Diversity and Characterization of Potential H2-Dependent Fe(Ⅲ)-Reducing Bacteria in Paddy Soils

Microbial ferric iron reduction, with organic carbon or hydrogen as the electron donor, is one of the most important biogeochemical processes in anoxic paddy soils; however, the diversity and community structure of hydrogen-dependent dissimilatory iron-reducers remain unknown. Potential H2-dependent Fe(III)-reducing bacteria in paddy soils were explored using enrichment cultures with ferrihydrite or goethite as the electron acceptor and hydrogen as the electron donor. Terminal restriction fragment length polymorphism (T-RFLP) analysis and cloning/sequencing were conducted to reveal bacterial community structure. Results showed that Geobacter and Clostridium were the dominant bacteria in the enrichment cultures. Fe(III) oxide mineral phases showed a strong effect on the community structure; Geobacter and Clostridium were dominant in the ferrihydrite treatment, while Clostridium spp. were dominant in the goethite treatment. These suggested that H2-dependent Fe(III)-reducing bacteria might be widely distributed in paddy soils and that besides Geobacter, Clostridium spp. might also be an important group of H2-dependent Fe(III)-reducing microorganisms.     

养分与CO2交互作用对番茄幼苗生长及一些生理指标的影响

营养液栽培条件下,研究了不同CO2浓度及养分供应强度对番茄幼苗生长及一些生理指标的影响。 发现CO2施肥增加了株高、茎粗、整株的鲜干重,壮苗指数、叶片数、花蕾数、光合作用速率,胞间CO2浓度。 CO2施肥降低了蒸腾速率,气孔导度,这些指标对CO2的响应随营养液浓度的改变而改变。CO2施肥增加了高 养分供应条件下的根冠比,降低了低养分供应强度下的根冠比,反映了番茄在高浓度CO2条件下对养分浓度 改变的适应特征。CO2施肥不仅提高了番茄幼苗对养分的利用能力,而且也减轻了由于养分浓度过高而带来 的负面影响。     

不同化学生态型紫苏的镉耐性及镉富集能力研究

为探究不同化学生态型紫苏的镉耐性与镉富集能力差异,设置不同浓度镉处理,测定了4种化学生态型紫苏种子的萌发指标及其幼苗的镉含量与镉富集特性。结果显示,10.0 mg·L~(-1)镉处理对PKPA型、EK型和PK-I型紫苏种子的发芽率、发芽势无显著影响,但显著抑制了PK-Ⅱ型紫苏种子的萌发。不同浓度镉处理下,不同生态型紫苏各部位的镉含量均表现为:根(1 052.0～5 337.1 mg·kg~(-1))茎(327.6～807.9 mg·kg~(-1))叶(104.8～343.3 mg·kg~(-1)),全株镉含量在348.1～1 416.73 mg·kg~(-1),远高于镉超富集植物的标准(100 mg·kg~(-1))。不同生态型紫苏的镉富集系数(BCF)存在显著差异,PAPK型、PK-Ⅱ型、EK型紫苏的BCF在2.0 mg·L~(-1)镉处理时最高,依次为252.0、300.5、295.3,显著高于PK-Ⅰ型,后者的BCF在5.0 mg·L~(-1)镉处理时最高(265.5),显著高于PAPK型、PK-Ⅱ型和EK型。不同生态型紫苏的镉富集量均以5.0 mg·L~(-1)镉处理时最高,PK-Ⅰ型紫苏镉总富集量为454.0μg·株~(-1),分别是PAPK型、PK-Ⅱ型和EK型的2.48、1.69倍和2.05倍。不同化学生态型紫苏的镉耐性间存在显著差异,镉胁迫下PK-Ⅰ型紫苏具有较高镉耐性及镉富集能力,可用于后续研究紫苏镉耐性作用机制以及镉污染稻田修复的主要种质资源。     

叶面阻控剂对黔中喀斯特地区水稻Cd富集特征的影响

为优选适用于贵州喀斯特地区Cd污染农田水稻生产的叶面阻控剂,在贵州中部典型Cd超标稻田开展田间试验,于水稻分蘖期、抽穗期喷施不同叶面阻控剂作为处理(编号分别为SI、SE、GWY、FE、ZN),以不施叶面阻控剂的处理为对照(CK),在成熟期采集水稻植株样品,探讨不同叶面阻控剂对水稻各部位Cd迁移转化的影响。结果表明:与CK相比,喷施叶面阻控剂对土壤pH、有机质、Cd含量无显著影响。SE、GWY、ZN、SI处理下,水稻产量分别较CK显著(P<0.05)增加13.56%、5.77%、5.74%、7.30%。与CK相比,ZN处理下糙米镉含量降幅最大(56.5%),其次是SE、GWY处理,降幅分别为52.3%和39.4%。与CK相比:SE处理下,水稻茎节的Cd富集系数下降44.8%;ZN处理下,水稻穗轴、糙米中的Cd富集系数分别下降55.0%、58.0%;SI处理下,水稻叶的Cd富集系数提高133.7%。SE、SI处理下,枝梗-稻壳的Cd转移因子分别较CK降低65.8%、40.8%。综上,SE、GWY、ZN能提高水稻产量,降低糙米中的Cd含量,调节Cd在水稻植株各部位的富集与转运,可以用作保障黔中地区Cd污染耕地安全利用的水稻叶面阻控剂。     

