bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact of the field slug Deroceras reticulatum on establishment of ryegrass and white clover in mixed swards
Authors: GLEN D. M. , CUERDEN R. , BUTLER R. C. 
Published: February 2008

SummaryThe relationship between numbers of Deroceras reticulatum and the establishment of ryegrass cv. Melle and white clover cv. Milkanova was studied on a mini‐plot experiment. Assessments 12 and 33 days after sowing showed that Deroceras reticulatum had a proportionally greater impact on survival and growth of clover than on ryegrass. Slugs had no apparent effect on numbers or growth of three species of broad‐leaved weeds (Senecio vulgaris, Cardamine hirsuta and Epilobium sp.) which occurred in the field experiment. In pot experiments where seedlings of ryegrass together with one of three clover cultivars, with or without chickweed (Stellaria media), were exposed to Deroceras reticulatum, seedlings of white clover cv. Aran were less affected by slug grazing than cvs S184 or Milkanova. The presence of different clover cultivars did not significantly influence the impact of slugs on growth of ryegrass or chickweed, nor did the presence or absence of chickweed influence the effect of slugs on ryegrass and clover seedlings. Slugs had less impact on the growth of chickweed than on ryegrass or clover. Thus slug grazing would make clover less able to compete with chickweed as well as the other weeds found in the mini‐plot experiment.
A non‐destructive determination of leaf chlorophyll in Vitis vinifera
Authors: FANIZZA G. , GATTA C. DELLA , BAGNULO C. 
Published: February 2008

SummaryA portable leaf greenness meter (SPAD‐501) has been used to provide a rapid and non‐destructive measurement of leaf chlorophyll in Vitis vinifera. Leaf extracted chlorophyll was related linearly to SPAD readings. It is suggested that separate linear equations should be developed for each cultivar so as to maximise the accuracy of estimating leaf chlorophyll content as a function of SPAD readings.
The influence of intercropping with Allium on some insect populations in potato (Solatium tuberosum)
Authors: POTTS MICHAEL J. , GUNADI NIKARDI 
Published: February 2008

SummaryTwo field experiments were conducted in West Java, Indonesia to investigate the effects on insect populations in a potato crop of intercropping with Allium cepa or A. sativum. Intercropping reduced populations of Myzus persicae, Aphis gossypii and Empoasca spp. when less than 0.75 m separated the potato plants and Allium spp. Leaf damage to potato by Henosepilachna sparsa was also reduced at this spacing; but populations of Thrips palmi or T. parvispinus were increased. The implications of these trends are noted.
Effects of Aphis fabae and Uromyces viciae‐favae on the growth of a susceptible and an aphid resistant cultivar of Vicia faba
Authors: PRÜTER C. , ZEBITZ C. P. W. 
Published: February 2008

SummaryDamaging effects of either black bean aphid (Aphis fabae), broad bean rust (Uromyces viciae‐fabae), or the combination of both were investigated on a susceptible (cv. Diana) and an aphid resistant (cv. Bolero) cultivar of Vicia faba. When compared with rust, aphids caused greater reductions of root dry weight, shoot dry weight, leaf area, and mean relative growth rate. The mean unit leaf rate was also reduced whereas the leaf area ratio was not affected. The damage caused per aphid was highest on the susceptible cultivar. Rust induced damage did not differ between the cultivars. Concomitant infestation with both pests only resulted in additive damage. The population development of aphids was delayed on partially resistant plants. High temperature and rust infection reduced the total number of aphids the plants were able to support but not the level of resistance. Thus the specific damaging effect per aphid was increased.
Losses in productivity of subterranean clover swards caused by sowing cucumber mosaic virus‐infected seed
Authors: JONES R. A. C. 
Published: February 2008

