bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Heterodera avenae on winter wheat in France: experiments with resistant and susceptible varieties
Authors: RIVOAL R. , DOUSSINAULT G. , HULLE M. 
Published: February 2008

SummaryA succession of oat crops resistant or susceptible to Heterodera avenue produced plots lightly or moderately infested with the pest with little risk of interaction with other soil pathogens in succeeding cereal crops. Using these plots, the effects of the nematode on growth and yield of winter wheat were studied. The nematode affected the crop throughout its development, with a marked effect on yield. The effects of H. avenue are similar to those of water stress and are accentuated to a greater or lesser extent by climatic conditions. In the field the efficacy and durability of resistant genes incorporated in wheat and oats were checked. After four‐years' cultivation of oats (cv. Panema), no resistance‐breaking pathotypes were detected. Some advanced wheat lines with nematode resistance were also tolerant of nematode attack.
The response of spring barley and winter wheat to Avena fatua population density
Authors: WILSON B. J. , COUSENS R. , WRIGHT KATHRYN J. 
Published: February 2008

SummaryPopulations of Avena fatua were established in crops of spring barley and winter wheat, and relationships derived between yield and other crop parameters, and weed density. Competitive effects of A. fatua, which were similar to those found in other countries, were greatest at low crop densities. Crop head numbers were reduced proportionately less than crop yield, indicating that competition was affecting other yield components. Competition increased the proportion of thin grain of barley but not of wheat. Competition had little effect on the moisture content and the contamination of the harvested grain by A. fatua, suggesting that at threshold populations these factors are unlikely to be of economic significance. It was concluded that at average crop densities, low infestations of A. fatua are likely to result in cereal yield losses in the region of 1 % for each A. fatua plant m‐2.
Surveys of diseases of winter wheat in England and Wales, 1976–1988
Authors: POLLEY R. W. , THOMAS M. R. 
Published: February 2008

SummarySamples from 300 – 400 randomly selected winter wheat crops were taken annually at growth stage 73 – 75 from 1976 to 1988 with the exception of 1983 and 1984. The number of samples from each region was proportional to the area of wheat grown in each region. The percentage of the area of the top two leaves affected by diseases, the severity of ear and stem base diseases and, in 6 years, the severity of take‐all were recorded. Septoria tritici and Septoria nodorum were, on average, the most severe of the foliar diseases and eyespot (Pseudocercosporella herpotrichoides) was the most severe of the stem base diseases. Regional differences in levels of S. tritici, brown rust, sharp eyespot and nodal fusarium were significant. Cultivar resistance affected disease severity, and previous cropping patterns particularly affected take‐all and eyespot. Eyespot and sharp eyespot were less severe in late‐ than in early‐sown crops. The percentage of crops treated with a fungicidal spray increased from 14% in 1976 to over 90% between 1983 and 1985. Use of benzimidazole fungicides applied at growth stage 31 declined, while use of morpholines from flag leaf emergence onwards increased between 1985 and 1988.
Genotype by environment interaction in the assessment of tolerance of partially resistant potato clones to potato cyst nematodes
Authors: DALE M. F. B. , PHILLIPS M. S. 
Published: February 2008

SummaryGenotype by environment interactions in a number of field trials in different years are examined in relation to tolerance of potato cyst nematodes and the subsequent yield losses. A biplot technique is used to display the interaction effects graphically and facilitate identification of any patterns in the data. The results are assessed and discussed in relation to breeding strategies and the variation found between different nematode populations.
The use of non‐destructive measurement and physiological models of yield determination to investigate factors determining differences in seed yield between genotypes of “desi” chickpeas (Cicer arietum)†
Authors: WILLIAMS J. H. , SAXENA N. P. 
Published: February 2008

