bluuebunny/crossref_metadata_2025_split huggingface dataset:
Particle purification and properties of cassava Ivorian bacilliform virus
Authors: FARGETTE D. , ROBERTS I. M. , HARRISON B. D. 
Published: February 2008

SummaryA virus found in cassava from the north‐west of the Ivory Coast was transmitted by inoculation with sap extracts to herbaceous species in six plant families. Chenopodium quinoa was used as a propagation host and C. murale was used for local lesion assays. The virus particles are bacilliform, c. 18 nm in diameter, with predominant lengths of 42,49 and 76 nm and a structure apparently similar to that found in alfalfa mosaic virus. Purified preparations of virus particles had A260/A280 of 1.7 ±0.05, contained one protein of Mrc. 22 000, and yielded three species of RNA with Mr (× 10‐6) of c. 0.7, 0.8 and 1.2. Although the virus particles were poorly immunogenic, an antiserum was produced and the virus was detected by enzyme‐linked immunosorbent assay (DAS‐ELISA) in leaf extracts at concentrations down to c. 6 ng/ml. Four other field isolates were also detected, including a strain which caused only mild systemic symptoms in C. quinoa instead of necrosis. The naturally infected cassava source plants were also infected with African cassava mosaic virus (ACMV) but when the new virus was cultured in Nicotiana benthamiana, either separately or together with ACMV, its concentration was the same. The new virus did not react with antisera to several plant viruses with small bacilliform or quasi‐bacilliform particles, and alfalfa mosaic virus reacted only weakly and inconsistently with antiserum to the cassava virus. The new virus, for which the name cassava Ivorian bacilliform virus is proposed, is tentatively classified as the second member of the alfalfa mosaic virus group.
The effects of re‐use of polyethylene glycol priming osmotica upon the development of microbial populations and germination of leeks and carrots
Authors: PETCH G. M. , MAUDE R. B. , BUJALSKI W. , NIENOW A. W. 
Published: February 2008

SummaryThree batches of leek seeds were osmotically primed successively in the same polyethylene glycol solution in a bubble column at a seed concentration of 100 g/litre for seven days at 15°C. Three batches of carrot seeds were similarly primed in a separate solution for six days at 15°C. The concentration of microorganisms in the solutions increased rapidly during priming of the first seed batch for both seed types, but increases during priming of the second and third batches were small. The seeds were the main source of the microorganisms; priming reduced the numbers of colonies of filamentous fungi and increased those of bacteria and yeasts. The priming treatments improved the percentage germination of the three seed batches of primed carrots and reduced the mean time to germination in both species and the mean time to emergence in compost.Percentage emergence was not affected by priming except in the third batch of primed carrot seed. The presence of large numbers of microorganisms in the priming solutions did not greatly affect seed performance when the same osmoticum was used three times with leeks and twice with carrots. Priming did not affect the number of abnormal seedlings.
Role of alternative pathway respiration in tomato roots attacked by Meloidogyne incognita
Authors: MOLINARI SERGIO 
Published: February 2008

SummaryThe effect of nematode infestation on the alternative pathway respiration of mitochondria isolated from resistant and susceptible tomato roots greatly depended on the oxidisable substrate tested. The percentage of alternative respiration in NADH, malate and succinate oxidation was markedly different between the resistant (Rossol) and the susceptible (Roma VF) cultivars before infestation. Only the percentage of malate alternative oxidation in mitochondria from the resistant roots was influenced by nematode invasion. Conversely, attacked roots showed consistent variations in the content of mitochondria per unit fresh weight and in the phosphorylation efficiency (ADP/O) of the organelles. Expression of the alternative pathway (ρ' value) was found to be unchanged in intact roots and isolated mitochondria six days after nematode inoculation.
A key for the stages of development of potato (Solatium tuberosum)
Authors: JEFFERIES R. A. , LAWSON H. M. 
Published: February 2008

