bluuebunny/crossref_metadata_2025_split huggingface dataset:
A study of spatial distribution and population dynamics of two sympatric species of trichodorid nematodes
Authors: ALPHEY T. J. W. 
Published: February 2008

SUMMARYThe spatial distribution and population dynamics of Trichodorus primitivus and Paratrichodorus pachydermus were studied at a Scottish nursery site in replicated plots. Each plot was split and half was fumigated with dichloropropene. The numbers of males, females and juveniles under Scots pine (Pinus sylvestris), grass/clover (Lolium perenne/Trifolium repens) and fallow in non‐fumigated and fumigated subplots were recorded at 10 cm intervals to a depth of 50 cm every 4 months for 3 years.In the non‐fumigated subplots the population densities of T. primitivus under each crop and the fallow soil were similar at the beginning and end of the experiment but P. pachydermus responded differentially, decreasing in fallow soils and increasing under pine. The ratios of adult: juvenile and male: female for the two species were not significantly affected by crop or sampling depth. T. primitivus was the more numerous species except under pine where P. pachydermus gradually became dominant during the study. Both species were present in all the depth samples but showed an aggregated distribution with different modal depths. The depth at which most P. pachydermus were found was shallower than for T. primitivus. Differences in the distribution and behaviour of the two species were found indicating how the two species could co‐exist or succeed each other.Fumigation with dichloropropene decreased the trichodorid populations to < 1 per 200 g soil to a depth of 50 cm. The relative development of the populations under the different crops and fallow soil were similar to those in non‐fumigated soils.
The effect of plant density, harvest date and method on the yield of seed and components of yield of parsnip (Pastinaca sativa)
Authors: GRAY D. , STECKEL JOYCE R. A. , WARD J. A. 
Published: February 2008

SUMMARYExperiments conducted over four years (1980–1983) with parsnip cv. Avonre‐sister examined the effects of plant density, harvest date and method on seed yield and the components of yield. In 1980, using the root‐to‐seed method, the yield of seed increased by 50% for an increase in plant density from 5.6 to 35 plants m‐2; the maximum yield at the optimum harvest date was 3015 kg h‐1. In the other three years, using the seed‐to‐seed method, seed yield increased to a maximum with an increase in plant density from c. 1 to 10 plants m‐2 but at higher densities yields were lower. At c. 10 plants m‐2, seed yields were 1567, 4029 and 1040 kg ha‐1, in 1981, 1982 and 1983, respectively, when harvested at the optimum time. An increase in plant density increased the number of non‐seeding plants in the population, reduced the number of umbels per plant and reduced the number of seeds per umbel. Mean seed weight was, in general, unaffected by plant density and so effects of density on yield reflected changes in seed numbers. Increasing the plant density increased the proportion of primary‐umbel seed. Maximum yields of seed were obtained from crops harvested at a seed‐moisture content of 50 to 70%, which occurred 46 ± 2·4 days after flowering. Delay in harvesting after this date led to a loss of yield of 33, 35, 139 and 32 kg ha‐1wk‐1 in 1980, 1981, 1982 and 1983, respectively. Plants cut, placed in the windrow to dry and then threshed gave similar yields to those harvested at the same time but dried in bins.
The presentation of treatment responses from block experiments after analysis of variance of transformed data
Authors: MORRIS G. E. L. 
Published: February 2008

SUMMARYMany types of data require transformation in order to satisfy the underlying assumptions of analysis of variance. When treatment responses are to be presented on the original measurement scale, and the experiment was arranged in blocks, there are at least two methods of doing so, namely the value that would have been expected if the treatment had been applied to all plots in the experiment and the value that would have been expected if there had been no block effects. These differ, because they correspond to different models, and the magnitude of their difference increases as the block‐to‐block variation increases. Examples are given to illustrate these differences for a range of commonly used transformations and the occasions on which the two methods should be used are discussed.
Reproductive biology and related host‐parasitoid interactions between the gypsy moth, Lymantria dispar and Glyptapanteles flavicoxis, a gregarious endoparasitoid*
Authors: HU CUI , BARBOSA P. , MARTINAT P. 
Published: February 2008

