土壤质地对柱花草生长发育、生物量及土壤肥力变化的影响   总被引：1，自引：0，他引：1  

龙会英  张德  金杰 《土壤》2017,49(5):1049-1052

采用大田试验的方法,在云南省元谋县小雷宰流域内壤土、砂壤土和重壤土3种质地土壤上,以热研5号柱花草为材料,研究土壤质地对柱花草生长发育、生物量及土壤有机质、有机碳、全氮和全磷的影响。试验结果表明:3种土壤质地上种植柱花草,柱花草地上部和地下部生长量和生物量表现幼苗期增加缓慢,而分枝期后增加快的趋势。壤土耕性好,兼有砂土和重壤土的优点,有利柱花草地上部分的生长发育,柱花草地上部生长量、生物量及改善土壤肥力方面显著高于重壤土。砂壤土有利于柱花草根系向深层土壤生长,柱花草地下部生长量、生物量及根瘤显著高于种植在重壤土。在3种土壤质地种植柱花草后,土壤有机质、有机碳、全氮和全磷均有上升趋势。综合而言,通气性和保肥保水能力居中的壤土更适合柱花草的生长发育及干物质的积累。  相似文献   

风电机组尾流与疲劳载荷关系分析   总被引：3，自引：3，他引：0  

邓英  李嘉楠  刘河生  庞辉庆  田德 《农业工程学报》2017,33(10):239-244

为了研究风电机组尾流对下游风电机组载荷的影响,假设了几个重要尾流参数:上下游风电机组间距、上游风电机组推力系数、湍流强度等。采用Bladed软件和Matlab幅频程序,分别对1.5与3.0 MW双馈式风电机组进行各参数与载荷响应的关系计算。结果表明:风轮处风速会随着推力系数的增大非线性减小;风电机组处于尾流影响范围内时,在风速和推力系数相同的条件下,通常湍流强度受尾流影响后减小使载荷增大,但当推力系数对载荷的影响起主导作用时,虽然湍流强度受尾流影响后减小但载荷会增大;当风速大于额定风速时,应采用变桨控制减小推力系数,以减小风电机组的疲劳损伤。  相似文献   

Pharmacokinetic and pharmacodynamic evaluations of a 10 mg/kg enrofloxacin intramuscular administration in bearded dragons (Pogona vitticeps): a preliminary assessment          下载免费PDF全文

M. Salvadori  C. Vercelli  V. De Vito  D. Dezzutto  S. Bergagna  G. Re  M. Giorgi 《Journal of veterinary pharmacology and therapeutics》2017,40(1):62-69

Enrofloxacin (E) is commonly used in veterinary medicine. It is necessary to perform pharmacokinetic/dynamic studies to minimize the selection of resistant mutants of bacteria and extend the efficacy of antimicrobial agents. Eight healthy adult Pogona vitticeps were assigned into two groups of equal size and treated with a single intramuscular injection of E at 10 mg/kg. Blood samples were withdrawn at different scheduled times for each group, and rectal swabs were collected. E and ciprofloxacin (active metabolite) blood concentrations were quantified by an HPLC validated method, while the in vitro antimicrobial susceptibility was evaluated by the Kirby–Bauer disc diffusion susceptibility test. The pharmacokinetic profiles of E gave similar pharmacokinetic parameters irrespective of the collection time schedule. Bacteria isolation showed the presence of both E. coli, Salmonella enterica subspecies enterica and subspecies 3a, Proteus spp., and Pseudomonas spp. The majority of isolated colonies were sensitive to E, but the treatment did not reduce the number of bacteria in faeces. Results suggest that E is able to reach blood concentrations high enough to kill susceptible bacteria (MIC < 0.9 μg/mL), but at the same time does not significantly affect intestinal bacteria.  相似文献   

Characterization of Passionfruit severe leaf distortion virus,a novel begomovirus infecting passionfruit in Brazil,reveals a close relationship with tomato‐infecting begomoviruses     