SummaryA key is presented to describe stages of development and growth of the potato (Solanum tuberosum L.). The code is divided into seven principal stages: seed germination and emergence, tuber dormancy, tuber sprouting, emergence and shoot expansion, flowering, tuber development, and senescence. Each of these is subdivided into secondary stages. Flowering and tuber development stages can be concurrent with the other stages to enable the separate description of the development of these organs. The practical uses of the key are discussed.
Modelling damage on maize by the European Corn Borer, Ostrinia nubilalis
Authors: LABATTE J. M. , GOT B. 
Published: February 2008

SummaryThe European Corn Borer (ECB), Ostrinia nubilalis Hbn. (Lepidoptera: Pyralidae), is a major pest of maize in many countries. Yield losses caused by larvae of this insect depend mainly on the extent of cavity damage, the timing of tunnelling, and their within‐plant distribution. To describe these factors, a mechanistic model of cavity appearance is proposed here. It takes into account the main biological processes which determine damage. These are the development, mortality and within‐plant distribution of the ECB larvae. The model has been estimated and tested on field data collected at INRA‐Versailles in France. Model fittings showed that (i) creation and lengthwise extension rates of cavities per larva depend on location and instar of the larvae, and that (ii) only instars 4 and 5 make cavities. This model described, with a high precision level, the appearance and lengthwise extension of cavities over time and their within‐plant distribution for two maize varieties, several infestation dates and levels, and various climatic sequences.
Influence of the green spruce aphid on defoliation and radial stem growth of Sitka spruce
Authors: DAY K. R. , McCLEAN S. I. 
Published: February 2008

SummaryPremature abscission of older Sitka spruce foliage on trees within forests in Northern Ireland was compared with green spruce aphid population levels 2 to 3 months earlier. Each aphid has a lower relative impact on needle loss at higher aphid population density; nevertheless, more aphids on a tree results in greater rates of needle loss. Evidence from horizontal stem increment sequences suggested that aphid feeding inhibited incremental growth, and that this inhibition might be delayed for up to two field seasons. However, the effect of aphids on stem growth in most years and on most trees seems relatively small compared with the potential of other tree‐or year‐specific processes.
Effect of annual and/or biennial burning of seed alfalfa stubble on populations of alfalfa weevil and pea aphid
Authors: SCHABER B. D. , ENTZ T. 
Published: February 2008

SummaryThe effects of five burning treatments of alfalfa (Medicago sativa L.) stubble combined with two insecticide treatments on populations of alfalfa weevil, Hypera postica (Gyllenhal), and the pea aphid, Acyrthosiphon pisum (Harris) were evaluated over an eight year period. The effects of the burn treatments were dependent on insect species, time of burn and year. Immature alfalfa weevil population levels were significantly reduced by the burn‐every‐autumn treatment in 3 of the 8 years, in 2 out of 8 years by the burn‐e very‐spring treatment, and by the alternate‐year‐burn treatment in 1 out of 4 years. Burning had little or no effect on pea aphid populations.
The economics of reduced‐rate insecticide applications to control aphids in winter wheat
Authors: MANN B. P. , WRATTEN S. D. , POEHLING M. , BORGEMEISTER C. 
Published: February 2008

SummaryApplications of pirimicarb and fenvalerate at full‐rate and at a range of reduced dosages were applied on fields of winter wheat between 1983 and 1988 in West Germany. The relative effects of these treatments on the control of cereal aphids varied according to the growth stage at which spraying took place and the size of the aphid populations. The economic profitability of these treatments depended on the extent of post‐treatment recovery of the aphid populations, the cost of control and the crop value.Under certain circumstances the high efficiencies of commonly‐used insecticides at full dose‐rate are not necessary to gain effective aphid control economically; a better return can be made by reducing the quantity of active ingredient per hectare.
The susceptibility of tubers of potato cultivars to black dot (Colletotrichum coccodes (Walk.) Hughes)
Authors: READ P. J. 
Published: February 2008

