大气干湿沉降向城市系统输入重金属元素通量特征研究——以沈阳市为例

[目的]探讨大气干湿沉降向城市系统输入重金属元素通量特征.[方法]根据沈阳市不同行政区采样点重金属元素沉降通量,分析沈阳市不同行政区重金属大气干湿沉降污染的空间分布特征.[结果]在不同的采样点,大气干湿沉降中元素的年沉降通量差异较大,但其在沈阳市不同行政区分布规律大致相同.Cd、Pb、Hg的年沉降通量在各地区的分布分别表现为：铁西区＞皇姑区＞沈河区＞和平区＞大东区＞东陵（浑南）区＞于洪区,铁西区＞沈河区＞皇姑区＞和平区＞东陵区＞于洪区＞大东区＞浑南区,铁西区＞沈河区＞皇姑区＞和平区＞大东（东陵）区＞于洪（浑南）区.大气降尘污染的空间分布与污染源地域分布具有一致性,即工业区＞商业区或交通区＞文化区＞居民区＞郊区.[结论]该研究为大气干湿沉降污染的控制与治理提供了理论参考.     

药用植物连作障碍研究进展

中医是我国特有的传统文化和产业,优质中药材是关系国计民生的战略性资源.近年来随着国内外对中药材需求的日益增长,人工栽培药用植物的种类和面积大幅增加,由于耕地有限、种植条件及道地性等因素的限制,在药用植物集约化种植过程中,普遍存在严重的连作障碍问题,在以块根类入药的药用植物上表现尤为严重.目前连作障碍已经成为制约中药材产量和品质的关键因素,严重阻碍中药材规范化种植和产业化发展.从药用植物连作障碍危害、形成机理以及调控措施的最新研究进展进行总结,指出连作障碍问题主要是植物-土壤-微生物三者共同作用的结果,分析了当前药用植物连作障碍形成的3个主要原因,包括土壤养分亏缺和失衡、化感自毒作用以及根际微生态破坏导致土传病害加重.提出了连作障碍的调控措施,包括优良品系选育、土壤灭菌、建立合理的耕种制度、施用微生物菌肥,并对未来研究的方向和重点进行了探讨,以期为克服药用植物连作障碍的栽培管理提供科学参考.     

连作对云南典型烟区植烟土壤细菌群落多样性的影响

为阐明连作对植烟土壤细菌群落的影响,采用MiSeq高通量测序技术对云南省曲靖市、红河州、文山州3个典型烟区连作0、2、4、8年及以上的烟田土壤细菌进行16S rDNA V3～V4区域测序,并结合土壤化学指标分析连作对烟田土壤细菌群落结构的影响.结果 表明:随连作年限的延长,土壤特有细菌数、细菌群落丰度和多样性在曲靖烟区整体呈递增趋势,红河烟区呈递减趋势,文山烟区特有细菌数呈先下降后上升趋势,细菌群落丰度及多样性则呈递增趋势.在门水平上,3个生态产区连作土壤所获得的有效序列涵盖了94.32％～99.31％的细菌类群,放线菌门(Actinobacteria)、变形菌门(Protecobacteria)、绿弯菌门(Chloroflexi)、酸杆菌门(Acidobacteria)、芽单胞菌门(Gemmatimonadetes)、浮霉菌门(Planctomycetes)是主要的优势类群(相对丰度>4.0％),随连作年限的延长,不同生态区优势菌门相对丰度和多样性存在时间和空间异质性.连作植烟土壤pH值、速效钾、有机质、有效磷含量与细菌群落分布显著相关.研究表明,随着连作年限的延长,土壤细菌群落发生不同程度的结构性变化,在连作烟田土壤改良时加强土壤pH值和有效磷含量调控是关键.研究结果为云南典型烟区通过构建差异化的土壤微生物区系和理化环境以消减连作障碍提供了理论依据.     

