抗除草剂固氮蓝藻研究进展

分析了近10年来国内外的相关文献,对抗除草剂固氮蓝藻研究进行综述.重点介绍了除草剂对固氮蓝藻生长和固氮能力的影响,探讨了固氮蓝藻抗除草剂的机理,并就今后的研究内容和方向进行展望.     

新型固氮菌剂对长豇豆生长发育的影响

研究了施用催娩克氏菌菌剂对长豇豆的影响。结果表明 ,用 5 %菌剂浸种、在移植第 1d和 2 0d用0 5 %菌剂喷施叶面和淋根 ,可促进长豇豆种子萌发、提高幼苗素质、促进荚果发育及提高小区产量     

玉米内生固氮菌的分离鉴定及其促生长作用研究

从玉米东单90和郑单958健康鲜植株中分离纯化内生细菌,利用乙炔还原法测定分离物的固氮酶活性,得到2株固氮酶活性较高的菌株SD1A和SD2A,分别为3284.3C2H4·h-1·mL-1和3206.8nmo1C2H4·h-1mL-1;将SD1A和SD2A的纯培养物对植物分别进行土培和水培回接试验,结果均能从植物体内重新分离到出发菌株,表明SD1A和SD2A为内生固氮菌;通过对菌株理化特性试验,结果证明二者均为克雷伯氏菌属(Klebsiella trevisan).用SD1A和SD2A处理的植株在水培试验中,株高分别为35.95cm 和35.32cm,地上部干重分别为0.106g和0.101g,与对照植株相比(株高30.38cm、地上部干重0.085g)达差异显著水平;土培试验中株高分别为68.18cm和68.58cm,地上部干重分别为1.06g和1.09g,根干重分别为0.160g和0.185g,与对照植株相比(株高62.00cm、地上部干重0.64g、根干重0.085g)均达差异显著水平,表明SD1A和SD2A对幼苗期玉米具有显著的促生长作用.     

固氮螺菌 (Azosprillum brasilense)NO40在红壤性水稻土上的接种效应

裂区设计田间试验结果表明，在3个供氮水平下接种巴西固氮螺菌(Azospirillum brasilense)NO40，使分蘖期与灌浆期水稻根际及根内的固氮菌数量均比对照明显增加，而土体中的固氮菌数量未见明显变化；同时，接种该菌株可显著提高分蘖期与灌浆期水稻新展开叶的叶绿素含量及水稻株高，在低氮水平下使水稻单株干物重和单株籽粒产量有所提高。     

耐氨固氮菌对刺黄瓜生长、产量及品质的影响

研究了施用耐氨型催娩克氏菌对刺黄瓜的影响。结果表明 ,用 5 %菌液浸种、在移植第 1d和 2 0d用 0 5 %菌液喷施叶面和淋根 ,可分别促进种子出苗、幼苗生长、提高小区产量及果实品质 ;用相同处理粉剂也有类似效果 ,但不如菌液明显。     

耐氨固氮菌浸种对低温胁迫下黄瓜幼苗保护酶活性的影响

用耐氨固氮菌浸种处理黄瓜种子,研究了低温胁迫下黄瓜幼苗保护酶活性的变化。结果表明:5℃低温胁迫2 d,清水组黄瓜幼苗叶片相对电导度、MDA含量及CAT活性显著升高,SOD及POD活性、叶绿素含量显著降低,恢复1 d,这种差异更显著,活性变化不明显;经耐氨固氮菌浸种处理后,菌液组黄瓜叶片叶绿素含量及保护酶活性显著增强,5℃低温胁迫2 d,也表现出清水组的变化规律,但CAT活性显著降低,恢复1 d,菌液组黄瓜叶片相对电导度、MDA含量则显著低于清水组(P<0.05),叶绿素含量则显著高于清水组(P<0.05), SOD及CAT活性显著升高(P<0.05),POD和AsA-POD活性则降低。结果显示,经耐氨固氮菌浸种处理后, 黄瓜幼苗提高了机体的抗氧化酶活性而增强耐寒能力,避免低温的伤害。     

耐氨固氮菌对菜心和小白菜的施用效果分析

研究了施用耐氨固氮型的催娩克氏菌和阴沟肠杆菌混合菌剂以菜心和小白菜幼苗素质及小区产量的影响。结果表明，用耐氨固氮菌作种子处理、移苗后喷施和淋根可促进菜心和小白菜生长，提高幼苗素质及小区产量。     

耐氨固氮菌对菜心和小白菜的施用效果初探

研究了施用耐氨固氮型的催娩克氏菌和阴沟肠杆菌混合菌剂对菜心和小白菜幼苗素质及小区产量的影响。结果表明 ,用耐氨固氮菌作种子处理、移苗后喷施和淋根可促进菜心和小白菜生长 ,提高幼苗素质及小区产量。     

Increasing N abundance in the northwestern Pacific Ocean due to atmospheric nitrogen deposition

The relative abundance of nitrate (N) over phosphorus (P) has increased over the period since 1980 in the marginal seas bordering the northwestern Pacific Ocean, located downstream of the populated and industrialized Asian continent. The increase in N availability within the study area was mainly driven by increasing N concentrations and was most likely due to deposition of pollutant nitrogen from atmospheric sources. Atmospheric nitrogen deposition had a high temporal correlation with N availability in the study area (r = 0.74 to 0.88), except in selected areas wherein riverine nitrogen load may be of equal importance. The increase in N availability caused by atmospheric deposition and riverine input has switched extensive parts of the study area from being N-limited to P-limited.     

