算福建省1980-2013年N_2O的排放清单,分析了N_2O的排放特征.结果表明:1980-2013年,福建省N_2O总排放量从19.2 Gg增加到37.6 Gg;在N_2O的排放源中,按照排放贡献比例从大到小排列依次为农用地、畜禽粪便管理、废水处理和能源消费活动;而按照增长速度从大到小排列依次为能源消费活动、废水处理、农用地和畜禽粪便管理.表明减少农田氮肥施用量是减少福建省N_2O排放的关键.     

外源一氧化氮对不同温度处理的牡丹花瓣生理特性的影响1）

以5年生牡丹品种‘乌龙捧盛’为试材,采用叶面喷施的方法研究外源一氧化氮对不同温度处理牡丹花瓣生理特性的影响。结果表明：分别经5、25℃处理的牡丹花瓣超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性均高于15℃处理的,而经35℃处理的降低了SOD和CAT的活性,提高了POD的活性;分别经5、25、35℃处理的脯氨酸质量分数、丙二醛（ MDA）质量摩尔浓度和可溶性糖质量分数均高于15℃处理的,以经35℃处理的最高;可溶性蛋白质量分数随温度的升高而增加;总酚和类黄酮质量分数随温度的升高而降低。经0．2 mg· L－1硝普钠处理后,不同处理组牡丹花瓣的SOD、POD和CAT活性均有不同程度地提高,脯氨酸、可溶性糖和可溶性蛋白质量分数增加,各温度处理下MDA质量摩尔浓度均有所降低,总酚和类黄酮的质量分数增加,这有利于缓解不适温度对牡丹花瓣造成的损伤,维持其正常的生长代谢。     

不同形态磷在砂土中的移动性研究(英文)

预测土壤中磷的长期淋洗性需要了解土壤特性和不同形态磷的行为.本研究用模拟试验评估了不同磷负荷砂质土壤中不同形态磷的移动性.分别从浙江省衢州市和温州市采集具不同磷含量的蔬菜地土壤,每一地点分别采集2个深度的土壤(0～10 cm和10～30 cm),表层土壤(0～10 cm)通过添加不同量的磷酸盐、CaCO和无定形氧化铁,形成研究需要的不同磷含量和不同磷形态的系列土壤样品;淋洗柱长30 cm,由10 cm经培养处理的表层(0～10 cm)土壤和未经培养处理的亚表层土壤(10～30cm)构成,每一淋洗土柱连续经历12个循环的0.002 mol?L-1CaCl2溶液淋洗,收集的淋洗液用于分析钼酸反应总磷(TRP)、可溶态钼酸反应磷(DRP)和颗粒态钼酸反应磷(RPP);试验结束后鉴定土壤中水溶态磷、MehlichⅢ-P和磷的化学形态变化.结果表明:添加无定形氧化铁和碳酸钙可显著改变砂土中磷的形态,降低土壤磷的有效性;无定形态氧化铁在降低土壤磷有效性方面的作用大于碳酸钙;淋洗液中磷的形态主要为DRP,颗粒态磷占总磷的比例为1.2%～39.8%;TRP和DRP的损失与培养处理后表土中磷含量存在显著的相关.相关分析和淋洗试验后土壤中磷形态变化结果都表明:表土柱中淋移的磷主要来源于水溶性磷(H2O-P)和NaHCO3-P,与NaOH-P、HCl-P和残余磷的相关不明显;从表土淋失的磷有27.1%～54.2%被淋出土体,其余下移至10～30 cm土层中.研究结果还表明,添加无定形氧化铁可增加土柱中颗粒态磷的迁移.     