S. S. Ferreira  D. R. Barros  M. R. De Almeida  F. M. Zerbini 《Plant pathology》2010,59(2):221-230

Molecular and biological characterization of the begomovirus isolate BR:LNS2:Pas:01, obtained from yellow passionfruit plants in Livramento de Nossa Senhora, Bahia state, Brazil, was carried out. Sequence analysis demonstrated that the BR:LNS2:Pas:01 DNA‐A had highest nucleotide sequence identity with Tomato chlorotic mottle virus (77%) and had five ORFs corresponding to the genes cp, rep, trap, ren and ac4. The DNA‐B had highest nucleotide sequence identity with Tomato yellow spot virus (74%) and two ORFs corresponding to the genes mp and nsp. These identity values indicate that this isolate represents a new begomovirus species, for which the name Passionfruit severe leaf distortion virus (PSLDV), is proposed. Phylogenetic analysis clustered the PSLDV DNA‐A and ‐B in a monophyletic branch with Brazilian tomato‐infecting begomoviruses. The isolate’s host range was restricted to species from the Passifloraceae and Solanaceae. PSLDV‐[BR:LNS2:Pas:01] was capable of forming pseudorecombinants with tomato‐infecting begomoviruses, reinforcing its close relationship with these viruses and suggesting a possible common origin. However, the virus was not capable of infecting tomato.  相似文献   

Effect of host factors on the susceptibility of Rhododendron to Phytophthora ramorum     

I. De Dobbelaere  A. Vercauteren  N. Speybroeck  D. Berkvens  E. Van Bockstaele  M. Maes  K. Heungens 《Plant pathology》2010,59(2):301-312

Phytophthora ramorum causes sudden oak death (SOD) in western coastal forests of the USA. In Europe, the pathogen is mainly present in the nursery industry, particularly on Rhododendron. Because of the primary role of Rhododendron as a host and potentially as a vector, the effect of Rhododendron host factors on P. ramorum susceptibility and sporulation was investigated. Inoculation methods using either wounded or non‐wounded detached leaves were applied to 59 Rhododendron cultivars and 22 botanical species, replicated in three separate years. All Rhododendron species and cultivars were susceptible when using wounded leaves, but not when using non‐wounded leaves, suggesting a resistance mechanism operating at the level of leaf penetration. Using a regression tree analysis, the cultivars and species were split into four susceptibility classes. Young leaves were more susceptible than mature leaves when wounded, but less susceptible when non‐wounded. This effect was not correlated with leaf hydrophobicity or the number of leaf hairs. The presence or the type of rootstock did not affect the cultivar susceptibility level. Sporangia and chlamydospore production in the leaf lesions varied widely among Rhododendron cultivars and was not correlated with the susceptibility level. The susceptibility to P. ramorum correlated well with the susceptibility to P. citricola and P. hedraiandra × cactorum, suggesting that the resistance mechanisms against these species are non‐specific. Susceptibility to P. kernoviae was low for most cultivars. These findings have implications for detection, spread and disease control, and are therefore important in pest risk assessment.  相似文献   

Detection of Ralstonia solanacearum (biovar 2A) in stems of symptomless plants before harvest of the potato crop using post-enrichment DAS-ELISA     