SummaryMathematical models for yield determination are most commonly used to estimate the probable final crop yield in a given circumstance based on measured physiological parameters but the reverse may be done. Simple models of yield determination may be used to estimate the model parameters associated with a measured final product. One can then obtain a better understanding of the physiological attributes of large numbers of genotypes without the labour intensive destructive measurements usual to interpretive physiology. This approach has been demonstrated using 120 chickpea genotypes.The total mass, seed yield, vegetative (Dv) and reproductive (Dr) durations were observed and the crop growth rates (C) and partitioning to seed (p) estimated. The contribution of variations in C., Dr, and p to the variations in seed yield were analysed by regression techniques. Contrary to expectations based on other crops, the variations in C were an important source of yield variation, rather than variations in p and Dr. Counteracting relationships existed between the parameters of the yield model; C was inversely related to Dr and p. The influence of these features of chickpea yield determination on genotype by environment interactions and maximising yield are discussed.
Some statistical considerations in the determination of thresholds in ELISA
Authors: FENLON J. S. , SOPP P. I. 
Published: February 2008

SummaryThe presentation of quantitative results from ELISAs is very variable, and, in particular, the positive‐negative threshold or critical value is poorly defined. A simple statistical model is presented which demonstrates how this value may be determined. Depending on what assumptions are made it is possible to estimate the necessary parameters in several different ways. These methods generally form a hierarchy, and greater precision can be achieved by combining variances from several plates. More problematical is the determination of the negative control, and indeed its definition. The results of a series of ELISAs taken from a study of polyphagous predators of the cereal aphid S. avenae are used to illustrate the methods. The ELISAs were done over a period of three months using 86 plates. Recommendations are made for the numbers and levels of controls to be used in future studies.
Analysing dose‐mortality data when doses are subject to error
Authors: RIDOUT M. S. , FENLON J. S. 
Published: February 2008

SummaryIn microbial control of insect pests, the dose of pathogen that a subject actually receives varies because of variation in individual intakes. Variation in intake of a given concentration is equivalent to varying the concentration for a given intake. The main effect of such variation is to flatten the dose‐response curve. If the dose‐variation is known, a correction for this effect can be made; new estimates for the slope and intercept of the probit line are given. However, the correction increases the variance of the estimates. The theory is illustrated with an example in which the diamond‐backed month, Plutella xylostella, was fed varying doses of the specific granulosis virus PxGV; intake assays using similar larvae showed the coefficient of variation of intake volume to be about 40%. Simulation studies showed that correction may be practically important only for the estimation of extreme percentiles, e.g. LD95s.
Effect of anaesthesia with carbon dioxide on vectoring ability and survival of the planthopper Laodelphax striatellus
Authors: CACIAGLI P. 
Published: February 2008

SummaryThis paper describes the effects of carbon dioxide anaesthesia on the ability of the planthopper Laodelphax striatellus to subsequently acquire and transmit maize rough dwarf reovirus (MRDV) and barley yellow striate mosaic rhabdovirus (BYSMV), both propagative in the vector.Anaesthesia reduced the acquisition of MRDV by about 45%, but did not affect acquisition of BYSMV. In serial transfer transmission tests, anaesthesia caused interruption of transmission of both MRDV and BYSMV in about 11% of infectious insects; the effect may be due to impaired ability to find the phloem. The effect was stronger on third instar nymphs than on adults.Transmission of MRDV was resumed 3 days after anaesthesia, but none of the insects that stopped transmitting BYSMV resumed it. The survival of insects which ceased to transmit BYSMV was significantly lower than that of hoppers that continued to transmit. No other effects on survival were detected. A possible interaction of carbon dioxide with BYSMV in L. striatellus is discussed, in the light of effects of carbon dioxide on Drosophila melanogaster infected by some rhabdoviruses.
Detection of bean yellow mosaic virus in gladioli corms by the polymerase chain reaction
Authors: VUNSH RON , ROSNER ARIE , STEIN ADINA 
Published: February 2008

SummaryThe polymerase chain reaction (PCR) method readily detected bean yellow mosaic virus (BYMV) in gladioli leaves, but in initial tests PCR did not detect virus in corm tissue. Extracts of RN A from corm tissue were shown to inhibit the amplification of viral sequences when added to a PCR reaction. An additional purification step for the RNA extracts using a Sephadex G‐50 column eliminated the inhibitory effect and enabled PCR to amplify and detect viral RNA in corm tissue preparations.
Cell membrane punctures during epidermal penetrations by aphids: consequences for the transmission of two potyviruses
Authors: POWELL GLEN 
Published: February 2008

