新疆黄萎病发病程度不同棉田土壤细菌群落结构差异分析

新疆棉区棉花黄萎病发生危害严重,提高该病的生态防控技术对实现棉花"化肥、农药"减施增效有重要意义.文章以阿克苏、石河子和库尔勒三地棉花黄萎病不同发生程度棉田土壤为研究对象,利用高通量测序技术对土壤细菌种群结构进行研究,并分析土壤理化性质与细菌多样性及种群结构的相关性,以期揭示棉田土壤的细菌群落结构差异及主要影响因子,为...     

红壤立体栽培模式中玉米氮、磷、钾配方施肥数学模型的研究

采用氟、磷、钾化肥三因素通用旋转组合设计，通过计算机模拟寻优，建立了湘南砂岩红壤玉米－大豆立体栽培模式中玉米施肥量－产量、玉米施肥量－利润数学模型；优选出玉米产量和利润最高的各10套施肥方案；计算出玉米最高产量的施肥量为：尿素750kg／hm2，过磷酸钙1125kg／hm2，氯化钾332kg／hm2，N∶P2O5∶K2O＝1∶0.39∶0.58；计算出玉米最佳经济效益施肥量为：尿素712.8kg／hm2，过磷酸钙1125kg／hm2，氯化钾285.2kg／hm2，N∶P2O5∶K2O＝1∶0.41∶0.52．玉米与大豆的产量间以及两者的利润间均呈极显著正相关．     

Phosphorus in Sediments of Lake Edku, Egypt. The Influence of Chemical and Grain Size Parameters

Lake Edku is one of the Nile Delta shallow brackish water coastal lagoons with communications with the southeastern Mediterranean.

Sediment samples were recovered from the top 10 cm of the lake bottom to study principally their total, inorganic and organic phosphorus. Related sediment parameters such as particle size, organic carbon, carbonate and iron contents were also studied in detail.

It is shown that the lake sediments are generally a sand-silt-clay mud enriched with carbonate (11.4-42%), organic carbon (0.9-11.4%) and iron (1.6-5.6%).

The total phosphorus content in these sediments is 503-1329 μg/g, inorganic phosphorus, 468-954 μg/g and organic phosphorus, 35-526 μg/g.     

有机磷细菌的分离鉴定及其对MC-RR的响应(The Isolation and Identification of Organic Phosphorus Bacteria and Its Response to MC-RR)

从云南滇池水样中分离出具有解磷能力的有机磷细菌P-2,并利用现代分子生物学技术进行了初步鉴定.用0.01、5mg·L-1微囊藻毒素(MC-RR)处理有机磷细菌P-2,研究了MC-RR对其生长、细胞内酸碱磷酸酶活性(ACP和AKP)以及培养液中可溶性磷酸盐含量的影响.结果表明,高浓度MC-RR能显著抑制有机磷细菌的生长,延缓其细胞增殖,抑制细胞内酸碱磷酸酶活性以及培养液中可溶性磷酸盐含量的升高,因而可能改变或减缓生态系统中磷循环的进程,这表明微囊藻毒素在一定程度上可能调节水体细菌功能群落.     

磷及环境因子对太湖梅梁湾藻类生长及其群落影响

在太湖梅梁湾进行的围隔试验表明,藻类生长与水华形成受气候(如水温、风浪)与营养因子(如N,P)影响。统计分析发现各点硝态氮均与叶绿素a显著负相关,在不同围隔中水温、总磷、总氮等与叶绿素a显著相关。各围隔中优势种主要为蓝藻,尤其是微囊藻类。加磷对藻类生长与群落结构均有影响,但磷营养不是目前太湖水华爆发的关键因素。     

黄红壤上烟草对钾的反应及种烟后土壤钾的变化

黄红壤上烟草对钾的反应及种烟后土壤钾的变化马友华，李道林，陈邦本，方明（安徽农业大学土化系，合肥２３００３６）（南京农业大学资环系）我国南方亚热带的红壤是我国植烟面积较大的土类，适用于种植各种类型的烟草［１］。烟草是喜钾作物，近年来我国南方在烟草种植...     

