紫茎泽兰化感作用的研究进展

为能更有效地防治和利用紫茎泽兰.国内进行了广泛、深入的研究.其中对紫茎泽兰化感作用的研究较多,针对紫茎泽兰的化学成分及其提取物对植物、动物和菌类化感作用的研究进展,笔者进行了论述,并探讨了研究中存在的问题.     

紫茎泽兰的生态学研究概况

紫茎泽兰是一种生长迅速、繁殖率高、能排挤本土物种形成单优群落的外来物种,同时能使入侵地的生物多样性丧失、严重破坏当地的生态系统.通过对紫茎泽兰生长的生物学特性、营养、环境、需光特性以及紫茎泽兰的种子库和化感作用等的阐述,旨在为同行学者对紫茎泽兰的进一步研究提供可借鉴的依据.     

紫茎泽兰五种挥发性物质对木霉和灰霉的化感作用

紫茎泽兰Eupatorium adenophorum Spreng是一种世界性恶性入侵杂草[1-2],化感作用是其种群竞争扩张的重要策略[3].次生物质通过器官表面的挥发是化感物质释放的主要途径之一,3-己烯-1-醇、水芹烯、2-蒈烯、α-蒎烯、莰烯是紫茎泽兰的挥发性化感组分[4-5].植物挥发物不仅影响本地植物的生长,而且也影响微生物的生长和发育.为从微生物学的角度进一步探讨紫茎泽兰的入侵机制,本试验以木霉Trichoderma harzianum和灰霉Botrytis cinerea为研究对象,研究了紫茎泽兰的5种挥发物对木霉和灰霉孢子萌发和菌丝生长的影响.     

紫茎泽兰化感作用研究

有紫茎泽兰生长与无紫茎泽兰生长的土壤中,一年生黑麦草、多年生黑麦草、紫花苜蓿和光叶紫花苕的出苗率、株高和鲜重均无显著性差异;紫茎泽兰水培液与清水比较,无论是盆栽还是培养皿生长试验,4种牧草的成活率、株高和鲜重无显著性差异。由此得出：紫茎泽兰对4种牧草的生长无明显的化感作用。     

四川乐山地区紫茎泽兰的入侵定殖和风险评估

本文报道了四川省乐山地区犍为县塘坝乡境内入侵新物种一紫茎泽兰的分布、发生和定殖入侵情况。结合紫茎泽兰的生物学特性和当地的地理气候特征，对紫茎泽兰入侵乐山及其近邻地区的风险进行评估。     

混种牧草对紫茎泽兰根际土壤微生物的影响

外来入侵植物与入侵地土壤微生物群落之间的互作关系,影响外来植物的入侵力和生态系统的抵御功能。在紫茎泽兰入侵区利用非洲狗尾草进行替代控制,测量紫茎泽兰根际土壤微生物的变化结果显示,混种区根际土壤微生物之间及其与紫茎泽兰生物量之间的相关性较入侵对照区显著增强(P0.05),表明混种非洲狗尾草可加强紫茎泽兰入侵区根际土壤微生物的互利共生关系,有利于土壤微生物多样性的改善,可明显降低紫茎泽兰的生长势。     

入侵植物紫茎泽兰的防除技术

紫茎泽兰是入侵我国的恶性杂草,重庆市多个区县均有发生,严重为害农业、林业、畜牧业以及生态环境安全。在未大面积发生的情况下,应尽早清除。该文探讨了紫茎泽兰的为害、识别特征以及防除技术,以期为紫茎泽兰的防除提供帮助。     

紫茎泽兰淋溶主效化感物质对旱稻幼苗根尖解剖结构的影响

采用营养液培养法和石蜡切片技术,研究了紫茎泽兰淋溶主效化感物质（泽兰二酮和羟基泽兰酮）对旱稻幼苗根尖解剖结构的影响。结果表明：两个化感物质分别处理后,旱稻幼苗的根呈现短小肿胀、侧根缺乏、且对营养液的吸收明显减少,这些症状随着化感物质浓度的增加而加剧。石蜡切片的结果表明,和对照相比,化感物质处理后的旱稻幼苗根尖的解剖结构发生了明显的变化,主要表现在顶端分生组织、静止中心和根冠的细胞排列混乱,细胞间隙加大,皮层薄壁组织细胞变得短而粗,以及表皮层细胞大量脱落等。讨论认为,旱稻幼苗根的形态结构变化,主要与紫茎泽兰化感物质对受体植物吲哚乙酸的干扰相关。     

