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Now showing items 49 - 64 of 1953

  • Resistance to Rhynchosporium secalis in six Nordic barley genotypes

    J. Robinson   M. Jalli   H. Lindqvist  

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  • Diversity among Finnish net blotch isolates and resistance in barley

    J. Robinson   M. Jalli  

    Seedlings of a differential barley (Hordeum vulgare L.) series (21 genotypes) and of six check genotypes were used in the greenhouse to assess variation in virulence among 20 single-spore isolates of the net blotch pathogen, Pyrenophora teres Drechs. f. teres Smedeg., collected from various sites in Finland. The experiment was run twice and symptom expression was recorded on the first three leaves. Analysis of second leaf symptom scores from Run 1 indicated differences in virulence between isolates, all of which were pathogenic, and differential resistance among the barleys. The virulence of P. teres isolates appeared to be conditioned by the host barley from which the isolate derived; the average virulence of isolates collected from a susceptible host was greater than that of isolates collected from a less susceptible host. Results from Run 2 were similar regarding resistance within the barleys, but variation in virulence among the P. teres isolates was not consistent with that from Run 1. CI 9819 carries duplicate genes for resistance to P. teres (Rpt1b and Rpt1c), and CI 7548 possesses Rpt3d. Both genotypes were highly resistant to all isolates. The Rpt1 a gene of Tifang (CI 4407) conferred resistance to all isolates in Run 2, but only to about half of the isolates in Run 1. The checks, including two of the symptomatically most resistant Nordic barley genotypes, were universally susceptible during these stringent tests. No selective pressure has been placed on Finnish isolates of P. teres through previous deployment of major resistance genes, and it is speculated that any variation in virulence among isolates is likely to be due to a combination of evolutionary forces including, natural selection, random genetic drift and gene flow.
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  • Sensitivity of Resistance to Net Blotch in Barley

    J. Robinson   M. Jalli  

    The aim of this study was to demonstrate various methods of analysing terminal net blotch, Pyrenophora teres Drechs. f. teres Smedeg., severity data from 15 spring barleys, Hordeum vulgare L., grown in Finnish official variety trials in five environments. The analyses have been developed and used principally by plant breeders for assessing crop yield, but lend themselves to use by plant pathologists. Pyrenophora teres is the major barley phytopathogen in Finland and improved resistance to it is sought. Joint regression analysis (JRA) and an additive main effects and multiplicative interaction (AMMI) model were used to investigate the data. Statistically significant genotype by environment (GE) interaction for resistance was indicated, and this included qualitative (crossover) interactions among genotypes over environments. A stable, non-sensitive, response to net blotch over environments, combined with a low mean score for terminal severity of the disease characterized the six-row barley ‘Thule’ which showed statistically significant crossover interaction only with ‘Tyra’. ‘Kustaa’ exhibited the lowest mean terminal net blotch severity, but was relatively sensitive to net blotch. ‘Arve’ exhibited severe terminal net blotch in all environments, was relatively sensitive to environment and exhibited no crossover interaction with other genotypes. AMMI analysis appeared to represent a useful method for analysing these disease severity data, facilitating the selection of useful sources of resistance. Plots of AMMI-adjusted mean net blotch severities against first principal component axis (PCA) scores were informative for differentiating genotype response over environments, and are therefore potentially useful to plant pathologists and barley breeders seeking to gauge and subsequently improve the resistance status of barley to net blotch. Zusammenfassung Das Ziel dieser Untersuchung bestand darin, bei fünfzehn Sommergerstensorten (Hordeum vulgare L.), die im Rahmen amtlicher finnischer Sortenversuchen an fünf verschiedenen Standorten geprüft wurden, verschiedene Verfahren zur Analyse des terminalen Befalls durch die Netzfleckenkrankheit (Pyrenophora teres Drechs. f. teres Smedeg.) zu demonstrieren. Die Untersuchungsmethoden wurden von Pflanzenzüchtern entwickelt und dienen ihnen zur Ertragsbestimmung. Sie eignen sich jedoch auch für pflanzenpathologische Studien. Pyrenophora teres ist das bedeutendste Pathogen der Gerste in Finnland, und eine verbesserte Resistenz gegen diesen Erreger ist ein wichtiges Ziel. Die Daten wurden regressionsanalytisch und mit Hilfe eines Modells ausgewertet, das die additiven Haupteffekte und die multiplikativen Interaktionen berücksichtigte (AMMI-Modell). Für die Resistenz egab sich eine statistisch signifikante Interaktion Genotyp/Umwelt (GE), die qualitative Interaktionen (‘Überschneidungen’) zwischen Genotypen über verschiedene Umweltbedingungen einschloi. Eine stabile, nicht anfällige Reaktion auf die Netzfleckenkrankheit auf den verschiedenen Standorten, kombiniert mit einem niedrigen Mittelwert für die terminale Befallsstärke der Krankheit charakterisierte die sechszeilige Gerstensorte ‘Thule’, die nur mit ‘Tyra’ statistisch signifikante Überschneidungen zeigte. ‘Kustaa’ zeigte die niedrigste mittlere terminale Befallsstärke, war jedoch relativ anfällig gegen die Krankheit. ‘Arve’ wies an allen Standorten eine hohe terminale Befallsstärke auf, reagierte relativ empfindlich auf die Umweltverhältnisse und zeigte keine Überschneidungen mit anderen Genotypen. Die AMMI-Analyse erwies sich als nützliches Verfahren zur Analyse dieser Befallsstärke-Daten, sie ermöglichte die Selektion nützlicher Resistenzquellen. Wurden die AMMI-adjustierten mittleren Befallsstärken gegen die ersten PCA-Werte (Achse der Hauptkomponente) aufgetragen, so war es möglich, die Reaktionen der Genotypen über die Umweltverhältnisse zu differenzieren. Damit kann dieses Verfahren Pflanzenpathologen und Gerstenzüchtern Nutzen bringen, die den Resistenzstatus von Gerste gegen die Netzfleckenkrankheit beurteilen und verbessern wollen.
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  • Assessment of disability: Prevalence of fear in subgroups of Fibromyalgia Syndrome (FMS) patients