不同土壤水分条件下添加硅对紫花苜蓿茎叶和土壤氮磷钾含量的影响

为提高植物氮磷钾利用能力,采用盆栽试验研究了不同土壤水分条件下添加硅对紫花苜蓿(Medicago sativa)茎叶和土壤氮、磷、钾含量的影响.结果表明,土壤含水量为饱和含水量的35%和80%时添加硅对紫花苜蓿生物量没有明显影响,而土壤含水量为饱和含水量的50%和65%时则显著提高了紫花苜蓿生物量(P<0.05);添加硅对紫花苜蓿茎叶内氮含量没有显著影响,但显著提高了茎叶内钾和磷含量(P<0.05);添加硅对土壤全氮、速效氮、全钾和全磷含量没有显著影响,而显著提高了土壤速效磷含量(P<0.05),显著降低了土壤速效钾含量(P<0.05).说明添加硅能够显著增加紫花苜蓿茎叶内磷和钾的积累量,刺激土壤速效磷释放,降低土壤速效钾含量.     

The Impact of Agriculture On Dissolved Nitrogen and Phosphorus Cycling in Temperate Ecosystems

Although most research has focussed on inorganic nutrient forms of nitrate (NO^-₃) and phosphorus (PO³₄) in runoff and receiving waters, nitrogen loss from agricultural land can also occur in organic and ammonium-nitrogen form; phosphorus losses, although often dominated by particulate transport, may occur in soluble organic and inorganic form. Furthermore, fluxes between different species may take place during transport from the land to the stream and as a result of in-stream, in-river or in-lake transformations. Knowledge of the spatial and temporal variation in all nitrogen species and phosphorus fractions in a drainage basin is therefore essential if the wider environmental significance of elevated nutrient concentrations in natural waters are to be assessed. This paper reviews recent work on N and P losses from agricultural land and presents some results from two intensive agricultural catchments: Slapton, Devon and the river Windrush catchment in the Cotswolds.     

不同磷初始浓度对紫萍生长及磷吸收效率的影响

采用室内模拟培养试验方法,研究不同磷初始浓度对紫萍生长及磷吸收效率的影响。结果表明,水体初始ρ（磷）为3.0 mg.L-1时,紫萍相对生长率最高,生长繁殖速度最快。当初始ρ（磷）为0.3～3.0 mg.L-1时,紫萍对水体中磷的去除率在70%以上。紫萍累积吸磷量和磷吸收能力均随磷初始浓度的升高而增加,但当初始ρ（磷）为45.0 mg.L-1时,紫萍累积吸磷量和单位鲜质量紫萍吸磷量均明显下降。当初始ρ（磷）≤1.5 mg.L-1时,紫萍体内酸性磷酸酶活性升高,但随着低磷胁迫时间的延长,低磷条件和高磷条件间酸性磷酸酶活性差异减小。     

蜡蚧轮枝菌入侵蚧虫表皮过程中蛋白酶和几丁质酶的作用

研究了蜡蚧轮枝菌两个菌株No.V3.4504和No.V3.4505感染沙里院褐球蚧的外观症状、入侵体壁的过程及胞外蛋白酶与几丁质酶的作用.结果发现.用菌株No.V3.4504的孢子悬浮液感染蚧虫2 d后,在虫体表面蜡粉稀薄的位置和柔软的虫体腹面出现了菌丝,5 d后菌丝覆盖虫体,7 d后菌丝层加厚,虫体开始死亡.显微切片观察.在体壁的外表皮、内表皮和真皮层都发现了菌丝.说明该菌已侵染成功.以蚧虫的表皮为培养基对这两个菌株连续培养8 d,发现菌株No.V3.4504的蛋白酶活性在前6天连续上升,最大值为(33.94±1.61)U/g,然后降低;几丁质酶活性在前期维持在一个较低水平,d 5开始增加,最大值为(7.28±1.36)U/g.菌株No.V3.4505的蛋白酶和几丁质酶的活性变化趋势与No.V3.4504相似.说明蛋白酶在菌丝侵染体壁的前期发挥了作用,降解表皮中的蛋白质,使几丁质暴露,诱导几丁质酶的大量产生,从而分解几丁质.图3表2参22     