紫茎泽兰在不同群落中的生长与繁殖特征

为探讨不同生境条件下紫茎泽兰的生态对策,采用样方法对广西野外4个不同群落中紫茎泽兰的生长和繁殖特征进行调查研究。结果表明,野外不同群落之间紫茎泽兰的生长与繁殖特征大多存在显著差异,除株高外,其他参数都是开阔地最高,白栎黄檀混交林最低。不同群落之间紫茎泽兰的地上生物量以及繁殖分配存在显著差异,开阔地和桉树林中紫茎泽兰的地上生物量显著大于其他2个群落;开阔地中紫茎泽兰繁殖分配最大,显著大于其他群落。群落的郁闭度与紫茎泽兰的各生长和繁殖参数都呈极显著负相关关系,说明群落郁闭度影响紫茎泽兰的生长与繁殖。紫茎泽兰能根据不同的环境变化选择不同的适应对策,说明紫茎泽兰具有很强的适应能力,容易入侵到各个生境中。郁闭度较高的群落对紫茎泽兰有较好的控制作用,因而进行群落改造、增加群落的郁闭度,能有效地控制紫茎泽兰。     

中国重要外来物种紫茎泽兰的研究现状

紫茎泽兰曾被作为观赏性植物引入欧洲、澳洲、南美洲、亚洲等地,如今却成为我国最具侵害性的杂草之一。本文综述了外来恶性杂草紫茎泽兰的植物学特征、分布、入侵机制、危害性,以及对它的防除与综合利用。     

Richtlinien der Verbände des ökologischen Landbaus zum Vorratsschutz

Zusammenfassung Verbände des ökologischen Landbaus wie z. B. Bioland, Gäa, Demeter; Naturland, Ernte für das Leben oder Bio Suisse beschränken ihre Mitglieder bei der Wahl von Vorratsschutzmaßnahmen. Vorrang besitzen Maßnahmen zur Vermeidung von Schädlingen gegenüber Bekämpfungsmaßnahmen. Fallen müssen zur Befallsüberwachung eingesetzt werden, um einen Befall durch Vorratsschädlinge frühzeitig zu erkennen. Diese Maßnahmen sollen den weitgehenden Verzicht auf chemisch-synthetische Mittel ermöglichen. In diesem Beitrag werden die Empfehlungen der Verbände mit den derzeit verfügbaren chemischen Mitteln für den Vorratsschutz abgeglichen. Erfahrung in der praktischen Umsetzung von physikalischen und biologischen Verfahren werden diskutiert und Defizite bei der Befallsüberwachung und Bekämpfung beschrieben.     

Development of protocols for detection of Colletotrichum acutatum and monitoring of strawberry anthracnose using real-time PCR

Real-time PCR (TaqMan®) assays were developed for the specific detection and discrimination of Colletotrichum spp., C. acutatum and C. gloeosporioides causing anthracnose in strawberry using the most divergent area of the internal transcribed spacers (ITS1 and ITS2) and 5·8S ribosomal RNA (rRNA) gene region. The specificity of the new assays was tested using DNA from six species of Colletotrichum and nine fungal species commonly found associated with strawberry material, and additionally by comparing the sequences with those from databases using a blast search. The sequences only showed identity with homologous sequences from the desired target organisms. The new assays were 10–100 times more sensitive than conventional PCR methods previously published for the diagnosis of strawberry anthracnose. When real-time PCR was compared with ELISA methods, PCR improved the sensitivity of the identification by obtaining positive results for samples of strawberry plant material that tested negative with ELISA. The development of C. acutatum was monitored using artificially infected strawberry crowns from two strawberry cultivars (Camarosa and Ventana) and a real-time PCR assay specific for this species between January and June 2006. The amount of C. acutatum detected using real-time PCR varied significantly by month ( P  < 0·001), but not by cultivar ( P  = 0·394). The new assays were shown to be useful tools for rapid detection and identification of these pathogens and to allow rapid and accurate assessment of the casual agents of anthracnose in strawberry.     

