bluuebunny/crossref_metadata_2025_split huggingface dataset:
Release and establishment of a biological control agent, Psyllaephagus pilosus for eucalyptus psyllid (Ctenarytaina eucalypti) in Ireland
Authors: CHAUZAT MARIE‐PIERRE , PURVIS GORDON , DUNNE RICHARD 
Published: July 2006

SummaryAn Australian parasitoid wasp, Psyllaephagus pilosus, was collected from a previous release site in France and introduced into a commercial eucalyptus foliage plantation in Co. Kerry in the south west of Ireland to control the eucalyptus (blue gum) psyllid Ctenarytaina eucalypti. The first parasitised psyllid nymphs were observed 26 days after the release was made in late May 1998, and 49 days elapsed before a new generation of adult parasitoids was seen. Visually assessed indices of psyllid parasitism and adult wasp incidence were used to quantify the pattern of adult dispersion and establishment. A second generation of adult wasps emerged in late August, initiating a rapid spread of parasitism throughout the release site during September that culminated in a peak rate of almost 100% parasitism by late October. Subsequently by the end of 1998, an apparently random process of dispersion and successful natural colonisation occurred at eight out of ten monitored plantations at distances up to 70 km from the release point. The first colonisers of the other two sites arrived very late in 1998, and consequently failed to establish viable populations by the following summer. Probably this failure was because the small numbers of colonisers had arrived too late in the growing season to effect population establishment before the onset of winter. Assisted introductions were, therefore, made at these sites in June and August 1999, respectively. Once fully established, the parasitoid had no difficulty in surviving winter conditions at all monitored sites and demonstrated excellent potential as a biological control agent.
Dissection and manipulation of metabolic signalling pathways
Authors: HALFORD N G , HEY SANDRA , JHURREEA D , LAURIE S , MCKIBBIN R S , ZHANG Y , PAUL M J 
Published: July 2006

SummaryThe partitioning of resources between different plant organs and compounds is an important determinant of crop quality. We are attempting to change resource partitioning in crop plants by manipulating the cellular mechanisms involved in metabolite sensing and signalling. One of the proteins involved is SnRK1 (sucrose nonfermenting‐1‐related protein kinase 1), so‐called because of its homology and functional similarity with sucrose non‐fermenting 1 (SNF1) of yeast. SnRK1 is a protein kinase that plays a key role in the global control of plant carbon metabolism. Here we review studies on the characterisation of SnRK1 gene families, SnRK1 regulation and function, and the identification of SnRK1‐interacting proteins. We also describe some potential applications of manipulating SnRK1 activity, including controlling sprouting in stored potato tubers, inducing male sterility in barley and increasing sterol levels in oilseeds.
Economic consequences for UK farmers of growing GM herbicide tolerant sugar beet
Authors: MAY M J 
Published: July 2006

SummaryWeed control is important and one of the more expensive inputs to sugar beet production. The introduction of genetically modified herbicide tolerant (GMHT) sugar beet would result in a major saving in weed control costs in the crop for growers, including control of problem weeds such as perennial weeds and weed beet. However, there would be other economic consequences of growing GMHT beet, some of which would manifest themselves in other parts of the rotation, such as the previous crop, the cereal stubbles that proceed most beet crops, soil tillage and spray application. The average national saving for UK sugar beet growers if they could use the technology would be in excess of £150 ha−1 yr−1 or £23 million yr−1, which includes reductions in agrochemical use of c. £80 ha,−1 yr−1 or £12 million yr−1. However, for some growers, the gains would be much larger and for a few, less than these figures. The possible cost savings are sufficiently large that they could ensure that sugar beet production, with its regionally important environmental benefits as a spring crop, remains economically viable in the UK post reform of the EU sugar regime.
Growth, radiation use efficiency and yield potential of enset (Ensete ventricosum) at different sites in southern Ethiopia
Authors: TSEGAYE ADMASU , STRUIK P C 
Published: July 2006