长期施肥条件下水稻土磷素分布特征及对水环境的污染风险

对太湖地区稻麦轮作黄泥土进行23 a长期施肥试验,设14种处理:不施肥(C0)、氮肥(CN)、氮钾肥(CNK)、氮磷肥(CNP)、磷钾肥(CPK)、氮磷钾肥(CNPK)、稻草加氮肥(CRN)、有机肥(M0)、有机肥加氮(MN)、有机肥加氮钾(MNK)、有机肥加氮磷(MNP)、有机肥加磷钾(MPK)、有机肥加氮磷钾(MNPK)、有机肥加稻草加氮(MRN)。结果表明:(1)与无磷处理比较,耕层(0—15 cm)全磷(TP)、有效磷(O lsen-P)和无机磷(I-P)含量均显著增加,有机磷(O-P)含量仅在MNP、MPK、MNPK和CPK处理中显著增加;耕层以下O-P无显著增加,MNPK、MNP、MRN和MN处理中I-P下移可达25 cm,而MNPK处理中TP及MNPK、CNP处理中O lsen-P下移可达30 cm;耕层磷素积累量及磷素下移深度与施磷量、施肥模式(化肥磷、有机肥磷;单施、混施)和磷素形态有关。(2)有机肥I-P下移深度比化肥I-P深。(3)不同施肥处理对水体环境存在不同的污染风险,其中以MNPK处理下土壤磷素对水体环境的污染风险最大;地表水的污染风险大于地下水,稻季的污染风险大于麦季,丰水年的污染风险大于平水年。     

有机酸对不同磷源条件下土壤无机磷形态的影响

土壤有效磷含量低是影响作物生产的重要限制因素之一.作物根分泌活化难溶性磷的有机酸对改善其磷素营养具有重要意义.采用张守敬和Jackson无机磷分级方法,以湖北省武昌土为材料,加入不同磷源和有机酸,经室温培养后,测定速效磷含量和无机磷组分.结果表明,有机酸引起速效磷含量增多,除苹果酸处理的变化较小外,草酸和柠檬酸的加入使土壤中速效磷显著增加.供试有机酸均使土壤铝磷(Al-P)含量下降,钙磷(Ca-P)含量上升,变幅大小依次为草酸处理>柠檬酸处理>苹果酸处理;有机酸活化的磷主要来源于土壤中Al-P和铁磷(Fe-P)中的磷,同时有机酸能够促进土壤中闭蓄态磷(O-P)的形成与积累.图1表3参30     

高产水稻氮钾施用量最佳配比研究

求导了水稻目标产量的预测方程,不同氮钾施用水平的等产方程,以及氮钾最佳配比方程。根据上述方程推导出地力产量为6345kg／hm2的水稻田目标产量为8589kg／hm2,N与K2O施用量的最佳配比为11．22,即N139．4kg／hm2、K2O170．6kg／hm2。     

黑磷纳米片应用及生物毒性研究进展

黑磷纳米片(black phosphorus nanosheet,BPNS)是一种新型纳米材料,它拥有可调节的带隙宽度、高度各向异性、高载流子迁移率、广谱光吸收性和良好生物相容性等诸多特性,在电子、光电、电化学、环保和生物医学等领域表现出巨大的应用潜力.近年来,随着对BPNS研究的深入,其生物安全性问题备受关注.本文简...     

不同母质砖红壤的磷有效性差异

不同母质的砖红壤,其磷素含量有差异;磷的有效性受土壤营养体系中其它元素的制约;桉树植株的磷营养受土壤有效磷含量和土壤营养体系中多种元素相互作用的影响。     

氮磷营养盐因子对缘管浒苔生长、叶绿素荧光特性和氮磷富集的影响

为探讨大型海藻缘管浒苔(Ulva linza)对氮、磷加富的生理响应及其机制,分析了氮、磷浓度变化对藻体相对生长速率(Rr.g),氮、磷富集,叶绿素(Chl)含量,类胡萝卜素(Car)含量,色素比值(Chl a/Chl b、Chl/Car)以及叶绿素荧光参数的影响.结果表明,在30μmol·L-1P浓度不变条件下,随着N浓度的增加,藻体P含量持续降低,而其Rr、g、N含量、Chl含量、Car含量、色素比值(Chl a/Chl b、Chl/Car)和叶绿素荧光参数均逐渐上升,N3处理(500μmol· L-1 N)缘管浒苔Rr.g和叶绿素荧光参数均达到最大值,N4处理(1 000 μmol·L-1)缘管浒苔Chl含量、Car含量和Chl a/Chl b比值均达到最大值.在500 μmol·L-1N浓度不变条件下,依次增加P浓度,缘管浒苔Rr,g没有显著差异,N含量没有显著变化,而P含量则呈明显上升趋势,其他指标变化幅度小.综上所述,与P相比,N的变化对缘管浒苔生长、光合色素和光合作用的影响更明显,在N浓度为500 μmol·L-1、P浓度为30 μmol ·L-1、N/P比值为16.67条件下,藻体生长最佳.当水体富营养化加剧时,缘管浒苔富集氮、磷的能力持续上升.     