SUMMARYThe mean total progeny produced by female Glyptapanteles flavicoxis was significantly greater when the parasitoid attacked 4th instar gypsy moth rather than younger larvae. The development of parasitoids within older instars was faster than that in younger hosts. The proportion of female progeny was not altered by the host instar parasitised. The total reproductive output per female G. flavicoxis increased as the number of host larvae increased. However, since the reproductive output was spread among more available hosts, the reproductive output per host declined as the number of host larvae increased. There was no trend in the relationship between total progeny produced or the proportion of female progeny and the number of matings of parental females.
Mechanical aids to improve the speed and sensitivity of plant virus diagnosis by the biological test method
Authors: LAIDLAW W. M. R. 
Published: February 2008

SUMMARYModifications to a Pollahne leaf sap press are described which allow it to be used for bioassay purposes without risk of cross contamination. Constructional details are given for manual and automatic versions which utilise hot and cold water to sterilise and cool the working parts of the press. Two compressed air guns which are used together to inoculate indicator plants, are also described. The first incorporates carborundum powder into a jet of air and causes controlled wounding of plant epidermal cells to permit virus entry. The other applies sap inoculum as a finely divided spray to the wounded plants. The variables affecting the use of these guns are discussed. Improvements in sensitivity of 64 fold, compared to manual methods were obtained and potential to develop this to 500fold demonstrated.
Resistance in apple to shoot infection by Venturia inaequalis
Authors: JEGER M. J. , ALSTON F. H. 
Published: February 2008

SUMMARYEight apple genotypes, including cultivars and breeding selections resistant and susceptible to Venturia inaequalis on foliage, were screened for shoot infection and the development of wood pustules following inoculation of shoot tips of 1–year maiden trees in the greenhouse. Where genotypes were highly resistant in terms of foliar symptoms (cvs Prima and Gavin), no shoot infection was observed. Where genotypes were highly susceptible in terms of foliar symptoms, then shoot tissue was either resistant (cv. Shinko) or susceptible (cv. Starking). In one experiment, shoot tips were inoculated sequentially as shoots extended. No pustules developed where inoculations were made later than May. In a further experiment, two leaf internode positions were inoculated on one occasion. Pustules were only observed where inoculations were made above the youngest unrolled leaf. The results suggested that shoot tips were more susceptible during early extension growth of the shoot. Pustules were noted in abundance on petioles of susceptible cultivars, and these probably contributed to early leaf abscission.
The effects of the foliar fungicide pyrazophos on beneficial arthropods in barley fields
Authors: SOTHERTON N. W. , MOREBY S. J. , LANGLEY M. G. 
Published: February 2008

SUMMARYThe insecticidal properties of the foliar fungicide pyrazophos were investigated in autumn‐ and spring‐sown barley crops using several methods to estimate the density of non‐target arthropods and by using manipulative experiments. In autumn‐sown crops, pyrazophos significantly reduced densities of cereal aphid natural enemies relative to pre‐treatment levels compared to areas of crop that were left unsprayed. These significant differences persisted in most groups for over 45 days after treatment. Groups most affected were aphid‐specific predators, polyphagous predators, (Carabidae, Staphylinidae but not Araneae) and parasitoids. Insects known to be preferred food items of wild gamebird chicks and other non‐target groups such as the Collembola were also significantly reduced in density on plots sprayed with pyrazophos, the effects again persisting for over 45 days. Densities of beneficial and non‐target insects were also reduced in plots of spring barley sprayed with pyrazophos. However, the experimental design meant that levels of reductions were not significant for most arthropod groups.Removal of prey items (Drosophila pupae) placed in sprayed and unsprayed spring barley plots showed that the proportion predated was significantly lower on pyrazophos‐treated plots compared to those remaining unsprayed, the difference persisting for at least 7 wk after treatment. Removal of cereal aphids from colonies introduced to sprayed and unsprayed plots was also significantly lower on plots treated with pyrazophos. Difficulties of data interpretation associated with experimental design are discussed together with the consequences of the use of broad‐spectrum pesticides in I.P.M. programmes in cereals.
Effect of dodecanoic acid on the colonisation of sugar beet by aphids and the secondary spread of virus yellows
Authors: HERRBACH E. 
Published: February 2008