棉花响应UV-B辐射的信号初探

以3种棉花为供试材料,研究紫外线-B(UV-B)辐射及外源SNP、ABA叠加处理对棉花幼苗表观形态及内源H2O2与NO水平的影响。结果表明,UV-B辐射引起棉花幼苗叶片呈现锈色伤斑,离体叶片明显失水萎蔫。叶片外源涂抹SNP、ABA能减轻UV-B辐射引起的幼叶伤斑与萎蔫症状,缓解UV-B辐射所造成的伤害。DAB及DAF-2DA染色结果显示,UV-B辐射引起棉花内源H2O2与NO含量增加,而NO的释放通过减少H2O2积累减轻紫外辐射对棉花的伤害。ABA预处理可增强棉花对紫外伤害的耐受能力,且与H2O2与NO的释放密切相关。UV-B辐射对棉花生长造成伤害,H2O2、NO及ABA都参与棉花应答UV-B胁迫的信号转导过程。     

Assessment of Uterine Vascular Perfusion During the Estrous Cycle of Mares in Connection to Circulating Leptin and Nitric Oxide Concentrations

The objective of this study was to find difference in vascular perfusion of uterine horns or uterine body throughout the estrous cycle and their relation to circulating nitric oxide and leptin concentrations. Five cyclic mares were subjected to transrectal Doppler ultrasonography and blood sampling for 18 days. Area of color and power Doppler modes was measured in pixels. Day (P = .0001) of the estrous cycle and ovulation (P = .0001) influenced uterine blood flow. Uterine body blood flow directed away from the transducer (blue, P = .0001) increased from day −5 until day 0 (day of ovulation), and its power (P = .0001) blood flow increased from day −6 until day 0; then, both decreased until days 12 and 10, respectively. Conversely to the contralateral uterine horn, ipsilateral uterine horn blood flow directed away from the transducer (blue, P = .0001) increased from day −5 until day −1, and its power (P = .0001) blood flow increased from day −6 until day 0; then, both decreased until day 10. Nitric oxide concentrations (P = .0001) attained two major peaks; the first on day −3 and the other persisted from day 2 until day 5. Leptin concentrations increased (P > .001) with a maximum value on day 0 and then decreased until a minimum value on day 9. In conclusion, during the estrous cycle, ipsilateral uterine horn and uterine body blood vessels had similar blood flow. Both leptin and nitric oxide played a role during follicle growth, ovulation, and corpus luteum development and modulated uterine blood flow before and after ovulation.     

EFFECT OF NITRIC OXIDE ON ALFALFA SEED GERMINATION UNDER NaCi STRESS

以甘农4号、阿尔冈金2个品种苜蓿为材料,用一氧化氮（NO）供体硝普钠、NO清除剂c-PTIO、一氧化氮合酶抑制剂N-硝基．L-精氨酸甲脂、硝酸还原酶抑制荆钨酸钾及硝普钠类似物亚铁氰化钠（不产生NO）处理苜蓿种子,研究NO对盐胁迫下苜蓿种子萌发的生理效应。结果表明,盐胁迫显著抑制了2个苜蓿品种的发芽率、胚芽和胚根长及幼苗干重（P〈0．05）,降低种子萌发过程中α、β-淀粉酶、蛋白水解酶活性,抑制淀粉水解和可溶性糖积累（P〈0．05）;盐胁迫下添加外源NO则使2个品种苜蓿α、β淀粉酶、蛋白水解酶活性、种子发芽率显著提高（P〈0．05）,淀粉含量降低,可溶性糖含量升高、胚芽和胚根长及幼苗干重显著增加（P〈0．05）;NO供体SNP的类似物亚铁氰化钠对盐胁迫下苜蓿种子萌发的各项指标无明显影响;施用NO清除剂c-PTIO、硝酸还原酶抑制剂钨酸钾和一氧化氮合酶抑制剂N-硝基-L-精氨酸甲脂具有降低苜蓿种子萌发的效应（P〈0．05）。因此,盐胁迫抑制苜蓿种子的萌发,而添加外源NO是缓解这种抑制作用的有效途径,内源NO也可能参与盐胁迫下苜蓿种子萌发的调节,且通过NOS和NR途径产生的NO在缓解盐胁迫抑制苜蓿种子萌发中可能起关键作用。     

Carbon nanomaterial addition changes soil nematode community in a tall fescue mesocosm