S. Priou  L. Gutarra  P. Aley  F. De Mendiburu  R. Llique 《Plant pathology》2010,59(1):59-67

The detection of Ralstonia solanacearum (biovar 2A) in stems of symptomless plants before harvest of the potato crop, instead of tubers, would not only save highly valued planting material but would be less time-consuming and would also enhance farmers' market decisions. Although pathogen detection in stems has been proven efficient for ring rot, this has never been investigated for bacterial wilt (BW). Therefore the possibility of detecting BW latent infection in stem pieces about three weeks before harvest was assessed in 57 fields of the Andean highlands of Peru. Two sensitive, specific and user-friendly serological methods were used to detect the pathogen in latently infected tubers and stems: double-antibody sandwich (DAS)-ELISA and indirect ELISA on nitrocellulose membrane (NCM) after enrichment of the plant extracts in a semi-specific broth. Optimum sample sizes of stems and tubers were evaluated for 37 potato crops showing between 0 and 0·1% BW incidence using a binomial distribution model to calculate the detection probabilities. Although results of detection using the two serological techniques had 100% concordance, detection probabilities were higher using DAS-ELISA, whatever the plant part tested. BW detection probabilities were higher for tubers than for stems; a 99% detection probability was obtained by analysing 400 stems sections or 250 tubers using DAS-ELISA. Detection of BW infection in symptomless plants 20 days before harvest using post-enrichment DAS-ELISA is a reliable and user-friendly technique that can easily be used by national plant protection services and seed programmes in developing countries.  相似文献   

Genetic diversity of the root‐knot nematode Meloidogyne enterolobii and development of a SCAR marker for this guava‐damaging species     

M. Tigano  K. De Siqueira  P. Castagnone‐Sereno  K. Mulet  P. Queiroz  M. Dos Santos  C. Teixeira  M. Almeida  J. Silva  R. Carneiro 《Plant pathology》2010,59(6):1054-1061

The objectives of this work were to evaluate the genetic variability of Meloidogyne enterolobii by molecular markers, and develop species‐specific molecular markers for application in detection. Sixteen M. enterolobii isolates from different geographical regions (Brazil and other countries) and hosts were used in this study. The identification and purification of the populations were carried out based on isoenzyme phenotype. The DNA amplification of the intergenic region (IGS) of the rDNA and of the region between the cytochrome oxidase subunit II (COII) and 16S rRNA genes (mtDNA) produced specific fragments of the expected size for this nematode, i.e. 780 and 705 bp, respectively. Intraspecific variability among the isolates was evaluated with three different neutral molecular markers: AFLP, ISSR and RAPD. The results showed a low level of diversity among the isolates tested, indicating that M. enterolobii is a genetically homogeneous root‐knot nematode species. The RAPD method allowed the identification of a species‐specific RAPD fragment for M. enterolobii. This fragment was cloned and sequenced, and from the sequence obtained, a set of primers was designed and tested. The amplification of a 520‐bp‐long fragment occurred only for the 16 isolates of M. enterolobii and not for the 10 other Meloidogyne species tested. In addition, positive detection was achieved in a single individual female, egg‐mass and second stage juvenile of this nematode. This SCAR species‐specific marker for M. enterolobii represents a new molecular tool to be used in the detection of this nematode from field samples and as a routine diagnostic test for quarantine devices .  相似文献   

Bacterial pathogens of rice in the Kingdom of Cambodia and description of a new pathogen causing a serious sheath rot disease     

E. J. Cother  D. H. Noble  R. J. Van De Ven  V. Lanoiselet  G. Ash  N. Vuthy  P. Visarto  B. Stodart 《Plant pathology》2010,59(5):944-953

A study of rice diseases in Cambodia from 2005 to 2007 showed widespread occurrence of diseases caused by Acidovorax avenae subsp. avenae, Burkholderia gladioli, B. cepacia and Pantoea ananatis. This is the first report of these pathogens in Cambodia. Additionally, a pseudomonad causing a widespread disease similar to sheath brown rot (caused by Pseudomonas fuscovaginae) was isolated. The studied strains were pathogenic to rice cvs Sen Pidau and IR 66, producing similar, though slightly less severe, symptoms to those observed in the field. Based on comparative 16S rDNA gene sequence analysis, combined with cell wall fatty acid analysis and metabolic profiles, the isolated strains were allocated to the genus Pseudomonas. The novel species were differentiated from Pseudomonas fuscovaginae and P. putida by their inability to metabolize d ‐fructose, d ‐galactose, d ‐galactonic acid lactone, d ‐galacturonic acid, d ‐glucosaminic acid, d ‐glucuronic acid, p‐hydroxy phenylacetic acid, d ‐saccharic acid and urocanic acid. The major fatty acids were C_16:0, summed feature 3 (C_16:1ω7c and C_16:1ω6c) and summed feature 8 (C_18:1ω7c), representing 80% of the total. Partial 16S rRNA gene sequences (1460 bp) were identical, except for two nucleotide changes amongst the six strains. Alignment of the causal strains within type‐culture databases revealed similarities of 99·7% with Pseudomonas parafulva AJ 2129^T, 99·2% with P. fulva IAM 1592^T, 98·9% with P. plecoglossicidia FPC 951^T, and 98·1% with P. fuscovaginae MAFF 301177^T. On the basis of data from this polyphasic study, it is proposed that the unknown strains isolated from rice represent a novel species of the genus Pseudomonas.  相似文献   