SUMMARYThe effect of dodecanoic acid, a behaviour‐controlling chemical which alters aphid feeding behaviour and virus transmission efficiency, was studied under field conditions. In a first experiment, dodecanoic acid reduced the level of natural colonisation of sugar beet by Aphis fabae. A second experiment revealed no significant influence of dodecanoic acid on the secondary spread of the semi‐persistent beet yellows virus and the persistent beet mild yellowing virus.
A comparison of inbred lines derived by doubled haploidy and single seed descent in spring barley (Hordeum vulgare)
Authors: CALIGARI P. D. S. , POWELL W. , JINKS J. L. 
Published: February 2008

SUMMARYSamples of Fx inbred lines, derived by doubled haploidy (DH) and single seed descent (SSD) from five spring barley crosses were compared for agronomic characters. It was shown that, over this range of diverse crosses, inbreds derived by either technique could surpass the better parent or even the heterotic F1. The means of the DH and SSD were, however, different for a number of characters, as well as differing from the mid‐parent value. It was concluded that these differences stemmed from the presence of interacting genes showing linkage disequilibrium, although there was no unambiguous test to distinguish this from differential survival during the production of inbreds. This view was further supported by the finding that the DH sample, which tends to preserve existing linkages, produced a higher proportion of lines exceeding the better scoring parent when compared with the SSD population.
Observations on the distribution of potato cyst‐nematodes, Globodera rostochiensis and G. pallida on two fenland potato farms
Authors: WHITEHEAD A. G. , WESTERDIJK C. E. 
Published: February 2008

SUMMARYThe distribution of potato cyst‐nematodes, Globodera rostochiensis and G. pallida was surveyed in two widely separated fenland potato farms in Eastern England. Evidence was obtained of the suppression of G. rostochiensis and increase of G. pallida populations when Maris Piper and other potatoes with the same gene (H1) for resistance to G. rostochiensis are grown. Numbers of G. rostochiensis and/or G. pallida in the soil could not be related directly to recent potato cropping histories of the fields. Identification of the two species of Globodera by the presence and colour of females on the roots of Désirée, Maris Piper, Cromwell (A27/20) and A25/11 potatoes were confirmed by agarose gel isoelectric focussing of general proteins. Cromwell exhibited little or no resistance to G. pallida at Woodwalton. A25/11 was more resistant to this species at Woodwalton but was susceptible to G. rostochiensis. The results of these surveys emphasise the need for carefully planned and integrated control programmes based on the use of resistant cultivars of potato, crop rotations and appropriate nematicide use to combat the growing problem of G. pallida, especially in organic soils.
Within‐cultivar differences in relative leaf growth rates at low temperature of onion seedlings are not heritable
Authors: BREWSTER J. L. , BUTLER HEATHER A. 
Published: February 2008

SUMMARYOnion seedlings of two open‐pollinated cultivars were grown either at a constant 10°C or outdoors in spring and were selected for high, medium or low relative leaf growth rate, RL. Flowering plants within each RL group were crossed using controlled pollination for the 10°C selections and as a fly‐pollinated polycross for the outdoor selections. The pollen donors of the 10°C selections were also selfed. Despite the wide variation of RL in the parent populations, there was no indication of heritability of RL. Mean RL was significantly lower for the progeny from self‐rather than cross‐pollinations as was initial leaf area and rate of seedling emergence.
The use of protein A‐sandwich ELISA as a means for quantifying serological relationships between members of the tobamovirus group
Authors: HUGHES J. d‘A. , THOMAS B. J. 
Published: February 2008

SUMMARYIndirect protein A sandwich ELISA (PAS‐ELISA) was used to determine the serological relationship between eight tobamoviruses with antisera to 26 viruses and virus strains within the group. Very distant relationships were determined by trapping virus with heterologous antiserum and detecting it with homologous antiserum, while near and close relationships were differentiated by using heterologous antiserum each time. The results were esssentially consistent with previously recorded relationships determined by tube precipitin and other serological tests.Since PAS‐ELISA requires much less antiserum than many conventional tests and does not require the purification of IgG or virus, it may offer many advantages in the detection of serological relationships.
The effect of augmenting grain aphid (Sitobion avenae) numbers in a field of winter wheat in spring on the aphid's abundance in summer and its relevance to the forecasting of outbreaks
Authors: ENTWISTLE J. C. , DIXON A. F. G. 
Published: February 2008