SummaryField trials were done in 1988 ‐ 89 at two sites to examine the effects of sowing seed stocks in which a low proportion (1.6–7.0%) of the seed was carrying cucumber mosaic virus (CMV) infection (= infected seed) and the subsequent CM V spread that results, on the productivity of swards of subterranean clover cvs Esperance, Green Range and Karridale. Except in irrigated plots of cv. Green Range, a variable proportion of the CMV‐infected seedlings always failed to establish, so sowing infected seed normally resulted in plots containing fewer or far fewer seed‐infected plants than expected. The rate of virus spread by aphids was faster and resulted in more extensive infection at maturity when the plots contained more seed‐infected source plants. In two irrigated trials at South Perth, in which healthy and infected seed of cvs Esperance and Green Range was sown, CMV spread was extensive. When the plots were left undefoliated, herbage dry wt yields were decreased by 12 – 30% and seed yields by 53 – 64% due to infection. When they were mown, the herbage dry wt losses recorded were 17 – 24%. In three trials at Mt Barker sown with healthy and infected seed, extensive spread of CMV occurred with cv. Green Range but not with cvs Esperance and Karridale. With cv. Green Range, losses of 25 – 28% in herbage dry wt were recorded inside CMV‐affected patches in mown or grazed plots, while losses were up to 13% when herbage was sampled at random. Seed yield losses were 40–42% and 53% in infected mown and undefoliated cv. Green Range plots, respectively. In the mown or grazed plots of cvs Esperance and Karridale, herbage dry wt losses recorded were up to 7% while seed yield losses were 9 – 16% in mown and 9% in undefoliated plots.The mean wt/seed of seed harvested from mown plots of cvs Green Range and Karridale sown with infected seed was 8–12% less than that of seed from mown control plots. CMV was detected in seed harvested from undefoliated cv. Green Range plots and mown plots of cvs Green Range and Karridale sown with infected seed but levels of seed infection with the mown plots were 3–5 times less than in the seed sown.Field trials were done at two sites in 1987 – 90 to examine the persistence of CMV in subterranean clover swards. CMV infection was established in 1987 and the plots were grazed in subsequent years. At Badgingarra, infection gradually decreased with little CMV being recovered by 1990. At Mt Barker, recovery of CMV was relatively poor in 1988 and even poorer in 1989, but there was some resurgence of CMV infection in 1990.
The use of monoclonal antibodies to detect beet mild yellowing virus and beet western yellows virus in aphids
Authors: SMITH H. G. , STEVENS M. , HALLSWORTH P. B. 
Published: February 2008

SummaryInformation on infectivity of the aphids which invade sugar beet root crops each Spring is required for forecasting incidence and providing advice on control of virus yellows. Monoclonal antibodies, produced in the USA to barley yellow dwarf virus (BYDV) and in Canada to beet western yellows virus (BWYV), were used to distinguish between sugar‐beet‐infecting strains of the luteovirus beet mild yellowing virus (BMYV), and the non‐beet‐infecting strains of the closely‐related BWYV in plant and aphid tissue. Totals of 773 immigrant winged Myzuspersicae and 124 Macrosiphum euphorbiae were caught in water traps in a crop of sugar beet between 25 April and 5 August 1990. Using the monoclonal antibodies and an amplified ELISA, 67%M. persicae and 19%M. euphorbiae were shown to contain BWYV; 8%M. persicae and 7%M. euphorbiae contained BMYV. In studies with live winged aphids collected from the same sugar beet field during May, 25 of 60 M. persicae and two of 13 M. euphorbiae transmitted BWYV to the indicator host plant Montia perfoliata; two M. persicae and two M. euphorbiae transmitted BMYV. In another study three of 65 M. persicae and one of three M. euphorbiae in which only BWYV was detected, transmitted this virus to sugar beet.
A screening technique to evaluate pigeonpea for resistance to Rotylenchulus reniformis*
Authors: SHARMA S. B. , ASHOKKUMAR P. 
Published: February 2008

Summary Rotylenchulus reniformis is one of the most important nematode pests of pigeonpea. A simple greenhouse technique has been developed to aid evaluation of pigeonpea genotypes for resistance to R. reniformis. In greenhouse pot experiments, eggsacs of R. reniformis in pigeonpea (cv. ICPL 87) roots were counted by eye and with the aid of a stereoscopic microscope at 15, 30 and 45 days after seedling emergence in soils infested with various numbers of vermiform R. reniformis. Seedlings were rated for the number of eggsacs per root system on a one (no eggsacs) to nine (more than 50 eggsacs) scale. Eggsac ratings were more uniform when roots were evaluated at 30 – 45 days than at 15 days and an inoculum of 15 to 30 individuals/cm3 soil also helped reduce variability. Eggsacs were not easily visible without the aid of a stereoscopic microscope. Of the 14 stains tested, exposure of nematode‐infected roots to 0.25% trypan blue for three min was effective in staining the eggsacs blue without staining the roots. Using the stain, the assessment of infestation by R. reniformis was equally accurate with or without the aid of a stereoscopic microscope. Exposure of eggsacs to trypan blue enhanced the emergence of juveniles from the eggsacs.
The hybridisation of somatically chromosome‐doubled dihaploid potatoes with tetraploid cultivars and the use of doubled dihaploids in genetic analysis of Solatium tuberosum
Authors: De M. J. , FLEMING M. L. M. H. 
Published: February 2008