SummaryKnowledge on the physiological parameters that determine the growth of enset (Ensete ventricosum) and on how these parameters develop over time and affect yield under field conditions is scarce. Field experiments were carried out at three sites in southern Ethiopia using suckers of several clones to generate crop physiological parameters and to describe the time course of leaf number, leaf area and plant height. Yield potentials at different sites were estimated using these parameters and weather data, and compared with the actual yield.Plant height and LAI increased faster at Awassa and Areka than at Hagereselam because of a higher leaf appearance rate associated with temperatures being closer to the optimum. The trend in plant height was best described by a logistic function, whereas the trend in LAI was best described by a logistic function only at Awassa and Areka.A high leaf appearance rate (0.18 leaves day−1) during early growth at Awassa and Areka made it possible that leaves that were senesced during unfavourable climatic conditions could be rapidly replaced without strong fluctuation in leaf area index. At Hagereselam, however, the rate of leaf appearance (0.09 leaves day−1) was too small to compensate for the decline in the number of green leaves per plant during adverse conditions and thus LAI fluctuated over the whole growing period.The trend in fraction of PAR intercepted was best described by a generalised logistic function. At 300 days after transplanting the suckers, LAI reached a value of 4.5 and enset clones intercepted 92–97% of incoming PAR. The mean extinction coefficient was between 0.56–0.91 and radiation use efficiency (RUE) ranged from 1.43–2.67 g MJ−1. Dry matter kocho yield potentials of 17.1 to 33.9 t ha‐1 yr‐1 were estimated for enset clones. Important yield potential differences existed between clones mainly because of differences in radiation use efficiency that was probably partly associated with viral infection. The average ratio of actual yield:yield potential (0.24) was low mainly because of large losses associated with traditional fermentation techniques, yield reducing cultivation methods such as repetitive transplanting and leaf pruning, presence of diseases, lack of adequate fertilisation and shortage and uneven distribution of rainfall.
Resistance to crown rot (Phytophthora cactorum) in strawberry cultivars and in offspring from crosses between cultivars differing in susceptibility to the disease
Authors: EIKEMO H , STENSVAND A , DAVIK J , TRONSMO A M 
Published: July 2006

SummaryDuring a period of five years (1998‐2002), 26 strawberry cultivars and five selections were tested for resistance to crown rot. Cold stored plants inoculated with zoospores of Phytophthora cactorum were used in all experiments. The results showed that resistance to P. cactorum varies greatly between cultivars, and the most resistant ones were Senga Sengana, Induka, Melody, Glima and Bogota, while the most susceptible were Tamella, Inga, Evita and Jonsok. The results were compared to those obtained by other authors, and there were clear indications that the genetic background affects the degree of susceptibility to P. cactorum. Many of the most resistant cultivars descend from Senga Sengana (e.g. Bounty, Glima, Induka and Melody), and several of the most susceptible cultivars have common parentage (e.g. Inga, Tamella, Elsanta and Evita). In a resistance test of the progeny from two separate crosses between a resistant and a susceptible cultivar 61% and 65% of the offspring were intermediately to very susceptible, and 17% and 13% were resistant at the level of Senga Sengana. Hence, there is a high risk of losing offspring with high levels of resistance if selection for resistance to crown rot is not performed at an early stage in a breeding programme.
Genetic basis of yield as viewed from a crop physiologist's perspective
Authors: SLAFER G A 
Published: July 2006

SummaryThe final yield of a crop is the product of growth during the growing season and a number of developmental processes occurring throughout the life cycle of a crop, with most genes influencing the final outcome to a degree. However, recent advances in molecular biology have developed the potential to identify and map many genes or QTLs related to various important traits, including yield, plant adaptation and tolerance to stresses. Significant G×E interactions for yield have been identified, as have interactions associated with QTLs for yield. However, there is little evidence available to confirm that a QTL for yield from a parental line in one mapping population may improve yield when transferred into an adapted, high‐yielding line of another population. In order to narrow the apparent gap between the genotype and the phenotype with regard to yield, it is important to identify key traits related to yield and then attempt to identify and locate the genes controlling them. The partitioning of the developmental time to anthesis into different phases: from sowing to the onset of stem elongation and from then to anthesis, as a relatively simple physiological attribute putatively related to yield, is discussed. If the relationship holds in a wider range of conditions and the genetic factors responsible are located then the genetic basis of yield should be identified. There has also been significant progress in crop simulation modelling. Using knowledge of crop physiology and empirical relationships these models can simulate the performance of crops, including the G×E interactions. Such models require information regarding the genetic basis of yield, which are included in the form of genetic coefficients. Essentially models are constructed as decision‐making tools for management but may be of use in detecting prospective traits for selection within a breeding programme. Problems associated with this approach are discussed. This review discusses the need to use crop physiology approaches to analyse components of yield in order to reliably identify the genetic basis of yield.
Geminivirus classification and nomenclature: progress and problems
Authors: FAUQUET CLAUDE M , STANLEY JOHN 
Published: July 2006