Selection,characterization and genetic analysis of laboratory mutants of <Emphasis Type="Italic">Botryotinia fuckeliana</Emphasis> (<Emphasis Type="Italic">Botrytis cinerea</Emphasis>) resistant to the fungicide boscalid     

Rita M. De Miccolis Angelini  Wassim Habib  Caterina Rotolo  Stefania Pollastro  Francesco Faretra 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(2):185-199

Resistance to the fungicide boscalid in laboratory mutants of Botryotinia fuckeliana (Botrytis cinerea) was investigated. The baseline sensitivity to boscalid was evaluated in terms of colony growth (EC₅₀ = 0.3–3 μg ml⁻¹; MIC = 10–30 μg ml⁻¹) and conidial germination (EC₅₀ = 0.03–0.1 μg ml⁻¹; MIC = 1–3 μg ml⁻¹) tests. Mutants were selected in vitro from wild-type strains of the fungus on a fungicide-amended medium containing acetate as a carbon source. Mutants showed two different levels of resistance to boscalid, distinguishable through the conidial germination tests: low (EC₅₀ ∼ 0.3 μg ml⁻¹, ranging from 0.03 to 1 μg ml⁻¹; MIC > 100 μg ml⁻¹) and high (EC₅₀ > 100 μg ml⁻¹) resistance. Analysis of meiotic progeny from crosses between resistant mutants and sensitive reference strains showed that resistant phenotypes were due to mutations in single major gene(s) inherited in a Mendelian fashion, and linked with both the Daf1 and Mbc1 genes, responsible for resistance to dicarboximide and benzimidazole fungicides, respectively. Gene sequence analysis of the four sub-units of the boscalid-target protein, the succinate dehydrogenase enzyme, revealed that single or double point mutations in the highly conserved regions of the iron-sulphur protein (Ip) gene were associated with resistance. Mutations resulted in proline to leucine or phenylalanine replacements at position 225 (P225L or P225F) in high resistant mutants, and in a histidine to tyrosine replacement at position 272 (H272Y) in low resistant mutants. Sequences of the flavoprotein and the two transmembrane sub-units of succinate dehydrogenase were never affected.  相似文献   

Molecular characterization of <Emphasis Type="Italic">Xiphinema brevicollum</Emphasis> (Nematoda: Longidoridae) from the Czech Republic     

Shesh Kumari  Wilfrida Decraemer  Francesca De Luca 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(2):243-250

Populations of Xiphinema brevicollum occurring in the Czech Republic were described morphologically and molecularly. Published species-specific primer set BL18 and BV3 was used to amplify three populations of X. brevicollum from the Czech Republic. These primers were tested against 9 species of Xiphinema and 11 species of Longidorus. Amplification was also observed for X. inaequale, X. italiae and X. lambertii. Three additional markers, mitochondrial cytochrome c oxidase subunit 1, ribosomal D2/D3 expansion segment of the 28S gene and 18S gene, were amplified and sequenced for X. brevicollum, X. inaequale and X. lambertii belonging to X. americanum-group. Comparison of cox1 sequences of X. brevicollum from the Czech Republic with X. taylori from the Slovak Republic (accession number AM086702) suggested that these populations represent the same species.  相似文献