Carbon nanomaterials have been widely used in industry and inevitably enter the environment. However, there is little information about their influence on the abundance and diversity of soil nematode community. We evaluated the impact of three kinds of carbon nanomaterials (graphene, graphene oxide, and carbon nanotubes) on the abundance and diversity of soil nematodes after growing tall fescue for 130 d using a laboratory pot experiment. A total of 29 genera of nematodes were identified in all the treatments. Carbon nanomaterials significantly increased the abundance of total nematodes and plant parasites. The presence of graphene and graphene oxide increased the numbers of bacterivores, and graphene benefited fungivores. The total nematode abundance was 1.9-2.9 times greater in the carbon nanomaterial treatments than in the control with no carbon nanomaterial addition. However, graphene oxide and carbon nanotubes decreased the values of nematode community parameters, e.g., diversity, species richness, and structure index. Compared with the control, the addition of graphene resulted in a community with a higher plant-parasitic index (i.e., the maturity index of the plant-parasitic nematodes). Overall, our findings highlight that the addition of carbon nanomaterials has a negative influence on the composition and diversity of the nematode community, simplifying the community structure.     

Role of nitrite and nitric oxide in the processes of nitrification and denitrification in soil: Results from N tracer experiments

Recent research has proven soil nitrite to be a key element in understanding N-gas production (NO, N₂O, N₂) in soils. NO is widely accepted to be an obligatory intermediate of N₂O formation in the denitrification pathway. However, studies with native soils could not confirm NO as a N₂O precursor, and field experiments mainly revealed ammonium nitrification as the source of NO. The hypothesis was constructed, that the limited diffusion of NO in soil is the reason for this contradiction. To test this diffusion limitation hypothesis and to verify nitrite and NO as free intermediates in native soils we conducted through-flow (He/O₂ atmosphere) ¹⁵N tracer experiments using black earth soil in an experimental set up free of diffusion limitation. All of the three relevant inorganic N soil pools (ammonium, nitrite, nitrate) were ¹⁵N labelled in separate incubation experiments lasting 81 h based on the kinetic isotope method. During the experiments the partial pressure of O₂ was decreased in four steps from 20% to about 0%. The net NO emission increased up to 3.7 μg N kg⁻¹ h⁻¹ with decreasing O₂ partial pressure. Due to the special experimental set up with little to no obstructions of gas diffusion, only very low N₂O emission could be observed. As expected the content of the substrates ammonium, nitrate and nitrite remained almost constant over the incubation time. The ¹⁵N abundance of nitrite revealed high turnover rates. The contribution of nitrification of ammonium to the total nitrite production was approx. 88% under strong aerobic soil conditions but quickly decreased to zero with declining O₂ partial pressure. It is remarkable that already under the high partial pressure of 20% O₂ 12 % of nitrite is generated by nitrate denitrification, and under strict anaerobic conditions it increases to 100%. Nitrite is present in two separate endogenous pools at least, each one fed by the nitrification of ammonium or the denitrification of nitrate. The experiments clearly revealed that nitrite is almost 100% the direct precursor of NO formation under anaerobic as well as aerobic conditions. Emitted N₂O only originated to about 100% from NO under strict anaerobic conditions (0-0.2% O₂), providing evidence that NO is a free intermediate of N₂O formation by denitrification. To the best of our knowledge this is the first time that NO has been detected in a native soil as a free intermediate product of N₂O formation at denitrification. These results clearly verify the “diffusion limitation” hypothesis.     

免耕对农田土壤N_2O排放影响及作用机制研究进展

免耕在促进农业可持续发展和有效分馏大气碳的同时还可影响土壤N2O排放,但迄今为止关于免耕对农田土壤N2O排放影响的研究结果却不尽一致,正效应间或负效应都存在。本文综述了免耕条件下土壤理化性状和生物性状的变化及其对N2O排放的影响,并指出实施免耕后土壤反硝化强度变化程度的不同是导致免耕对N2O排放影响效应不同的主要原因,最后提出了一些有待研究的问题。