SummaryThree doubled dihaploid potatoes were hybridised with six tetraploid cultivars and the offspring examined for commercially important characters. Doubled dihaploids used as parents did not reduce the within progeny phenotypic variation for most characters below that found in material produced by intercrossing heterozygous tetraploids. They could however prove useful for improving some characters in a breeding programme.The products of the hybridisations were used to examine the genetic control of discrete variables such as tuber skin pigmentation, tuber flesh colour, and skin russetting. Doubled dihaploids were found to be useful for such studies because they have only three out of the five possible tetraploid genotypes. Presence or absence of red tuber skin in the progenies of cv. Désirée was concluded to be due to the segregation of a dominant major gene which was simplex in the parental cultivar. The yellow flesh of Desiree was found to be recessive. On the hypothesis that russet skin was due to three complementary dominant genes, possible genotypes of the doubled dihaploids and cultivars could also be deduced.
Development of carrot inbreds with resistance to carrot fly using a single seed descent programme
Authors: ELLIS P. R. , SAW PAMELA L. , CROWTHER T. C. 
Published: February 2008

SummaryTwo carrot cultivars, ‘Sytan’ and ‘Long Chantenay’, representing commercially important carrot types and selected for their partial resistance to the carrot fly (Psila rosae) were crossed as the basis for a single seed descent programme. The resulting F1 progeny were mass pollinated to produce an F2 generation and approximately 2000 plants were raised from this segregating family in the glasshouse in 1981. By careful choice of sowing date and glasshouse temperatures it was possible to stimulate the plants to flower within 10 months. Individual king umbels were enclosed within bags and pollinated with blowflies. Resulting seed was sown in pots in the following August and the process of seed production repeated in a 12 month cycle. Each inbred line was selfed in this way over three generations until the F5 stage. Stocks of seed were then multiplied. A total of 753 inbreds were produced by 1987. The vigour of each inbred was evaluated in glasshouse tests and the level of chlorogenic acid was determined by a fluorescence technique. The most vigorous lines with the lowest levels of chlorogenic acid were tested in field experiments against carrot fly at Wellesbourne. Nine inbreds with promising agronomic quality and moderate resistance to carrot fly were selected and seeded. These nine lines were submitted to seed companies with the aim of developing new cultivars of carrot.
Effects of straw disposal and tillage on spread of barley yellow dwarf virus in winter barley
Authors: KENDALL D. A. , CHINN N. E. , SMITH B. D. , TIDBOALD C. , WINSTONE L. , WESTERN N. M. 
Published: February 2008

SummaryThe effects of straw baling or incorporation, combined with ploughing, non‐inversion tillage, or direct drilling on the incidence of barley yellow dwarf virus (BYDV), were investigated in plots of winter barley. Virus infection was more prevalent after ploughing (> 40% of the plot area damaged) than after non‐inversion tillage (9 – 24%) or direct drilling (< 3%). For each cultivation method, more infection was associated with straw baling than with straw incorporation. There was a strong negative correlation between plot yields and the incidence of BYDV(r= ‐0.87).Monthly pitfall sampling of non‐specific aphid predators showed that the population activity of several taxa (e.g. Linyphiidae, and the larger species of adult and larval Carabidae and Staphylinidae) declined for a short period in autumn‐winter following cultivation. The overall treatment‐ranking for numbers of predators in autumn (direct drilled > non‐inversion > ploughed) was the opposite of subsequent virus infection. The possible roles of aphid predators and other biological mechanisms in determining the observed effects on BYDV, are briefly discussed.
The effects of nitrogen and fungicide on cereal aphid population development and the consequences for the aphid‐yield relationship in winter wheat
Authors: ZHOU X. , CARTER NICK 
Published: February 2008