SummaryDuring the last few years there has been some confusion among geminivirologists about how to determine the taxonomic status of a geminivirus and provide appropriate names for newly discovered viruses. The Seventh Report of the International Committee on Taxonomy of Viruses (ICTV) published in 2000, that provides guidelines for classification within the family Geminiviridae, is rapidly becoming obsolete, due mainly to the large number of complete genomic sequences that have become available. These sequences have provided a wealth of information with which to establish a coherent and durable taxonomic system, although the realisation that frequent inter‐species recombination events occur has introduced an additional level of complexity. This has resulted in a number of individual initiatives that were not fully compatible with current classification. The Geminiviridae Study Group of the ICTV exploited the last two International Geminivirus Workshops, held in Puerto Rico (1998) and Norwich, UK (2001), to debate some of the issues arising, allowing taxonomic proposals to be formulated that are in the process of being accepted by the ICTV for publication in the Eighth Report due in 2004. The present paper reviews these established principles and provides a reference with which to name and classify geminiviruses appropriately.
The theoretical basis and practical application of relationships between different disease intensity measurements in plants
Authors: MCROBERTS N , HUGHES G , MADDEN L V 
Published: July 2006

SummaryThe literature concerning relationships among different measures of plant disease intensity is reviewed. Some previous confusion over the definition of the terms “incidence” and “severity” is noted and clarified. The review highlights the common features of relationships between incidence and severity, incidence and disease density, and incidence at pairs of scales in a spatial hierarchy. These relationships often show a similar saturation curve form that can frequently be described empirically using the complementary log‐log transformation. A catalogue of alternative functional forms is provided. Practical applications in varietal evaluation are discussed.
Agrobacterium tumefaciens‐mediated transformation and regeneration of herbicide resistant onion (Allium cepa) plants
Authors: EADY COLIN , DAVIS SHEREE , FARRANT JULIE , READER JILL , KENEL FERNAND 
Published: July 2006

SummaryTransgenic onion plants (Allium cepa) tolerant to herbicides containing active ingredients glyphosate and phosphinothricin were recovered from immature embryos of open pollinated and hybrid parent onion lines at a maximum transformation frequency of 0.9%. Transformants of different onion cultivars, grown on different selective agents and confirmed by Southern analysis, thrived with no apparent ill effects when sprayed with the respective herbicides at double the recommended field dosage for weed eradication. This study demonstrates that the transformation process described previously can be used with different selective agents and is cultivar independent.
Efficacy and phytotoxicity of lime sulphur in organic apple production
Authors: HOLB I J , DE JONG P F , HEIJNE B 
Published: July 2006

SummaryCurative and preventive efficacy and phytotoxicity of lime sulphur spray schedules, based on a warning system, were evaluated in the Netherlands during two growing seasons under field conditions. In most cases, lime sulphur treatments applied either curatively or preventively resulted in significantly lower scab damage on both the leaves and fruits compared to wettable sulphur treatments. However, all lime sulphur treatments showed high phytotoxicity values, reduced leaf size and had a tendency to a reduced yield quality compared to all other treatments. For curative schedules of lime sulphur on scab control, phytotoxicity and yield did not differ significantly from preventive schedules of lime sulphur. However, the use of a warning system combined with curative schedules of lime sulphur saved one and two lime sulphur sprays in 2000 and 2001, respectively, compared to the preventive treatments of lime sulphur. Our results demonstrated that a curative spray programme with lime sulphur at 0.75–2%, applied 35–45 h after predicted infection periods, can provide effective primary apple scab control, but no benefit in either yield or fruit quality was reached under organic growing conditions. Moreover, research herein clearly showed that organic growers are forced to find a balance between good efficacy and phytotoxic effects of lime sulphur.
Selection, biological properties and fitness of resistance‐breaking strains of Tomato spotted wilt virus in pepper
Authors: THOMAS‐CARROLL M L , JONES R A C 
Published: July 2006