长期氮磷不同施用量对土壤细菌、硝化与反硝化微生物数量的影响

为研究长期施用氮、磷肥对土壤微生物的影响,利用荧光定量PCR方法,比较6种不同氮磷施用量处理下土壤细菌、硝化与反硝化微生物的数量差异。结果表明:1)与不施肥相比,施氮磷肥显著提高了细菌16SrRNA基因、氨氧化古菌和细菌amoA基因和反硝化细菌nirK和nosZ基因拷贝数;2)与不施肥相比,低水平(T1)到高水平(T5)氮磷肥显著提高了细菌和氨氧化古菌数量,中低水平(T2)到高水平(T5)氮磷肥显著提高了氨氧化细菌数量,中、高水平(T3-T5)氮磷肥显著提高了nirK和nosZ型反硝化细菌数量,但施氮磷肥对nirS型反硝化细菌数量影响不显著;3)各处理中,氨氧化古菌amoA基因拷贝数显著高于氨氧化细菌amoA基因,反硝化细菌nosZ基因拷贝数显著高于nirK和nirS基因,nirK基因拷贝数显著高于nirS基因;4)细菌、氨氧化古菌和细菌及nirK和nosZ型反硝化微细菌数量与土壤pH呈显著负相关关系,与其他土壤理化性质均呈显著正相关关系。此外,硝态氮含量与氨氧化古菌和细菌数量显著相关,但与反硝化细菌数量无显著相关关系。综上所述,长期施用氮磷肥显著提高了土壤细菌、氨氧化古菌和细菌及nirK和nosZ型反硝化细菌的数量,且这些微生物的数量变化对氮磷肥施用水平的响应存在差异。     

CO2 snow depth and subsurface water-ice abundance in the northern hemisphere of Mars

Observations of seasonal variations of neutron flux from the high-energy neutron detector (HEND) on Mars Odyssey combined with direct measurements of the thickness of condensed carbon dioxide by the Mars Orbiter Laser Altimeter (MOLA) on Mars Global Surveyor show a latitudinal dependence of northern winter deposition of carbon dioxide. The observations are also consistent with a shallow substrate consisting of a layer with water ice overlain by a layer of drier soil. The lower ice-rich layer contains between 50 and 75 weight % water, indicating that the shallow subsurface at northern polar latitudes on Mars is even more water rich than that in the south.     

On the fringes of conquest: maya-spanish contact in colonial belize

The defeat of the Aztecs of Mexico by Hernán Cortés in 1521 was but the beginning of a long and torturous conquest of Central America that did not always result in the mastery of people and production for which the Spanish had hoped. The Maya of the resource-poor Yucatán peninsula were spared the heavy colonial hand that held fast to central Mexico and its riches. In addition, the dense forests of the peninsula served as a haven for refugees fleeing oppressive conditions in colonial towns. Despite the paucity of documentary information on Maya communities of the frontier, knowledge of Maya-Spanish relations in the 16th and 17th centuries has advanced in recent years through archeological and ethnohistorical research. Work in one region of the Maya lowlands has brought us closer to an understanding of the early interaction of the rulers and the ruled.     

Isolation of the Heterofullerene C59N as Its Dimer (C59N)2

The heterofullerene ion C(59)N(+) is formed efficiently in the gas phase during fast atom bombardment mass spectroscopy of a cluster-opened N-MEM (N-methoxyethoxy methyl) ketolactam. This transformation is shown to occur also in solution in the presence of strong acid, affording biazafullerenyl (C(59)N)(2) in good yield. It is proposed that the azafullerene dimer is formed upon in situ reduction of the highly reactive azafulleronium ion. The isolation and characterization of biazafullerenyl opens a viable route for the preparation of other heterofullerenes in solution.     

利用分子标记确定从水稻3N×2N组合中 得到的F2群体稳定性

同源三倍体株系43是从水稻双胚苗株系9004群体中筛选出来的。用它作为母本和正常的二倍体粳稻品种"中丹2号”杂交,得到了具有双亲性状的二倍体后代,收获其自交结实种子,次年获得一个表现稳定一致的F2群体,编号"942”。为了证实这个群体稳定的真实性,利用RFLP和SSR2种分子标记进行了验证。结果表明这个群体在分子水平上是稳定一致的。     