    J. Robinson   D. Turk   T. Burwinkle   M. Showlund   A. Gest  

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  • Development of the Ocular Lens.Edited by Frank J Lovicu and Michael L Robinson

    Tsonis   Panagiotis A  

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  • Quantitative resistance to Pyrenophora teres in six Nordic spring barley accessions

    J. Robinson   M. Jalli  

    Resistance to Pyrenophora teres Drechs. f. teres Smedeg., the net blotch pathogen, was studied in six 6-row Nordic spring barleys (Hordeum vulgare L.) in the field and in the greenhouse. The barley genotypes were: Arve, Agneta, Artturi, H6221, Pohto and WW7977. Disease progress was monitored in the field (1994 and 1995) in small artificially infected plots, sown at commercial seeding rates, and in infected hill plots (1994). Areas under the disease progress curves (AUDPC) and apparent infection rates (r) we're calculated for the uppermost 3 or 4 leaves. Terminal severities (TS) were also recorded. Infection response of seedlings to a range of P. teres isolates was assessed in the greenhouse using a standard scale. In small plots in the field, Arve and Agneta were very susceptible to P. teres infection, as indicated by large values for AUDPC and TS. H6221 and WW7977 were highly resistant, while Artturi and Pohto were moderately resistant. In hill plots the situation was similar, except that Artturi and Pohto appeared less resistant than in the small plots. The relatively greater resistance of H6221 and WW7977 was reflected in seedling infection responses. According to the results of these experiments, H6221 and WW7977 possess adequate levels of quantitative resistance to P. teres to make them useful parents in future crossing programs aimed at improving net blotch resistance in Finnish spring barleys.
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  • Studies in Spanish American Population History.by David J. Robinson

    Review by: Nicolás Sánchez-Albornoz  

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  • The structure and bonding of carbonate on Ag(1 1 0): a density-functional theory study

    J. Robinson   D.P. Woodruff  

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  • The West Indies, Commerce, and a Play for U.S. Empire: Recovering J. Robinson\"s \"The Yorker\"s Stratagem\" (1792)

    Sean X. Goudie  

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  • Intra-uterine and juxtanatal repair of syndactyly in foetal mice