SummaryElectrical penetration graphs (EPGs) were used to investigate aphid stylet activities during brief penetrations and the importance of these events for the nonpersistent transmission of two potyviruses, beet mosaic virus (BMV) and potato virus Y (PVY). Stylet puncture of a cell membrane, recorded as a potential drop, was correlated with the acquisition and inoculation of PVY and acquisition of BMV by Myzus persicae.
The feasibility of producing inbred rather than F1 hybrid cultivars in Brussels sprouts (Brassica oleracea var. gemmifera): an assessment of recombinant inbred lines
Authors: WERNER C. P. , SMITH B. M. , GODWIN R. M. , KEARSEY M. J. 
Published: February 2008

SummaryResults are presented for the performance of improved inbred lines of Brussels sprouts grown in replicated and fully guarded plots. Some lines were identified which out‐performed the reference F1 hybrid, Gower, for the yield of marketable sprouts and for sprout quality. No lines were found which were superior for both of these traits. These results support earlier contentions that inbred line performance in Brussels sprouts could be improved to levels comparable with those of commercial F1 hybrids. The genetic gains required to achieve commercial parity with hybrids for all agronomically important traits continue to be large. Therefore, the use of inbred lines as commercial cultivars can only be viewed as a long term objective. Previous studies have identified additive x additive epistasis and the segregation of many loci as important factors limiting the genetic gains to be expected from a single cycle of crossing and inbreeding. In addition to these factors the current study identifies areas of difficulty encountered when attempting to screen and select large numbers of inbred lines, produced either by single seed descent or by anther culture, in a single season. Evidence is presented which suggests that imperfect visual selection and/or genotype × seasonal interactions may substantially reduce the efficiency of selections based upon a single trial of very many unreplicated lines.
Indices of water deficit in susceptible and resistant cucumbers in response to infection by cucumber mosaic virus
Authors: LEVY D. , MARCO S. 
Published: February 2008

SummaryIndices of water deficit were determined under conditions of non‐limited water supply in cucumber mosaic virus (CMV)‐infected seedlings of the susceptible cv. Bet Alpha. An increase in the concentration of soluble solids, decrease of water and osmotic potentials, and increase of proline concentration were found in the CMV‐infected cotyledons. In the cv. Shimshon, which is resistant to CMV, virus infection caused only a slight change in the concentration of the soluble solids and in the osmotic potential; water potential and proline content were not affected. Concomitantly, infectivity of cotyledons by CMV was much lower in the tolerant cv. Shimshon than in the susceptible cv. Bet Alpha. The possible association of water deficit with virus‐induced growth retardation is discussed.
Relative contribution of nematodes (Caenorhabditis elegans) and bacteria towards the disruption of flushing patterns and losses in yield and quality of mushrooms (Agaricus bisporus)
Authors: GREWAL P. S. 
Published: February 2008

SummaryLaboratory tests of bacteria isolated from the body surface, or from the gut, of a saprophagous rhabditid nematode Caenorhabditis elegans infesting mushrooms (Agaricus bisporus) showed that some bacteria enhanced nematode reproduction and that others inhibited it. As some bacteria were shown to inhibit mycelial growth of the mushroom, the effects of Acinetobacter calcoaceticus var. anitratus, Enterobacter cloacae and Serratia liquefaciens, either alone or in combination with C. elegans, on the flushing patterns, quality and yield of A. bisporus (strain Horst U3) were studied.Bacteria alone had little effect on flushing patterns whereas C. elegans delayed the onset of mushroom production and significantly disrupted the growth pattern of crops, with mushrooms appearing more regularly and not within obvious flushes. Inoculation with bacteria resulted in ‘browning’ of mushrooms that was even more pronounced in C. elegans treatments. Characteristic distortion of sporophores was observed only in the presence of C. elegans. Nematodes commonly colonised sporophores. Bacteria affected the size of nematode populations both on the sporophores and in the casing.Significant yield loss occurred; up to 10% when bacteria were inoculated, up to 27.8% when C. elegans was inoculated, and up to 35% with both bacteria and nematodes. Synergism between C. elegans and A. calcoaceticus var. anitratus was observed; the combination resulted in significantly greater reduction in mushroom yield than any other treatment. It is concluded that bacteria contribute to yield loss and quality deterioration in A. bisporus but that the effects are far greater in the presence of C. elegans.
Effective pollination period in apricot (Prunus armeniaca L.) varieties
Authors: BURGOS L. , EGEA J. , DICENTA F. 
Published: February 2008