The Role of Macrophytes in the Retention of Phosphorus in the River Thame,England

The effects of the growth of the dominant species of macrophytes on phosphorus transport in the River Thame, a nutrient enriched lowland clay catchment in southern England, were assessed using a mass-balance approach. Macrophyte abundance was estimated between late March and early June at three sites along the river. the plant biomass of phosphorus and the total phosphorus content of sediments in the main part of the river channel and sediments associated with the plant roots were measured on each occasion. Total phosphorus concentrations in the river water were measured at weekly intervals at a gauging station at the lower end of the study reach.

The results showed that the phosphorus content of plants at the site most impacted by sewage derived phosphorus was < 1% of the flux of total phosphorus estimated for the water column in April and May. Phosphorus contained in the total standing crop of macrophytes at the least impacted site was estimated as approximately 3% of the mean daily flux of total phosphorus in the water. Although no trends were found in the total phosphorus contents of the roots, shoots or sediments through the season, differences in the phosphorus content of the sediments were found between sites with different phosphorus loading. Higher porewater and Equilibrium Phosphate Concentrations (EPC_oS) were recorded at the site most impacted by sewage effluent when compared to an upstream sampling site.     

The Influence of Varying Planktonic and Periphytic Algal Biomass On Exposure to Polychlorinated Biphenyls in Mesocosms

Algal populations, either suspended in the water column (planktonic) or present on the walls of an enclosure (periphytic), develop differently depending upon the physical scale of the system. This study determined whether these variations altered the speciation and therefore exposure of polychlorinated biphenyls (PCBs) in estuarine mesocosms. Exposure was defined as the fraction of applied contaminant taken up by plankton after two hours. Using a three phase equilibrium model, the partitioning of a suite of PCBs within variously-sized mesocosms was predicted using laboratory derived distribution coefficients and measured levels of planktonic and periphytic algal biomass. in mesocosms having large wall surface area to volume ratios, sorption of hydrophobic PCBs to periphyton significantly decreased contaminant exposure. However, within the range of planktonic algal biomasses observed in this study, the regulation of PCB exposure was relatively invariant between variously-sized mesocosms. to minimize sorption of hydrophobic organic contaminants (HOCs) to periphyton and reduce artefacts inherent with this partitioning, we suggest using mesocosms with low wall surface area to volume ratios (less than or equal to 1). in addition, periphytic biomass should be quantified regularly and a three-phase equilibrium approach used to predict the actual exposure concentrations.     

热带胶园土壤磷素形态和生物有效性

采用Hedley的磷素分级方法研究热带胶园土壤磷的形态,结果表明、热带胶园土壤磷主要以ResidualP、NaOH－Po和NaOH－Pi形态存在;各种形态磷的损失质量分数均高于38％;其中ResidualP和NaOH－Po的损失量最高,分别占全磷损失量的52％和16％,它们是长期耕作条件下热带胶园土壤磷两种最重要的有效磷源。     

The Influence of Varying Planktonic and Periphytic Algal Biomass On Exposure to Polychlorinated Biphenyls in Mesocosms

Algal populations, either suspended in the water column (planktonic) or present on the walls of an enclosure (periphytic), develop differently depending upon the physical scale of the system. This study determined whether these variations altered the speciation and therefore exposure of polychlorinated biphenyls (PCBs) in estuarine mesocosms. Exposure was defined as the fraction of applied contaminant taken up by plankton after two hours. Using a three phase equilibrium model, the partitioning of a suite of PCBs within variously-sized mesocosms was predicted using laboratory derived distribution coefficients and measured levels of planktonic and periphytic algal biomass. in mesocosms having large wall surface area to volume ratios, sorption of hydrophobic PCBs to periphyton significantly decreased contaminant exposure. However, within the range of planktonic algal biomasses observed in this study, the regulation of PCB exposure was relatively invariant between variously-sized mesocosms. to minimize sorption of hydrophobic organic contaminants (HOCs) to periphyton and reduce artefacts inherent with this partitioning, we suggest using mesocosms with low wall surface area to volume ratios (less than or equal to 1). in addition, periphytic biomass should be quantified regularly and a three-phase equilibrium approach used to predict the actual exposure concentrations.