青海高原干旱地区小麦主栽品种田间化感作用评价

为探索以小麦和杂草共存的生态群落为基础的生态防控技术,采用田间小区自然生长的方法,对青海高原10个主栽小麦品种(系)的化感作用进行评价。通过计算各小麦品种(系)对田间主要杂草各项生长指标的抑制率、化感指数,综合评价各小麦品种(系)在田间的控草作用强弱。结果表明:各小麦品种对田间杂草总株数抑制率为23.67%~45.85%,鲜重抑制率为43.64%~76.23%,干重抑制率为34.19%~76.24%;10个品种(系)对田间优势杂草自生油菜(Brassica napus L.)和密花香薷(Elsholtziadensa Benth.)的化感指数(RI值)绝大多数为负值,说明10个品种(系)对田间优势杂草种群均表现出抑制作用,其中高原448号品种田间化感抑草作用最强。基于最远邻近距离法,将10个小麦品种(系)进行聚类分析得出:高原448号、阿勃化感抑草作用最强,高原437号、青春38号、乐麦5号、互麦14、互麦15号、通麦1号化感抑草作用中等,互助红和品系74化感抑草作用最差。     

青海高原地区春小麦品种田间化感作用评价

为明确青海高原地区不同春小麦品种对麦田主要危害杂草旱雀麦Bromus tectorum的化感作用,本研究通过田间一致性试 验对青海高原地区的20个春小麦品种(系)进行化感作用评价,筛选出强化感作用品种。分别于春小麦3～5叶期和成熟期调查受体旱雀麦的生长性状,转化为化感作用指数,并结合聚类分析,将20个小麦品种按化感作用的强弱分为强、中、弱３类。结果表明,20个春小麦品种(系)对受体旱雀麦的田间生长均具有化感抑制作用,其中‘青春38号’‘黑丝麦1号’‘通麦2号’和‘互麦11号’为田间化感作用较强的春小麦品种。该研究为青海高原地区春小麦化感抑草品种选育提供了新资源,同时为青海高原地区化学农药减量和生态环境保护提供了新策略。     

气候变暖背景下青海省春季干旱时空变化

基于1961-2018年35个气象台站观测资料,分析了青海省农牧区无雨日数、干旱次数时空演变特征,结果表明:①1961-2018年青海省春季平均气温呈升高趋势、降水呈增多趋势,无雨日数空间差异明显,其中,东部农业区、牧业区无雨日数总体无明显变化趋势。②近57 a,东部农业区轻旱、中旱、特旱发生次数均无明显趋势性变化,仅重旱略有增加,进入21世纪以来,东部农业区轻旱、重旱发生次数呈增加趋势,农业区各等级干旱次数呈南多北少的空间分布。③近57 a,青海省主要牧业区出现干旱总次数及不同等级干旱次数均呈减少趋势。其中,轻旱减少最为明显,而牧业区各等级干旱次数呈北多南少的分布。④青海省春季出现灾损的旱灾次数呈减少趋势,减少率为2.4次·(10a)^-1。其中,东部农业区出现灾损的旱灾次数最多。⑤近57 a青海省牧业区干旱发生次数在1981年前后存在明显的突变现象,而东部农业区无明显的突变现象。     

中国沙棘浸提液对其种子萌发的化感效应

为揭示中国沙棘的自化感效应,利用枝叶、表层土、果的浸提液对种子萌发进行了化感试验。结果表明:不同部位的浸提液及其不同浓度均对萌发产生显著或极显著的化感作用,且呈现出低促高抑的浓度效应,其中枝叶的化感作用最强,并对林下土壤产生显著的影响。     

旱直播稻抑草潜力的评价

利用旱直播稻自身的竞争及化感作用,评价旱直播稻品种（品系）对杂草的抑制作用。采用田间小区试验方法,评价旱直播稻对杂草的竞争能力和耐受能力。通过测定旱直播稻特征化感次生物质含量计算出的化感指数来评价其化感潜力;在旱直播稻播种后45 d,杂草生物量与旱直播稻的生物量成显著负相关、与相对竞争强度成显著的正相关。旱稻品系‘HF04’和‘HF011’对杂草的抑制作用最强,前者抑草能力强表现在竞争力,后者抑草能力强表现在耐受杂草竞争力和化感作用。     