SummaryIn glasshouse tests, infective sap from plants infected with 17 different isolates of Tomato spotted wilt virus (TSWV) from four Australian states was inoculated to three Capsicum chinense accessions (PI 152225, PI 159236 and C00943) carrying single genes that confer hypersensitive resistance to TSWV. The normal response to inoculation was development of necrotic (hypersensitive) local lesions in inoculated leaves without systemic invasion, but 3/1386 infected plants also developed systemic susceptible reactions in addition to hypersensitive ones. Similarly when two isolates were inoculated to C. chinense backcross progeny plants, 1/72 developed systemic susceptible reactions in addition to localised hypersensitive ones. Using cultures from the four plants with susceptible reactions and following three to five further cycles of serial subculture in TSWV‐resistant C. chinense plants, four isolates were obtained that gave systemic susceptible type reactions in the three TSWV‐resistant accessions, and in TSWV‐resistant cultivated pepper (C. annuum). When three of these isolates were inoculated to tomato (Lycopersicon esculentum) breeding lines with single gene resistance to TSWV, resistance was not overcome. Similarly, none of the four isolates overcame partial resistance to TSWV in Lactuca virosa. When TSWV isolates were inoculated to tomato breeding lines carrying partial resistance from L. chilense, systemic infection developed which was sometimes followed by ‘recovery’. After four successive cycles of serial passage in susceptible cultivated pepper of a mixed culture of a resistance‐breaking isolate with the non resistance‐breaking isolate from which it came, the resistance‐breaking isolate remained competitive as both were still found. However, when the same resistance‐ breaking isolate was cultured alone, evidence of partial reversion to wild‐type behaviour was eventually obtained after five but not four cycles of long term serial subculture in susceptible pepper, as by then the culture had become a mixture of both types of strain. This work suggests that resistance‐breaking strains of TSWV that overcome single gene hypersensitive resistance in pepper are relatively stable. The findings have important implications for situations where resistant pepper cultivars are deployed widely in the field without taking other control measures as part of an integrated TSWV management strategy.
Blockage of stylet tips as the mechanism of resistance to virus transmission by Aphis gossypii in melon lines bearing the Vat gene
Authors: MARTIN B , RAHBÉ Y , FERERES A 
Published: July 2006

Summary Aphis gossypii is the main virus vector in muskmelon crops. The melon gene Vat confers resistance to non‐persistent virus transmission by this aphid. The mechanism of this resistance is not well understood, but no relationship has been detected between resistance and the probing behaviour of aphids on resistant plants. Results presented here suggest that temporary blockage of aphid stylet tips preventing virus particle release may explain the resistance conferred by Vat gene. We performed experiments in which viruliferous aphids were allowed to probe different sequences of resistant (Vat‐bearing) and/or susceptible melon plants. The results demonstrated that A. gossypii inoculates Cucumber mosaic virus (CMV) efficiently in susceptible plants having previously probed resistant plants, showing that the resistance mechanism is reversible. Furthermore, the infection rate obtained for susceptible plants was the same (25%) regardless of whether the transmitting aphid had come directly from the CMV source or had subsequently probed on resistant plants. This result suggests that virus is not lost from stylet to plant during probing of resistant plants, supporting the temporary blockage hypothesis. We also found that the ability of Myzus persicae to transmit CMV is noticeably reduced after probing on resistant plants, providing evidence that this aphid species also responds to the presence of the Vat gene. Finally, we also found that in probes immediately after virus acquisition M. persicae inoculates resistant plants with CMV more efficiently than susceptible plants, perhaps because the Vat gene product induces increased salivation by this aphid.
Wild flower seed predation byPterostichus madidus(Carabidae: Coleoptera)
Authors: HURST C , DOBERSKI J 
Published: July 2006