SummaryIn experiments with commercial seed of different cultivars at Rothamsted and Woburn, Bedfordshire in 1985 – 88 the severity of black dot on daughter tubers at harvest differed between cultivars. The disease was most severe on Desiree tubers. Amounts of disease were similar at both sites in 1986 – 88 but in 1985 it was more severe at Woburn than at Rothamsted.Disease‐free seed of 12 (1987) or 15 (1988) cultivars were planted in experiments at Rothamsted (inoculated with Colletotrichum coccodes or not) and at Mepal, Cambridgeshire (not inoculated) and black dot assessed at harvest in October 1987 and in September and October 1988. There were significant differences in the amount of disease on different cultivars and the order of severity was similar at the two sites, on the two harvest dates in 1988 and in both years. Desiree, Maris Piper, Maris Peer and Record were amongst those cultivars severely affected whereas Cara, Pentland Crown and Romano were least affected.Skin discoloration caused by black dot was more noticeable on white‐skinned than red‐skinned cultivars and was severe on the Dutch cultivars Estima, Marfona, Santé and Wilja.
Improvement of persistence and yield of Italian ryegrass (Lolium multiflorum) through pesticide use
Authors: CLEMENTS R. O. , BENTLEY B. R. , MURRAY P. J. , HENDERSON I. F. 
Published: February 2008

SummaryThe present two field experiments, involving plots of Italian ryegrass sown in 1976, 1980 and 1984 confirmed results of earlier work in which the yield and persistence of Italian ryegrass was greatly increased by the application of pesticide. A range of pesticide treatments were used. The responses to application of permethrin applied three times per year average 8% for the three years of the first experiment and 5% for the five years of the second experiment. Such responses appeared cost‐effective, but the overall environmental impact of such applications is not known.
Association of soybean root mycoflora with root modulation, root necrosis and plant fresh weight
Authors: FORBES G. A. , DAVET P. 
Published: February 2008

SUMMARYFungi were isolated from soybean plants in ten fields in south‐west France. Correspondence analysis (COA) was used to find associations among taxa (species, genera, groups) and sampling units (i.e. one field at one sampling date). The first axis of the COA demonstrated a dominant sampling date effect; the second indicated an association among certain sampling units and specific taxa. Regression analysis of COA coordinate values indicated that fields with high relative isolation frequencies of Fusarium spp., F. oxysporum and ‘other species’ (mostly Chaetomium spp. and sterile fungi) were characterised by greater plant fresh weight and nodule number and lower ratings for root necrosis. Cylindrocarpon spp., Cephalosporium spp. and F. solanihad high relative isolation frequencies in fields with lower plant weight, lower nodule number and higher root necrosis ratings. The relative importance of fungal taxa was also related to soil type.
Infective behaviour and aphid‐transmissibility of Italian isolates of potato virus Y in tobacco and peppers
Authors: MARTE M. , BELLEZZA G. , POLVERARI A. 
Published: February 2008

SUMMARYWhen mechanically inoculated to susceptible tobacco (Nicotiana tabacum L.) cultivars, nine isolates of PVY from Umbria (Central Italy) and two from Southern Latium gave rise to rapid systemic infection which developed within 6–8 days after inoculation. Systemic spread of the same isolates was slower, or much slower, in infected pepper (Capsicum annuum L.) cultivars, 8–14 days for Southern Latium isolates and 20 ‐ 35 days for Umbrian ones. Aphid (Myzus persicae)‐moculation of pepper and tobacco plants with two of the Umbrian and one of the Southern Latium isolates confirmed the results from sap‐transmission and showed that fewer inoculated pepper plants become infected, especially with Umbrian isolates. In agreement with the data on systemic spread, aphid‐acquisition trials indicated that tobacco plants became efficient PVY sources for vectors 6–8 days after inoculation with either group of isolates. Peppers became efficient acquisition hosts 8–15 days after inoculation with Southern Latium isolates but not until 22–45 days after inoculation with Umbrian ones. Southern Latium isolates induced more severe symptoms in pepper cultivars than Umbrian isolates did. One of the Southern Latium isolates was able to systemically infect the resistant pepper cv. Yolo Y, which was never infected by the Umbrian isolates. The Umbrian isolates tested seem to be better adapted to tobacco than peppers, while Southern Latium ones are well adapted to both.
A time‐course study of early establishment stages of parasitic angiospermStriga asiaticaon susceptible sorghum roots
Authors: RAMAIAH K. V. , CHIDLEY V. L. , HOUSE L. R. 
Published: February 2008