芦苇提取物对5种植物的化感作用

采用培养皿滤纸法,测定了芦苇提取物对小麦、萝卜、黄瓜、稗草和反枝苋5种受体植物的化感作用。结果表明,在0. 08 g/mL浓度时,对除黄瓜外的受体植物种子萌发抑制率为69. 2%～75. 1%,EC50值分别为0. 044、0. 046、0. 033和0. 042 g/mL,对黄瓜种子萌发的抑制作用较差,抑制率为10. 6%。在0. 16 mg/L浓度时,对5种受体植物幼苗茎生长的抑制率为69. 3%～93. 2%,EC50值0. 042～0. 100 g/mL;对幼苗根生长的抑制率为75. 3%～97. 7%,EC50值0. 024～0. 079 g/mL。试验结果丰富了芦苇化感作用范围,从中可能发现新的除草活性化合物。     

春小麦品种“和尚头”的抗旱生理机制及评价

为探讨旱地春小麦"和尚头"的抗旱生理机制,以西北地区各生态区不同基因型春小麦品种宁春4号、高原448作对照,采用20%PEG-6000模拟渗透胁迫,研究幼苗叶片含水量、膜透性、游离脯氨酸及丙二醛含量等生理指标,并进行相关性及聚类分析。结果表明,不同品种对干旱胁迫的生理响应差异显著(P0.05)。"和尚头"表现出相对高的叶片含水量和脯氨酸含量、低的细胞膜损伤率和丙二醛含量,生理响应指标优于宁春4号和高原448。干旱胁迫48 h"和尚头"叶片含水量和脯氨酸含量分别为72.06%±0.41%和37.06±2.35μg·g-1,显著高于对照品种(P0.05);丙二醛含量为46.12±1.20μmol·g-1,显著低于对照品种(P0.05);电导率为70.11%±1.69%,显著低于对照品种高原448(P0.05),与宁春4号差异不显著(P0.05)。春小麦各生理响应指标间具有显著的相关性(P0.05),通过聚类分析实现了干旱胁迫条件下不同春小麦品种生理响应间差异。综合评价品种的抗旱性强弱依次为:"和尚头"宁春4号高原448。     

油菜对千金子的化感作用及其化感物质分离鉴定

研究了油菜茎根水提液对后茬稻田中恶性杂草千金子的化感作用,并分离鉴定了化感物质。结果表明,不同品种油菜的水提液对千金子种子萌发有抑制作用,对幼苗生长无影响,同时对水稻种子萌发及幼苗生长安全。利用室内生测及GC-MS方法鉴定抑制千金子种子萌发的化感物质为有机酸,抑制率达100%。其主要成分为油酸、棕榈酸、芥酸、亚油酸、硬脂酸、二十碳烯酸及山嵛酸。     

不同条件下韭菜汁对香蕉枯萎病菌4号小种活性抑制的研究

研究了不同温度、pH值、杀虫剂和杀菌剂的影响下,韭菜汁对香蕉枯萎病菌4号小种的抑制作用,以确定韭菜汁在不同条件影响下对病菌的活力。结果表明,在试验的各温度处理后,55℃以上的温度对韭菜汁的成分有破坏作用,菌落的生长受到显著影响。韭菜根汁对病菌孢子的抑制作用不受pH值的影响。酸性至弱碱性情况下,韭菜茎汁对病菌孢子萌发的抑制率为100%;在强碱性条件下,韭菜茎汁中物质的活性促进了孢子的萌发。供试杀虫剂和杀菌剂对韭菜汁的成分无明显破坏作用。     

甘薯不同品种对两种入侵杂草的竞争作用和化感作用

本研究通过盆栽试验和生物测定试验,分别研究了9个不同农艺性状的甘薯品种对三叶鬼针草Bidens pilosa和粗毛牛膝菊Galinsoga quadriradiata的竞争作用和化感作用。结果表明,‘烟薯25’‘宁薯10号’和‘西瓜红普薯’等6个品种的竞争平衡指数(CBa)大于0,其中‘宁薯10号’的竞争优势最强,对三叶鬼针草的株高和根长的抑制率分别为62.29%和63.31%;生物测定中仅有‘17234’和‘宁薯10号’两个品种表现出明显的化感作用,其中‘17234’的化感作用指数(AI)最大,对粗毛牛膝菊的株高和根长的抑制率分别为74.32%和82.58%。结合甘薯品种的竞争作用与化感作用进行聚类分析和综合评价,‘宁薯10号’的CBa和AI分别达0.74和0.63以上,为竞争作用和化感作用均较强的抗(耐)性品种;‘烟薯25’虽然对两种入侵杂草的CBa分别达到0.85和0.70,但其AI＜0.1,表现为具有竞争优势的非化感品种;尽管‘17234’的CBa＜0,但其AI＞0.67,说明其为强化感作用的品种。结果表明,甘薯对入侵杂草的抗(耐)性决定于其自身的竞争作用、化感作用或两者的共同作用。这为进一步利用甘薯不同品种对入侵杂草的种间关系实施替代控制提供了科学基础。     

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.