氧气浓度对小麦-玉米轮作农田土壤剖面N2和N2O产生的影响

反硝化过程是集约化农田土壤剖面硝态氮(NO₃^--N)去除的重要途径。但对土壤剖面反硝化氮气(N₂)产生速率的准确定量很难,尤其不同深度的土壤氧气(O₂)浓度状况如何影响土壤N₂的产生仍不清楚。本研究依托集约化管理的冬小麦-夏玉米轮作田间长期定位试验(始于2006年),采集传统施肥处理0～2.5 m剖面的原状土柱,并基于在玉米生长季田间原位观测的不同深度土壤O₂浓度和温度状况,设置不同O₂浓度水平(15.0%、12.0%、2.5%和0)和培养温度(26℃和20℃),采用氦培养-直接测定N₂法测定3个不同深度(0～0.2、0.5～0.7 m和2.0～2.2 m)土壤N₂O和N₂产生速率。结果显示:无论是有氧还是无氧条件,土壤剖面N₂和N₂O的产生均表现为表层高于深层;有氧条件下(2.5%～15.0%O₂)土壤...     

水稻优化群体质量调控技术的应用效果

为提高水稻群体质量指标,于１９９９年旱季在晋江市实施由福建省农业厅制订的“优控法”栽培方案。结果表明,“优控法”与习惯栽培技术对比,水稻成穗率提高１２．１个百分点,有效叶面积比率高７．２个百分点,结实率高１．６２个百分点,千粒重高０．４４ｇ,单位面积产量增幅达１７．３％。     

Self-similarity in the distribution and abundance of species

If the fraction of species in area A that are also found in one-half of that area is independent of A, the distribution of species is self-similar and a number of observed patterns in ecology, including the widely cited species-area relationship connecting species richness to censused area, follow. Self-similarity also leads to a species-abundance distribution, which deviates considerably from the commonly assumed lognormal distribution and predicts considerably more rare species than the latter. Because the abundance distribution is derived under the condition of self-similarity, it may be widely applicable beyond ecology.     

高浓度CO2处理后土壤N2O排放特征

土壤被认为是大气氧化亚氮(N2O)的重要生物排放源.随着大气CO2浓度升高,土壤N2O排放规律可能发生改变.无锡FACE(Free-air CO2 Enrichment)基地至2003年已运行2年,分别采集Ambient(背景大气CO2浓度处理)和FACE(背景大气CO2浓度 200 mmol·mol-1处理)农田土壤,调节含水量至40%WFPS,在25℃室内有氧预培养7 d后,按250 μgN·-1添加NH4NO3,将含水量调节至80%WFPS,在25℃进行有氧培养7 d.在此培养期间,定期测定施肥后土壤N2O和CO2排放速率,探讨来自田间Ambient和FACE土壤N,2O排放差异及其可能的影响因素.结果表明,所有土壤N2O和CO,2排放速率均随培养时间延长而迅速递减,来自Ambient处理的土壤N,2O和CO,2排放速率均高于来自FACE处理的土壤相应排放量,且土壤N,2O与CO,2排放速率存在显著正相关.通过比较培养前后土壤交换态NH,4 和NO,3-含量的变化,显示培养过程中可能存在相当量的微生物氮固持,有必要加强相关研究.     

巢湖流域河流沉积物N2O释放对水体溶存N2O贡献研究

2010年11月在巢湖支流丰乐河与杭埠河采用现场培养和实测方法研究了沉积物N2O释放对水体（水柱）溶存N2O的影响,并采用NO-3削减法估算了沉积物的反硝化速率。研究结果表明,丰乐河与杭埠河N2O平均溶存浓度分别为0.26±0.10（SD）μg N-N2O·L-1和0.18±0.04（SD）μg N-N2O·L-1,饱和度分别为186%和151%,表明两条河流为大气N2O的潜在释放源。丰乐河与杭埠河沉积物-水界面N2O平均释放通量分别为0.39±0.44、0.15±0.16 μg N-N2O·m-2·h-1,由此可分别贡献水体中约89% 和45%的溶存N2O。对河流沉积物的反硝化速率估算结果表明,丰乐河与杭埠河沉积物反硝化速率分别为0.12±0.07、0.10±0.05 mg N·m-2·h-1,与已有的沉积物反硝化速率报道相比较低。     

粤北坡岗地木薯主产区土壤有效氮、磷、钾丰缺指标研究

在粤北翁源、乳源、浈江等地开展坡岗地木薯"3414"肥效试验,按照Cate-Nelson方法,根据缺素处理(-N、-P、-K)占全肥处理(NPK)的相对产量数据与土壤有效养分测定值之间的关系,建立对数拟合方程,以相对产量<50%、50%～75%、75%～90%、90%～95%和>95%为标准,研究土壤有效氮、磷、钾供应的丰缺临界指标。结果表明,粤北坡岗地木薯产区土壤碱解氮缺乏临界值为66.2 mg/kg,高产临界值为70.5 mg/kg,缺乏土样占测试土样的70%;土壤有效磷缺乏临界值为11.3 mg/kg,高产临界值为14.1 mg/kg,缺乏土样占测试土样的80%;土壤有效钾缺乏临界值为61.0 mg/kg,高产临界值为71.3 mg/kg,缺乏土样占测试土样的70%。研究结果可为粤北坡岗地高效施肥提供理论依据。