A systematic review of the literature reveals trends and gaps in integrated pest management studies conducted in the United States

Integrated pest management (IPM) is a broad‐based approach for addressing pests that negatively affect human and environmental health and economic profitability. Weeds, insects and disease‐causing pathogens (diseases) are the pests most often associated with IPM. A systematic review, widely used in other scientific disciplines, was employed to determine the most commonly studied IPM topics and summarize the reasons for these trends and the gaps. In a field synopsis of the literature, 1679 relevant published papers were identified and categorized into one of the following five broad areas: IPM and organic (organic), climate change and pests (climate), rural and urban IPM (rural and urban), next‐generation education (education) and advanced production systems (technology). Papers were examined in greater detail for at least one of the three main pests in a systematic review. A majority (85%) of IPM papers have been in the area of rural and urban IPM, primarily addressing agriculture (78%). Professionals, landowners and the general public were the focus of a majority (95%) of IPM papers on education. Technology is an increasing area of focus in the literature. Over the past 40 years, IPM papers have primarily (75%) addressed insects and been limited mostly to rural and urban settings. Climate change, technology and education specific to pest management studies are increasingly being published and will help broaden the focus that could result in increased adoption and development of IPM. © 2017 Society of Chemical Industry     

Thermal and hormonal regulation of the dormancy–germination transition in Amaranthus tuberculatus seeds

The transition from seed dormancy to germination is a multi‐step process. However, distinguishing between physiological processes involved in seed dormancy alleviation and those involved in germination has been difficult. We studied the seed dormancy alleviation process in Amaranthus tuberculatus, an important weed species in midwestern USA. Using three A. tuberculatus biotypes that differ in dormancy level, it was determined that stratification reduced seed dormancy from a high to a low level. Temperature alternation alleviated low seed dormancy and triggered germination. Exogenously applied abscisic acid (ABA) and gibberellic acid (GA) had no effect on seeds with high dormancy. However, ABA and paclobutrazol (a GA biosynthesis inhibitor) significantly reduced germination of seeds with low dormancy. Hormones could not replace the effects of stratification or temperature alternation on dormancy alleviation. Based on our results, we propose a seed dormancy–germination transition model in which the dormancy of A. tuberculatus seeds is progressively reduced from a high to a low level; but environmental conditions (i.e. stratification) can accelerate the dormancy alleviation process. Under low dormancy levels, the seed is more sensitive to environmental cues that are responsible for removing dormancy and triggering germination (i.e. temperature alternation). Finally, ABA and GA regulation occurs primarily during the final transition from low dormancy to germination rather than the alleviation of high dormancy.     

Description ofPauesia (Pauesia)anatolica (Hymenoptera: Braconidae, Aphidiinae) sp. nov., a parasitoid of the cedar aphidCinara cedri

The first parasitoid species reared from a population of the cedar aphid,Cinara cedri Mimeur, 1935 (Hemiptera: Aphididae), from the peninsula of Anatolia in Turkey is described.Pauesia anatolica (Hymenoptera: Braconidae, Aphidiinae) is closely related to some species of thelaricis group ofPauesia from which it differs in the number of antenomers, the propodeum and features of the female genitalia. Its potential use as a natural enemy in areas where the aphid has been introduced is discussed. http://www.phytoparasitica.org posting Aug. 28, 2005.     

Current statistical issues in Weed Research

The correct design of experimental studies, the selection of the appropriate statistical analysis of data and the efficient presentation of results are key to the good conduct and communication of science. The last Guidance for the use and presentation of statistics in Weed Research was published in 1988. Since then, there have been developments in both the scope of research covered by the journal and in the statistical techniques available. This paper addresses the changes in statistics and provides a reference work that will aid researchers in the design and analysis of their work. It will also provide guidance for editors and reviewers. The paper is organised into sections, which will aid the selection of relevant paragraphs, as we recognise that particular approaches require particular statistical analysis. It also uses examples, questions and checklists, so that non-specialists can work towards the correct approach. Statistics can be complex, so knowing when to seek specialist advice is important. The structure and layout of this contribution should help weed scientists, but it cannot provide a comprehensive guide to every technique. Therefore, we provide references to further reading. We would like to reinforce the idea that statistical methods are not a set of recipes whose mindless application is required by convention; each experiment or study may involve subtleties that these guidelines cannot cover. Nevertheless, we anticipate that this paper will help weed scientists in their initial designs for research, in the analysis of data and in the presentation of results for publication.     