    J. Robinson   K.C. Oberg   W.M. Kirsch   V.E. Wood  

    39 foetal mice with genetic syndactyly were identified in utero at 17 days of gestation, and the right hindfoot extruded through the uterus. The syndactylous digits were separated by simple incisions. In one group (n = 25) digit separation was maintained during wound healing by the interdigital application of a silver microclip. Digit separation was also assessed in a second group of newborn mice less than 24 hours old (juxtanatal population, n = 24). Two foetuses (5%) and six newborns (25%) developed digital necrosis following microclip application. In the remaining microchlipped animals (23 intrauterine and 10 juxtanatal), microclip application maintained digit separation, allowing wound healing to occur with epithelialization of the separated digits. No inflammation or scar formation occurred. In the third group (n = 22) without microclip application, the digital skin reapproximated and webbing recurred during wound healing. These studies demonstrate the need to maintain digit separation during wound healing following intra-uterine or juxtanatal syndactyly repair.
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  • Genes for resistance in barley to Finnish isolates ofRhynchosporium secalis

    J. Robinson   H. Lindqvist   M. Jalli  

    Twenty Finnish isolates of Rhynchosporium secalis (Oud.) J.J. Davis, the causal agent of scald, were taken from infected barley (Hordeum vulgare L.) plants and inoculated on to seedlings of a differential series of barley containing a range of major genes for resistance to the fungus, as well as on to six Nordic 6-row spring barleys and three winter ryes (Secale cereale L.). These fungal isolates derived from four sites and three host varieties. Disease development was monitored on two leaves of seedlings in the greenhouse employing a standard scale, and on adult plants in the field by assessing the diseased area on the three uppermost leaves. A comparison was also made between the pathogenicity and virulence of ten Finnish and ten Canadian R. secalis isolates. The Finnish isolates varied in virulence, but with the exception of Algerian (CI 1179) seedlings and adult La Mesita (CI 7565) all seedlings and adult plants of the entire differential series were resistant to all isolates. Canadian isolates were, on average, less virulent than Finnish isolates. All the Nordic checks were susceptible to all Finnish and seven Canadian isolates, but differences in the degree of susceptibility were evident. Isolates of R. secalis from barley were non-pathogenic on rye, isolates from Elymus repens L. were non-pathogenic on barley and rye, and isolates from rye were only pathogenic on rye. Finnish R. secalis isolates contain no redundant pathogenic diversity. The differential series represents a useful, but as yet untapped, source of resistance to R. secalis for Finnish barley breeders.
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  • Diallel analysis of net blotch resistance in doubled haploid lines of Nordic spring barleys

    J. Robinson  

    A half-diallel was made between five six-rowed Nordic spring barleys to study the genetics of resistance to net blotch. Twenty-five doubled-haploid (DH) lines from each cross and the parents were sown in hill plots in Finland in 1997 and 1998. The plots were artificially inoculated with Pyrenophora teres Drechs. f. teres Smedeg. and assessed for resistance to net blotch. There were statistically significant differences in resistance of the five parents to net blotch. General combining ability (GCA) of the parents and specific combining ability (SCA) effects in the progeny were statistically significant in both years, but GCA effects predominated. Evidence for additive epistasis was minimal. Progeny of a particular cross were less resistant to net blotch than the better parent. The most resistant progeny were derived from the cross between the two most resistant parents, Pohto and WW7977, and resistance was governed by at least eleven effective factors. Narrow sense heritability esti mates for resistance to net blotch were high during both years (0.84-0.99). It appears that net blotch resistance of progeny from crosses can be largely predicted from reactions of the parents. Quantitative resistance to net blotch can be further advanced by identification and incorporation of superior parents, from a screening such as reported here, into a recurrent selection breeding programme.
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  • Social Fabric and Spatial Structure in Colonial Latin Americaby David J. Robinson

    Review by: Richard M. Morse  

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  • (164) Symptom reporting in people with fibromyalgia

    J. Robinson   H. Wilson   K. Swanson   D. Turk  

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  • Studying Latin America. Essays in Honor of Preston E. Jamesby David J. Robinson

    Review by: J. A. Steers  

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  • Studying Latin America: Essays in Honor of Preston E. James.by David J. Robinson

    Review by: John P. Harrison  

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