SummaryIn a field trial, done over two seasons, nitrogen and fungicide inputs to winter wheat were varied to obtain a range of yields to study the effects on aphid population development and the aphid‐yield loss relationship. In the first year, the maximum density of Metopolophium dirhodum and total aphid index were significantly higher in the plots receiving the largest amount of nitrogen but there were few other consistent effects on aphid population development. In the second year there were no significant effects of either nitrogen or fungicide on aphid population development. Mean yields were high in 1987 and 1988 (7.0 and 8.5 t/ha respectively) with less than a 2 t/ha range in either year. There were no significant effects of aphids on yield in the first year but in the second, aphids caused a significant reduction. Damage per aphid unit did not change with increase in yield. The use of this approach in determining pest‐yield loss relationships is discussed.
Further evidence that resistance in raspberry to the virus vector aphid, Amphorophora idaei, is related to the chemical composition of the leaf surface
Authors: ROBERTSON G. W. , GRIFFITHS D. W. , BIRCH A. N. E. , JONES A. T. , McNICOL J. W. , HALL JOANNE E. 
Published: February 2008

SummaryIn an approach to understand the mechanism(s) of resistance in raspberry to infestation by the aphid Amphorophora idaei, progeny plants segregating for the A. idaei resistance gene, A10, were bioassayed and dichloromethane extracts from the leaf surface were examined by capillary column gas chromatography (GC). No single GC peak was detected that was present in only the resistant progeny plants. Nevertheless, thirteen compounds present in all samples were quantified and identified by mass spectrometry. They were of four major classes; straight chain hydrocarbons, acetic acid esters of long chain alcohols, tocopherols and triterpenoid compounds, including α and β amyrin. Several of these compounds were not recorded previously in raspberry leaves. Linear discriminant analysis, applied to the standardised chromatographic data in an attempt to relate chemical composition to resistance, successfully partitioned 24 of the 26 plants into resistant and susceptible types as determined by bioassay. These data provide further evidence that resistance in raspberry to A. idaei is related to the chemical composition of the leaf surface.
Selection for resistance to clubroot (Plasmodiophora brassicae) in marrowstem kale (Brassica oleracea var. acephala L.)
Authors: BRADSHAW J.E. , WILLIAMSON CYNTHIA J. 
Published: February 2008

SummaryNinety‐six cultivars of Brassica oleracea were screened for clubroot resistance in a seedling test using two populations of Plasmodiophora brassicae. The most resistant cultivars were kales. Sixteen resistant marrowstem kale cultivars of diverse geographical origin were used to start a selection programme for clubroot resistance. Four generations of selection, involving single plants, half‐sib and full‐sib families, reduced a disease index averaged over six clubroot populations from 41.2 to 12.5. This was lower than the most resistant cultivar in the original population, cv. Mixti 28.8, and as good as a German landrace of cabbage noted for its resistance, Bohmerwaldkohl 10.5. In comparison, the mean of five kale controls, cvs Bittern, Canson, Condor, Kestrel and Merlin, was 61.1 and the value for the most susceptible control, cabbage cv. Septa, was 89.3.In the final assessment, there were no clubroot population x B. oleracea genotype interactions and in the initial assessment of cultivars there were only small interactions which could be removed by an angular transformation of the data. It was concluded that a high level of non‐differential resistance had been achieved and that it may prove durable. It was also concluded from a small field trial that this level of resistance would prevent serious yield losses in practice.
Thermal time assessment of suitable areas for navy bean (Phaseolus vulgaris) production in the UK
Authors: DODD M. 
Published: February 2008

SummaryIn field trials at eight sites throughout the UK the mean thermal time requirement for navy beans from sowing to harvest for a standard cultivar, Marcus, was 2069 Ontario Heat Units (OHU). Low level plastic covers increased the range of warm environments at one site and gave a mean thermal time required of 2098 OHU.Analysis of daily air temperatures from six weather stations throughout the UK over a 29 year period, showed a 14 day possible planting period on the south coast of England, but gave a high probability of crop failure in Scotland.Maps of England and Wales indicating the probability of achieving 2000 OHU were produced from 5 km grid point temperatures. Less than 2% of the land had more than a 60% chance of receiving 2000 OHU under the present climate, however this area increased to 70% with a mean temperature rise of 1.5°C. Although 2000 OHU is often used as the thermal time requirement of navy beans, these trials showed that it may be more accurate to use the higher figure of 2087 OHU from sowing to harvest, and restrict the use of 2000 OHU to the period between emergence and harvest. When the map was redrawn using 2087 OHU and current climate, no parts of England and Wales showed a reasonable chance of growing the present cultivars of navy beans.
Studies on the patterns of nitrogen uptake and translocation to the grain of winter barley intended for malting
Authors: CARRECK N. L. , CHRISTIAN D. G. 
Published: February 2008