SummaryA study of the effective pollination period (E.P.P.) of six varieties of apricot has shown that in the warm climate of the South Mediterranean this parameter is extremely short. The percentage of fruit set of emasculated flowers diminishes rapidly with time. Temperature plays an important role in this process and is responsible for the rapid degradation of the stigma, which hinders pollen germination.
Influence of boron on the reproductive growth of white clover (Trifolium repens L.) cultivars
Authors: MARSHALL A. H. , KHRBEET H. K. , HIDES D. H. 
Published: February 2008

SummaryThe effect of boron on the reproductive growth of four contrasting white clover cultivars was examined in a controlled environment and glasshouse experiment. Plants grown under a nutrient regime excluding boron and those receiving 0.5 mg/litre boron had fewer stolons, reproductive stolons and inflorescences than those receiving 1, 2 or 3 mg/litre. Inflorescences were also smaller and had fewer seeds per floret. A boron concentration of 1 mg/litre gave optimum reproductive growth, higher levels of boron giving no further increase. Peduncle length and nectar quantity, but not nectar quality, were also influenced by boron indicating a possible beneficial effect of this element on pollinator activity.Cultivars differed in both vegetative and reproductive growth. Cv. Gwenda, a small leaved cultivar, had more stolons but fewer inflorescences than cv. Menna and smaller inflorescences than cv. Olwen, a large leaved cultivar. Generally, these cultivars responded similarly to boron.The implications of these results for the reproductive growth of white clover are discussed.
The toxicity of aphicide residues to beneficial invertebrates in cereal crops
Authors: UNAL GULTEKIN , JEPSON PAUL C. 
Published: February 2008

SUMMARYThe toxicity of dimethoate, deltamethrin and pirimicarb residues to Bembidion lampros and Coccinella septempunctata was evaluated by confining groups of insects to winter wheat foliage and soil for 24 h at different times after treatment in the field. Flag leaf residues were found to be more toxic than first leaf residues: soil residues were the least toxic with pirimicarb showing virtually no soil toxicity. In general, dimethoate and deltamethrin showed similar levels of foliar toxicity with flag leaf toxicity on the first day after treatment being in the range 60–80% for B. lampros; deltamethrin was however, less toxic than dimethoate at ground level. Both of these products were more toxic than pirimicarb. The long‐term exposure of insects, surviving the 24 h bioassays, to treated soil at different times following application resulted in further mortality and provided estimates of the maximum levels of mortality that populations of predators might suffer migrating into the crop at different times following application. Dimethoate was shown to be particularly harmful at the current recommended field application rate and reduced doses were proposed to limit the severity of the initial effects.
Composition analysis of tropical white oyster mushroom (Pleurotus citrinopileatus)
Authors: GHOSH N. , MITRA D. K. , CHAKRAVARTY D. K. 
Published: February 2008

SUMMARYThe protein content of the mushroom (Pleurotus citrinopileatus) was determined at different stages of its growth cycle and compared with that of the tropical oyster mushroom Pleurotus sajor‐caju. In both species, maximum protein content was obtained at the bud stage but fell thereafter. All essential amino acids were present in adequate amounts, as were K, P, Fe, Ca, Na, Mg and Mn. The heavy metals, Cu and Zn, were present but in very low concentrations, much below the tolerance limit of human beings.
Biodegradation process and the nature of metabolism of metalaxyl in soil
Authors: DROBY S. , COFFEY M. D. 
Published: February 2008