Electrophoretic and serological comparisons of pathogenesis-related (b) proteins from different plant species

Preparations of pathogenesis-related (b) proteins (PRs) from differentNicotiana species, tomato,Gynura aurantiaca, bean, and cowpea were compared to each other and to bean chitinase and a constitutive apple agglutinin by electrophoresis in polyacrylamide gels both in the absence and in the presence of SDS, and by serological double diffusion analysis using antisera against tobacco PRs and bean chitinase. PRs from different plant genera displayed a similar but not identical range of relative mobilities in both native and SDS gels, whereas bean chitinase and apple agglutinin were clearly different. None of the antisera reacted with any of the PR preparations from plant genera other than the one from which the antigen(s) had been derived. Whilst PRs within the genusNicotiana are serologically related and can be identical, PRs from different plant genera seem to be sufficiently different to be considered as genus-specific.     

Contribution of Biological Control to Integrated Pest Management of Tephritid Fruit Flies in the Tropics and Subtropics

The biological control of pest tephritid flies using parasitoids has been successful in relatively few subtropical and tropical regions. The best documented successes were in Hawaii and Florida, USA, Fiji and southern Europe. There were relatively limited successes in Australia, Costa Rica and Mexico. With the accidental establishment of new pest tephritids, such as Bactrocera latifrons (Hendel) in Hawaii or Bactrocera papayae Drew and Hancock in Australia, foreign exploration for new parasitoids is essential. A renewal of interest in classical biological control has recently occurred, although not at the same level as in the 1940s and 1950s. New parasitoid species are currently being obtained for several tephritids, such as Ceratitis capitata (Weidemann), B. latifrons and Anastrepha suspensa (Loew). The advances in mass rearing and quality control technology for parasitoids has enabled researchers to perform large-scale field testing of these parasitoids to determine the potential of augmentative releases. Numerous studies on the augmentative release of parasitoids have been done. Historically, the larval—pupal parasitoid Diachasmimorpha longicaudata (Ashmead) has been the most frequently studied parasitoid, due to the ease of rearing this species. However, recent successes in rearing other species with different biologies, e.g. the egg—pupal parasitoid Biosteres arisanus (Sonan), the gregarious eulophid, Tetrastichus giffardianus (Silvestri) and the pupal parasitoid, Coptera sp., will enable researchers to broaden the repertoire of parasitoid species for the future. Both successes and failures in augmentative releases have occurred. Without knowledge of the behavioural ecology of parasitoids, the reasons for success or failure can only be surmised. Recent research on the dispersal and host habitat finding of tephritid parasitoids will provide insights into improving augmentation and conservation strategies. The integrated pest management (IPM) of tephritid flies in the tropics has been less well-developed than research and programmes for tephritids in temperate zones. Significant emphasis is now being placed on the development of quarantine treatment methods that are environmentally sound; thus IPM will take a larger role. Several existing pest management strategies are reviewed which show the potential for compatibility with the activities of tephritid parasitoids. These include trap cropping, insecticides with selective toxicity to the target pests, mass trapping with parapheromones, the sterile insect technique and field sanitation.     

Rapid Identification of Clavibacter michiganensis Subspecies sepedonicus Using Two Primers Random Amplified Polymorphic DNA (TP-RAPD) Fingerprints

Twenty strains of Clavibacter michiganensis subsp. sepedonicus from different geographic origins and other reference strains of the same and different species, including other potato pathogens, were analysed with a new procedure named TP-RAPD that originates fingerprints of bacterial species. This procedure uses two primers to amplify the 16S rDNA gene. At 45 °C of annealing, the PCR product electrophoresed in agarose gels produced a band pattern that was different in all bacterial species studied as well as in the subspecies of C. michiganensis. All strains of C. michiganensis subsp. sepedonicus displayed the same TP-RAPD number of pattern. Unlike Gram negative bacteria, Gram positives of high G + C content, such as Clavibacter, produced low bands in TP-RAPD. By using a different set of two primers also based in the 16S rDNA sequence from Escherichia coli a more adequate amplification of Gram positives of high G + C including a greater number of bands was obtained. TP-RAPD patterns using the new set of primers described in this work is a reliable and fast method to identify C. michiganensis subsp. sepedonicus.