SUMMARYA time‐course study of the early establishment stages ofStriga asiaticawas carried out on a susceptible sorghum hybrid, CSH 1, using polyethylene bags and whole‐root clearing and staining techniques. PreconditionedStrigaseeds were applied to different aged segments of primary root but the results did not differ for these different aged segments. Most of theStrigaseeds (63%) germinated within 24 h of inoculation on the host roots. The attachment ofStrigaradicles to host root was rapid and it occurred between 36 and 48 h after inoculation. Only 9% of the germinatedStrigaseeds attached to the host root but 65% of these attachments successfully penetrated through the epidermis and entered the host cortex within 72 h. Penetration through the cortical cells was difficult; only 17% of attachments were able to reach the endodermis. Penetration took from 12 to 43 h after the first appearance of haustorial cells in the cortex; a total of 84 to 120 h after inoculation on the host root. Penetration through the endodermis and establishment on the host stele was relatively easier, as most of the haustoria reaching the endodermis were able to establish on the host stele. But this is a slow process taking a minimum of 24 h, and a maximum of 60 h after first contact of haustorial cells with the endodermis. The minimum time taken from inoculation of ungerminatedStrigaseed on the host root to establishment is about 108 h. The results are discussed in relation to published reports on other parasitic species such asAgalinis purpurea.
Influence of growth form of Arena fatua L. on the growth and yield of Triticum aestivum L.
Authors: ROONEY JOY M. 
Published: February 2008

SUMMARYIn a field experiment, all components of winter wheat grain yield, except grain number per ear, were reduced by wild‐oat competition, and more so by a prostrate form of wild‐oat than by an upright form. The prostrate form, ‘Churston’, shaded the crop at anthesis. Although there were no significant differences in photosynthetic activity in the flag leaves of wheat at saturating light intensities during the later stages of grain filling, it is likely that differences in growth form, height, weight and area of these two forms of wild‐oat, competing principally for light, accounted for their different effects on wheat grain yield.
The assessment of two barley starch mutants as potential parents in a malting quality breeding programme
Authors: SWANSTON J. S. 
Published: February 2008

SUMMARYGrain and malt quality parameters were assessed in the barley starch mutants Waxy Hector, characterised by high levels of amylopectin, and Chalky Glenn, which has lines of cleavage across the large starch granules. Results were compared with those of their parental cultivars and suggested differences in the contribution of endosperm cell walls to milling energy. Although hot water extracts were not improved, other components, especially those associated with the fractured starch mutant, could be used in breeding programmes to improve aspects of quality, if they could be disassociated from deleterious effects of the starch mutation, e.g. poor grain filling.
The use of DNA markers to estimate the extent and nature of genetic variability in Solatium tuberosum cultivars
Authors: POWELL W. , PHILLIPS M. S. , McNICOL J. W. , WAUGH R. 
Published: February 2008

SUMMARYHigh levels of DNA polymorphism were detected in 27 Solanum tuberosum cultivars examined. Combinations of at least two c‐DNA clones have been identified which in conjunction with EcoRI allow important UK potato cultivars to be characterised by their molecular profiles. The widely grown North American cultivar Russett Burbank was also successfully fingerprinted. Estimates of genetic diversity based on restriction fragment length polymorphism (RFLP) data indicate the important role that wild potato species and exotic germplasm have played in the development of the cultivars studied. A graphical method for simultaneously highlighting similarities and differences between genotypes for individual hybridising fragments is presented. This approach is particularly useful in identifying and recording fragments which are unique to certain genotypes.Two potato cultivars: Fiona and Morag produce unique RFLP profiles when digested with EcoRI and EcoRV and probed with a flax ribosomal DNA sequence. Both Fiona and Morag possess incomplete or partial (quantitative) type resistance to G. pallida which was transferred from S. vernei. The preferential transmission of the r‐DN A fragments from S. vernei may indicate that this locus is associated with genetic factors controlling resistance to G. pallida.
The combined effects of a newly designed dibber drill, irrigation and seed covering treatments on lettuce and calabrese establishment
Authors: FINCH‐SAVAGE W. E. , RAYMENT M. , BROWN F. R. 
Published: February 2008