CO_2加富对大棚甜瓜农艺性状的影响

以厚皮甜瓜“金蜜”品种为施肥对象 ,研究不同浓度 (10 0 0、12 0 0、14 0 0 μmol/mol)CO2 气肥对其农艺性状的影响。结果表明 :CO2 加富对春季大棚甜瓜生长发育、抗性和品质均有促进作用 ;平均单果重和产量增幅分别为 17.2 0 %～ 2 9.62 %和 10 .40 %～2 9.3 0 % ;CO2 加富适宜浓度为 12 0 0 μmol/mol。     

The impact of free-air CO2 enrichment (FACE) and nitrogen supply on grain quality of rice

Because CO₂ is needed for plant photosynthesis, the increase in atmospheric CO₂ concentration ([CO₂]) has the potential to enhance the growth and yield of rice (Oryza sativa L.), but little is known regarding the impact of elevated [CO₂] on grain quality of rice, especially under different N availability. In order to investigate the interactive effects of [CO₂] and N supply on rice quality, we conducted a free-air CO₂ enrichment (FACE) experiment at Wuxi, Jiangsu, China, in 2001–2003. A long-duration rice japonica with large panicle (cv. Wuxiangging 14) was grown at ambient or elevated (ca. 200 μmol mol⁻¹ above ambient) [CO₂] under three levels of N: low (LN, 15 g N m²), medium (MN, 25 g N m²) and high N (HN, 35 g N m² (2002, 2003)). The MN level was similar to that recommended to local farmers. FACE significant increased rough (+12.8%), brown (+13.2%) and milled rice yield (+10.7%), while markedly reducing head rice yield (−13.3%); FACE caused serious deterioration of processing suitability (milled rice percentage −2.0%; head rice percentage −23.5%) and appearance quality (chalky grain percentage +16.9%; chalkiness degree +28.3%) drastically; the nutritive value of grains was also negatively influenced by FACE due to a reduction in protein (−6.0%) and Cu content (−20.0%) in milled rice. By contrast, FACE resulted in better eating/cooking quality (amylose content −3.8%; peak viscosity +4.5%, breakdown +2.9%, setback −27.5%). These changes in grain quality revealed that hardness of grain decreased with elevated [CO₂] while cohesiveness and resilience increased when cooked. Overall, N supply had significant influence on rice yield with maximum value occurring at MN, whereas grain quality was less responsive to the N supply, showing trends of better appearance and eating/cooking quality for LN or MN-crops as compared with HN-crops. For most cases, no [CO₂] × N interaction was detected for yield and quality parameters. These data suggested that the current recommended rates of N fertilization for rice production should not be modified under projected future [CO₂] levels, at least for the similar conditions of this experiment.     

离子型稀土闭矿区土壤铵态氮富集特征

离子型稀土开采使用的浸矿剂(硫酸铵)造成土壤铵态氮(NH₄⁺-N)残留,带来严重的氮污染,危及生态环境和人体健康,导致稀土矿开采受限。为明确已开采矿区土壤中NH₄⁺-N的富集特征及其影响因素,选择江西省赣州市龙南县一个已闭矿4年的原地浸矿离子型稀土矿山,在山体不同坡位布点,自土表至矿体底板(土体与基岩交界处,深度为5.5～9.7 m)分层采样,并测定了土体中的NH₄⁺-N及其相关的土壤性质。结果表明,矿区土壤NH₄⁺-N含量范围为2.32～1 056.44 mg·kg^-1(263.12±301.59mg·kg^-1),是自然和农田土壤的数倍甚至上百倍。从土体分布来看,矿体部分土壤NH₄⁺-N含量高于其上部土壤,不同土层间差异显著。从不同地形部位来看,NH₄⁺-N的平均含量坡顶>坡...     

环境富集与猪的福利

简述了欧盟对猪圈舍环境富集的强制要求,综述了环境富集对集约化饲养环境中猪行为、生理、肉质的影响,总结了当前富集材料的研究进展,分析了一些富集效果不明显的原因,认为环境富集的研究手段还有待改进。     

富铜酵母发酵条件优化的研究

利用酵母菌具有较强的富集微量元素的特性,试验研究了酵母菌富集微量元素铜的条件优化。从6株酵母菌中筛选出耐铜能力和富集铜能力均较强的J5作为试验菌株。试验结果显示:500ml摇瓶中装入50ml培养基,pH值为4.0～5.5,接种量为4%,30℃条件下摇床培养,最适宜的无机铜源为氯化铜,适宜氯化铜浓度120μg/ml。在此条件下培养所得酵母菌体生物量能达到1.00g/100ml以上,有机铜含量能够达到5000μg/g左右。     

环境富集材料对不同饲养密度条件下肉鸡生产性能的影响

选择21日龄健康的AA肉公鸡816只,研究环境富集材料对不同饲养密度条件下肉鸡生产性能和屠宰性能的影响。试验采用3(饲养密度)×2(环境富集材料)设计,每个处理4个重复。试验结果表明:随着饲养密度的增加,肉鸡日增重和采食量极显著地降低(P<0.01),料肉比明显增加(P<0.01),添加环境富集材料除能使高饲养密度组的死亡数大幅度降低外,对生产性能的其他指标影响不明显(P>0.01);添加环境富集材料能使不同饲养密度水平下饲养的肉鸡的腹脂率明显下降(P<0.05)。研究表明:高饲养密度降低了肉鸡的日增重和采食量,增加了料肉比;在肉鸡舍中添加环境富集材料降低了肉鸡的腹脂率,且在一定范围内可提高屠体率。