强化栽培条件下干湿灌溉对水稻生长的影响

在中国水稻研究所试验场研究了强化栽培条件下干湿灌溉对水稻生长的影响.结果表明:在强化栽培条件下采取干湿灌溉处理,在返青期、分蘖期、孕穗期和抽穗开花期比对照分别节水1.4%、12.4%、9.0%和11.2%;水分生产效率达0.93 kg/m3,比CK处理提高34.2%;干4～5 d之后,再复水4～5 d,土壤氧化还原电位循环变化,有利于提高土壤氧化还原电位,改善土壤的通气状况,提高根系活力,促进大穗,穗粒致明显增加,单产平均提高6.9%.     

连续式真空干燥机在鱼粉加工中应用研究

研究了连续式真空干燥机在鱼粉加工中的工艺过程、工艺结构和工作原理。鱼粉加工中采用连续真空干燥机具有明显的优势,可以减少高温对鱼粉蛋白质的氧化,提高鱼粉蛋白质的含量,提升鱼粉品质,使其在市场竞争中占有优势。     

巴音郭楞蒙古自治州野生动物资源及其消长

依据新疆巴音郭楞蒙古自治州１９６５至１９９０年野生脊椎动物皮张产品的收购资料及历年实地考察研究，分析与分析了该地野生动物资源现状，利用价值，数量消长因素及有关管理措施等，该地区鸟类种数约２６４种，兽类７３种、两栖爬行类１０余种，鱼类２０多种。     

Potato plant response to seed tuber bacterization in the field in various rotations

The effects of a seed tuber treatment with antagonistic isolates of fluorescentPseudomonas spp. were investigated on potato plants from 1981 to 1984. The experimental plots were located in fields in short and long rotations of potato. The short rotations are characterized by serious yield reductions which are caused by unknown microbial factors. The reductions varied from 30% in 1982 to only 3% in 1983 in the 3-year rotations. A statistically significant increase in yield (four to five months after planting) of ware potatoes varying from 9 to 20% was obtained in these plots through tuber bacterization, but only in 1981. In 1982 and 1983 initially significant improvements in shoot or tuber weight of seed potatoes were no longer detectable at ware potato harvest at the end of the growing period. Seed tuber bacterization had no effect on tuber yield in long rotations. Initial colonization of basal root parts by 53×10⁴ colony forming units (cfu) of antibiotic-resistant mutants per gram of root (fresh) dropped significantly to 20×10⁴ cfu per gram after three months. The bacterization effect on tuber yield depended on the development of harmful microbial activity and of introduced antagonists during the growing period. Seed tuber bacterization is more promising for seed potatoes than for ware potatoes in short rotations, the latter being harvested two months later.Samenvatting De invloed van pootgoedbehandeling met antagonistische isolaten van fluorescerendePseudomonas-soorten op de aardappelteelt, werd onderzocht in de periode van 1981 tot en met 1984. De proefvelden maakten deel uit van zowel ruime als nauwe rotaties met aardappelen. Kenmerkend voor de nauwe rotatie is, dat de opbrengst aanzienllijk gereduceerd wordt als gevolg van de aanwezigheid van nog onbekende microbiële factoren. Deze opbrengstverlaging varieerde van 30% in 1982 tot slechts 3% in 1983 in de 3-jarige rotaties. Pootgoedbacterisatie had in deze proefvelden een significante toename van de eindopbrengst (vier tot vijf maanden na pootdatum) van consumptieaardappelen tot gevolg, die varieerde van 9 tot 20%, echter allen in 1981. In 1982 en 1983 werd het effect van bacterisatie ook in de loop van de groeiperiode onderzocht. Aanvankelijk significante toenames van zowel spruit-als knolgewicht waren aan het einde van het groeiseizoen niet meer aantoonbaar. Pootgoedbacteristie bleek geen effect te hebben op aardappel in ruimte rotaties. Aanvankelijk werden de basale wortelgedeelten gekoloniseerd door antibioticum-resistente mutanten met 53×10⁴ kolonievormende eenheden (kve) per gram wortel(vers); dit aantal liep (drie maanden na pootdatum) echter significant terug tot 20×10⁴ kve per gram. Het effect van bacterisatie op de eindopbrengst werd bepaald door de ontwikkeling van de schadelijke microbiële activiteit en de ontwikkeling van de geïntroduceerde antagonisten tijdens het groeiseizoen. Pootgoedbacterisatie in nauwe rotaties biedt meer mogelijkheden voor de teelt van pootaardappelen dan die van consumptieaardappelen, die geruime tijd later geoogst worden.     