SummaryIn five experiments carried out between 1987 and 1989, crops of winter barley were grown under a range of agronomic treatments to study the way the treatments influenced the patterns of nitrogen uptake, dry matter production, translocation of assimilates and malting quality.Rate and timing of nitrogen fertiliser had large effects. Increased and late applications invariably increased nitrogen concentration in the grain by affecting the partitioning of nitrogen between the vegetative and reproductive parts of the plant. Foliar fungal diseases also affected nitrogen partitioning, apparently by interfering with the transport of stored nitrogen to the developing grain.Seasonal influences, especially rainfall during the grain filling period, were found to have profound effects on the pattern of change in ear and grain nitrogen concentration, and hence malting quality. The ability to predict final grain nitrogen concentration from measurements made earlier in the season is not therefore likely to be feasible.
A computer‐based advisory system for cereal aphids‐field‐testing the model
Authors: MANN B. P. , WRATTEN S. D. 
Published: February 2008

SUMMARYA previously developed computer‐based interactive model which can aid farmers in the control of summer aphids on winter wheat was tested in field trials carried out from 1985 to 1988. These trials showed that the model performed very well when compared with other popular types of advice available. Economic comparison of the model with current and previous ADAS advice showed that the model performed as well or better. It also had the advantage that it used the economics of the situation, as well as the size of the pest population, in calculating advice.
Disease in wheat genotypes naturally infected with Gaeumannomyces graminis var. tritici
Authors: PENROSE L. D. J. 
Published: February 2008

SUMMARYWheat genotypes consisting of seven homozygous lines and 40 segregate families were studied at two sites naturally infested with the take‐all pathogen, Gaeumannomyces graminis var. tritici. The numbers of seminal and coronal roots infected with G. graminis and other root pathogens were recorded. The genotypes differed in infection with G. graminis, with little evidence of genotype × environment interactions. The incidence of G. graminis and Rhizoctonia solani was negatively associated, but the association did not greatly influence differences between wheats in infection with G. graminis. The distribution of R. solani was negatively associated with the severity of take‐all at only one site. Of symptoms of infection with G. graminis, wheat genotypes differed most in incidence of deadheads, but differences were not consistent over environments, and were associated with earliness of maturity. Wheats differed more in expression of disease than in infection with G. graminis.The course of disease was deduced from associations between the incidence of pathogens and components of plant growth and yield. G. graminis was the dominant pathogen at both sites, and caused a yield loss of 0–15% at one site, and an average 62% loss at the other. More components of yield were affected where disease was most severe.
A variant of the satellite RNA of groundnut rosette virus that induces brilliant yellow blotch mosaic symptoms in Nicotiana benthamiana
Authors: KUMAR I. K. , MURANT A. F. , ROBINSON D. J. 
Published: February 2008

SUMMARYSome Malawian cultures of groundnut rosette virus (GRV) give rise to variants that, although still causing symptoms of the chlorotic type of rosette in groundnut, induce brilliant yellow blotch mosaic symptoms, instead of the usual veinal chlorosis and mild mottle, in Nicotiana benthamiana. One such isolate (YB) induced the formation in infected plants of a 0.9 kbp dsRNA having extensive sequence homology with molecules of similar size in other naturally occurring isolates of GRV. These dsRNA molecules were shown to be double‐stranded forms of single‐stranded satellite RNA molecules. Experiments in which the satellite was removed from and restored to isolate YB, or exchanged with those from other GRV isolates, showed that it carries the determinant for yellow blotch mosaic symptoms. Plants inoculated with the 0.9 kbp dsRNA (denatured or undenatured) developed yellow blotch mosaic even when the satellite‐free GRV helper was not inoculated until 11 days later. The satellite RNA is therefore a very stable molecule. Prior infection of N. benthamiana with a GRV isolate containing a normal form of the satellite protected against expression of yellow blotch mosaic symptoms when the plants were later inoculated with isolate YB, whereas prior infection with satellite‐free isolates did not. This provides a simple method of determining whether a GRV isolate has an associated satellite RNA. The YB satellite seems to be a newly recognised variant additional to those known to cause the chlorotic, green and other forms of groundnut rosette disease.