SUMMARYThe enhanced biodegradation of metalaxyl was studied in tobacco, citrus, avocado and corn soils. The most rapid degradation of metalaxyl occurred in a tobacco soil in which the half‐life (50% degradation) of metalaxyl was 6 days. The main breakdown product of metalaxyl in all soils was the acid metabolite. Ring labelled [14C]metalaxyl incubated for 4 wk in 6 soils demonstrated a low rate of 14CO2 evolution ranging from 2.1% to 11.3% which was unrelated to the biodegradation properties of the soil. A relationship between the concentration of metalaxyl and the subsequent rate of biodegradation was found in the tobacco soils. Higher concentrations of metalaxyl resulted in faster biodegradation rates. A single exposure of tobacco and corn soils to metalaxyl (100 μg/ml or 200 μg/g dry weight of soil) significantly increased their subsequent capacity to degrade the fungicide. Addition of the fungicide thiram or the antibiotics streptomycin and chloramphenicol to an avocado soil resulted in 75% and 51% inhibition of metalaxyl degradation, respectively. A combination of the fungicide and antibiotics resulted in 89% inhibition. The results indicate that enhanced microbial degradation of metalaxyl can occur in a wide range of soils. Under experimental conditions using soil solutions or soil systems, a single application of the fungicide may trigger this event. A wide range of fungi and bacteria appear to take part in degrading metalaxyl.
A satellite RNA of arabis mosaic nepovirus and its pathological impact
Authors: LIU YUAN YI , COOPER J. IAN , EDWARDS MARY LOU , HELLEN CHRISTOPHER U. T. 
Published: February 2008

SUMMARYThree RNA species were encapsidated in arabis mosaic nepovirus from lilac (ArMV‐L): the two genomic RNAs, RNA‐1 and ‐2, and an RNA‐3, Mr. 0.4 × 106. The genomic RNAs from ArMV‐L separated by gel electrophoresis from RNA‐3 were infectious and, during ten passages of this isolate (ArMV‐SF) RNA‐3 was not produced; only RNA‐1 and RNA‐2. When inoculated with the genomic species of ArMV‐L, or with those of other ArMV isolates, RNA‐3 replicated but did not do so in the absence of RNA‐1 and RNA‐2. The RNA‐3 did not share extensive regions of nucleotide sequences with the genomic RNAs but, like them, was polyadenylated and was linked to a protein (VPg) which did not seem essential for replication.When the pathogenicity of ArMV‐L and ArMV‐SF was compared in 42 plant species/cultivars representing 36 genera and 14 families, the following differences were observed: in three species of legume, disease progressed more rapidly when RNA‐3 was present but in species from five families, the presence of RNA‐3 was correlated with symptom amelioration. When RNA‐3 was present, the amounts of ELISA detected antigen were not consistently different in tip leaves of Nicotiana megalosiphon, Chenopodium amaranticolor, C. quinoa or Pisum sativum from those in leaves where RNA‐3 was absent.
Particle purification, properties and epitope variability of Indian tomato leaf curl geminivirus
Authors: MUNIYAPPA V. , SWANSON M. M. , DUNCAN G. H. , HARRISON B. D. 
Published: February 2008

SUMMARYA whitefly‐transmissible stock isolate of Indian tomato leaf curl geminivirus (ITmLCV) was cultured in graft‐inoculated tomato plants and its particles purified from chloroform‐clarified extracts in citrate buffer by precipitation with 70 g/litre polyethylene glycol, ultracentrifugation and sucrose density gradient centrifugation. Contaminating helical filaments were eliminated by banding in caesium sulphate gradients. ITmLCV particles had the shape typical for geminiviruses, measured c. 30 × 20 nm and contained a single major protein of estimated mol. wt c. 32 000. They reacted in immunosorbent electron microscopy with antisera to four other whitefly‐transmitted geminiviruses. ITmLCV reacted with one out of 17 monoclonal antibodies specific for different epitopes in the particle protein of African cassava mosaic geminivirus and five or six out of 10 monoclonal antibodies to the particle protein of Indian cassava mosaic geminivirus. Virus isolates from tomato at nine locations in Karnataka State showed only slight differences in epitope profile, and isolates from four weed species in tomato fields were similar or identical to those from tomato.
Barley mild mosaic virus inside its fungal vector, Polymyxa graminis
Authors: JIANPING CHEN , SWABY A. G. , ADAMS M. J. , YILI RUAN 
Published: February 2008

SUMMARYIn an electron microscope study to investigate the association of barley mild mosaic virus (BaMMV) with its fungal vector, Polymyxa graminis, thin sections were made of zoospores of the vector and of barley roots containing different stages in the life cycle of the fungus. Immunogold labelling was used to identify the virus in sections. Labelled bundles of presumed virus particles were seen in c. 1% of zoospores liberated from plant roots and in zoospores inside zoosporangia. A few zoosporangial plasmodia had localised labelling but no bundles were seen. No virus particles were seen in sections of resting spores.