SummaryThe objective of the study was to investigate the ability ofPterostichus madidus, one of the most abundant carabid beetles in the United Kingdom, to consume wildflower seeds. The plant species chosen are commonly included in wildflower seed mixes sown to enhance the biodiversity of arable field margins, and hence any seed predation could potentially reduce successful seedling establishment. The study combined cafeteria style laboratory feeding experiments with predation studies in an established field margin.In laboratory studies thePterostichus madidusconsumed both unimbibed and imbibed seeds ofCentaurea scabiosa, Galium verum, Leucanthemum vulgareandPrimula veris. Seed consumption was still evident whenDrosophilapupae were also supplied, although there was significant preference for the pupae. Placement of seeds in the field showed high levels of seed consumption, although part of this was attributed to slugs. Carabid beetles may have a significant role as wild flower seed predators and thus may affect establishment of re‐seeded flower‐rich meadows.
The coincidence of thrips and dispersed pollen in PNRSV‐infected stonefruit orchards – a precondition for thrips‐mediated transmission via infected pollen
Authors: MILNE J R , WALTER G H 
Published: July 2006

SummaryRecent laboratory studies have demonstrated that Prunus necrotic ringspot virus (PNRSV) (family Bromoviridae) can be readily transmitted when thrips and virus‐bearing pollen are placed together on to test plants. For this transmission mechanism to result in stonefruit tree infection in the field, PNRSVbearing pollen must be deposited onto surfaces of stonefruit trees on which thrips also occur. In a previous paper, we demonstrated that almost all pollen in a PNRSV‐infected Japanese plum orchard in southeastern Queensland was deposited onto flowers, whereas few grains occurred on leaves and none on stems. Here, we present results of our investigation of thrips species composition, distribution and abundance on stonefruit trees in the same study area as our previous pollen deposition study. We collected a total of 2010 adult thrips from 13 orchards during the 1989, 1991 and 1992 flowering seasons of which all but 14 were in the suborder Terebrantia. Most (97.4%) terebrantian thrips were of three species, Thrips imaginis, Thrips australis and Thrips tabaci. Thrips tabaci as well as species mixtures that included T. imaginis, T. australis and T. tabaci have been shown to transmit PNRSV via infected pollen in laboratory tests. Adult thrips were frequently collected from flowers but rarely from leaves and never from stems. Large and significant differences in numbers of T. imaginis, T. australis and T. tabaci adults in flowers occurred among orchards and between seasons. No factor was conclusively related to thrips numbers but flowers of late‐flowering stonefruit varieties tended to hold more thrips than those of early‐flowering varieties. Our results indicate that the common thrips species present on stonefruit trees in the Granite Belt are also ones previously shown to transmit PNRSV via infected pollen in the laboratory and that these thrips are concentrated in tonefruit flowers where most stonefruit pollen is deposited. These results contribute to mounting circumstantial evidence that stonefruit flowers may be inoculated with PNRSV via an interaction of thrips with virus‐bearing pollen and that this transmission mechanism may be an important cause of new tree infections in the field
The development of a model to assess the effects of rabbit grazing on grass
Authors: DENDY JULIE , MCKILLOP GORDON , FOX SUE , WESTERN GAVIN , LANGTON STEVE 
Published: July 2006

SummaryGrass for use as silage is widely grown in the UK. However there is little information on the effects of rabbit grazing on crop yield. In a three‐year trial, grass was grown in six enclosures following current agronomic procedures and was subjected to grazing by two population densities of rabbits. The annual yield loss at the end of the trial was found to be 1% per rabbit ha−1. The yield loss per rabbit was calculated to be around 200 kg and the financial loss was calculated as £3.40 per rabbit at 1998 prices (approx. £17 t−1).This new information provides farmers with a better understanding of the economics of damage caused by rabbits enabling them to make more informed decisions as to whether their rabbit population needs to be managed, or whether their crop needs to be protected by some other means.