Infection of Linseed by Alternaria linicola; Effects of Inoculum Density, Temperature, Leaf Wetness and Light Regime

Controlled environment studies were conducted to determine the effects of inoculum density, temperature, leaf wetness and light regime on the infection of linseed by Alternaria linicola. The % cotyledons and leaves with symptoms, and the disease severity (% leaf area with symptoms) increased linearly when the inoculum density increased from 1×10³ to 1×10⁵ conidiaml^–1. The first symptoms appeared on cotyledons and leaves 4 and 6 days after inoculation, respectively. Eight hours of leaf wetness were sufficient to initiate the disease at 25°C but not at 15°C, when 10-h periods of leaf wetness were required. % leaf area with symptoms was lower at 15°C than that at 25°C irrespective of the leaf wetness periods tested. Interruption of a continuous leaf wetness period by a 12-h dry period, occurring at any time between 1 and 18h after inoculation, decreased the % cotyledons with symptoms and the disease severity, with the greatest reductions (60% and 100%, respectively) being observed when the dry period began 6h after inoculation. A. linicola conidia were able to exploit successive 12-h periods of leaf wetness cumulatively to infect linseed plants. Disease incidence and severity were positively correlated with the dark period following inoculation, but they were negatively related to the length of the initial light period. Our findings suggest that infection of linseed by A. linicola and further development of symptoms can occur under unfavourable environmental conditions.     

Effects of amino nitrogen on fermentation parameters by mixed ruminal microbes when energy or nitrogen is limited

Ruminal microbes harvested from a ruminally fistulated cow were incubated in simple batch and semicontinuous cultures with NH₃‐N or amino‐N on nitrogen‐ or energy‐excess diets in quantity (HN and LN diets, respectively, consisting of timothy hay plus soybean meal, or corn grain), based on evaluation with the National Research Council and Cornell Net Carbohydrate and Protein System models. In a batch culture experiment, supplementation with amino‐N promoted digestion and fermentation in the course of incubation (4–24 h) on both diets, but these effects mostly disappeared when the diets were sufficiently digested (at 48 h). In a semicontinuous culture experiment using Rusitec, no effect of amino‐N was exhibited after sufficient fermentation and digestion, but significant promotion of digestion was shown in the course of incubation on the HN diet, while no such effect was detected on the LN diet. The microbial yield for 24 h did not show a significant difference between the N sources of either of the two diets. These results suggest that the stimulatory effects of amino‐N are diminished when the diets are sufficiently digested after a long retention and incubation, and also that the effectiveness of amino‐N does not require a quantitatively energy‐excess status.     

Can the occurrence of Senecio jacobaea be influenced by management practice?

Senecio jacobaea is a poisonous weed in grasslands of various countries (e.g. Great Britain, New Zealand, Central European states) and the further spread of the species into farmland must be prevented. To assess the influence of management practice and site conditions on the occurrence of S. jacobaea, we conducted a survey in the northern and central part of Switzerland. Botanical assessments were carried out on grassland plots with S. jacobaea occurrence and on neighbour plots without S. jacobaea. For these plots, we analysed the soil nutrients and the details of management practice, such as type and intensity of management and fertiliser application. The most important factors influencing the occurrence of S. jacobaea were related to management: There was a high risk for the occurrence of the species on parcels with low nitrogen fertilisation, continuous‐extensive grazing (set stocking) and a very open sward. Senecio jacobaea was not present in intensively managed meadows cut more than twice per year. As an exception, with a high propagule pressure from the vicinity, S. jacobaea was also found in intensively grazed pastures and in meadows of moderate management intensity (two cuts). We conclude that long‐term control of S. jacobaea can best be achieved by avoiding sward damage and by preventing the species’ seed formation in the pasture and local vicinity.