SUMMARYA comparison was made between seedling establishment following sowing with the Mk2 dibber drill and a conventional coulter drill at three sowing occasions with both lettuce and calabrese. Different seed covering materials used to cover dibber‐drilled seed were also compared.With lettuce, the rate and uniformity of seedling emergence and the numbers of seedlings emerging were greater following sowing with the dibber drill than with the coulter drill. Seedling establishment was further improved with irrigation especially when seeds were sown with a small quantity of the hydrophillic polymer, Alcosorb, which avoided associated problems of increased soil impedance. Alcosorb was a more effective seed cover than a peat and vermiculite mix and better suited for mechanical metering. Results indicate that the dibber drill can be considered as a realistic and cheaper alternative to transplanting for establishing later‐season lettuce crops. With calabrese, however, percentage seedling emergence on all dibber‐drilled plots was lower than that on plots sown with the coulter drill. This result may have been due to seed‐coat damage caused as seeds are plunged into the soil during sowing with the dibber drill.
Transmission of plant viruses by fungi
Authors: ADAMS M. J. 
Published: February 2008

SUMMARYThe evidence for the mechanisms involved in virus transmission by fungi is reviewed in relation to the non‐persistent and persistent categories usually recognised.Non‐persistent transmission by Olpidium spp. has been little studied in the last 20 years, but appears to depend on adsorption of virus to the outside of the fungal zoospores. This seems to be under the genetic control of both the virus (via its coat protein) and the vector. Such viruses are not transmitted in the fungal resting spores. The route by which the virus is transferred from the vector to the host may involve uptake into the zoospore but this deserves further study.Persistent transmission by Olpidium, Polymyxa and Spongospora spp. is less well characterised. Some of the evidence used for its support is inconclusive. The viruses are probably always carried inside zoospores, and they also persist in the fungal resting spores. Transmission depends on the genome of the vector and the virus, but not exclusively on the virus coat protein.
Variation in virulence to dry beans, soybeans and maize among isolates of Rhizoctonia solani from beans
Authors: PHILLIPS A. J. L. 
Published: February 2008

SummaryThe relative susceptibility of dry beans (Phaseolus vulgaris), soybeans and maize to anastomosis group 4 isolates of Rhizoctonia solani was determined in greenhouse experiments. Large variations in virulence were found among 30 field isolates. This variation was not due to differential reductions in isolate virulence during axenic culture. There was considerable variation among isolates from within the same field but variability within isolates was small. Twelve of 30 isolates of R. solani were highly virulent to dry beans and soybeans, while the others were of low virulence. Soybeans were more susceptible than dry beans to both pre‐emergence mortality and hypocotyl disease. No isolates were highly virulent to maize. The importance of using isolates with a high level of virulence for testing soybean cultivars for resistance to Rhizoctonia disease is stressed.
Effects of Caenorhabditis elegans (Nematoda: Rhabditidae) on the spread of the bacterium Pseudomonas tolaasii in mushrooms (Agaricus bisporus)
Authors: GREWAL P. S. 
Published: February 2008

SummaryThe effects of mass‐produced saprobic rhabditid nematodes, Caenorhabditis elegans on the spread of the bacterial blotch pathogen, Pseudomonas tolaasii, were studied in mushroom growth chambers. C. elegans significantly reduced the intensity of blotch on sporophores. Repeated isolations of the bacterial flora from the gut of C. elegans recovered from mushroom sporophores during cropping, revealed the presence of Pseudomonas fluorescens biovar reactans. All the isolates of P. fluorescens biovar reactans isolated from nematodes were antagonists of P. tolaasii. C. elegans produced much larger populations in monoxenic cultures with P. fluorescens biovar reactans than with P. tolaasii. It is suggested that as C. elegans selects P. fluorescens biovar reactans rather than P. tolaasii as a food substrate it probably spreads the antagonist in the mushroom crop and may contribute to the control of bacterial blotch.