SummarySitobion avenaewas introduced into areas within a field of winter wheat in Norfolk in mid‐May 1985, when the indigenous population was negligible. Aphid numbers in these areas increased for the first 3 wk and declined for the next 4. A secondS. avenueintroduction into the same areas and into previously uninfested areas was carried out 5 wk after the first introduction, when the crop was at ear emergence complete (G.S. 59). This increased aphid numbers in the previously uninfested areas, but numbers in the previously infested areas continued to decline to below the level in control areas during the subsequent 2 wk. Populations in all areas then increased rapidly to a maximum, followed by a rapid final decline. Monitoring of the aphid and natural enemy populations, and caging aphids onto the crop, revealed that the principal cause of the population decline around G.S. 59 was predation by syrphids. The relevance of these findings to the problem of forecastingS. avenaeoutbreaks is discussed, and a general explanation for cereal aphid outbreaks is put forward.
Distribution and infectivity of yellowing viruses in field‐grown sugar‐beet plants
Authors: SMITH HELEN G. 
Published: February 2008

SummaryBeet yellows virus (BYV) and beet mild yellowing virus (BMYV) are introduced to sugar‐beet root crops in spring by winged aphids, and are spread within the crops from these foci of infection. The rate of spread is likely to be influenced by the speed with which the initially inoculated plants become sources of infection. Studies reported in this paper showed that when field‐grown sugar beet were inoculated at the 2–4 leaf stage with BYV, the virus was detected in the youngest leaves after 1 wk, in all leaves after 2 wk and was readily acquired and transmitted by Myzus persicae from these infected leaves. In contrast BMYV multiplied and spread more slowly in plants inoculated at the 2–4 leaf stage, and was not acquired and transmitted by M. persicae very efficiently early in the season. When plants were inoculated at the 15–20 leaf stage there was less difference between the two viruses. The consequences of the observations in relation to aphid control are discussed.
Glucosinolates in oilseed rape (Brassica napus) and the incidence of pollen beetles (Meligethes aeneus)
Authors: MILFORD G. F. J. , PORTER A. J. R. , FIELDSEND JANE K. , MILLER CLAIRE A. , LEACH J. E. , WILLIAMS INGRID H. 
Published: February 2008

SummaryDuring an early stage of migration into a field of oilseed rape in the spring of 1988, more pollen beetles were observed on the double‐low variety, Ariana, than on the adjacent single‐low varieties, Bienvenu and Mikado. More beetles were found on open flowers on terminal racemes than on yellow and green flower buds on lateral racemes.Five alkenyl, three indolyl and two aromatic glucosinolates were identified in the floral tissues of oilseed rape. The major compounds were progoitrin (2‐OH, 3‐butenyl) and glucobrassicanapin (4‐pentenyl). There were no differences in the types and concentrations of glucosinolates present in the terminal and lateral racemes of any variety, and only small differences between single‐ and double‐low varieties. Concentrations of glucosinolates in floral tissues of crops grown with a little nitrogen were twice those of well‐fertilised crops. There was no association between the number and distribution of pollen beetles on plants and the amounts or types of glucosinolates present in floral tissues.
Inheritance pattern of downy mildew resistance in advanced generations of sorghum*
Authors: REDDY BELUM V. S. , MUGHOGHO L. K. , NARAYANA Y. D. , NICODEMUS K. D. , STENHOUSE J. W. 
Published: February 2008

SummaryIn a project aimed to incorporate downy mildew resistance into sorghum hybrid seed parents, we screened F4 and F5 families for resistance to the ICRISAT Centre isolate of the pathogen using a greenhouse seedling screening technique. The families originated from a cross of 296B (susceptible) and IS 18757 [(QL‐3) resistant]. The F4s were obtained from agronomic selection in F2s and F3s, and the F5 families from advancing plants identified as resistant in segregating F4 families.The resistant plants were more than double the number of susceptible plants in the F4 and almost so in the F5 suggesting that resistance to downy mildew was dominant. Of the four genetic models examined (a single‐locus model and three two‐locus models with complementary, inhibitory, and a combination of complementary and inhibitory interactions), the two‐locus model with independent segregation and a combination of complementary and inhibitory inter‐allelic interaction appeared to be most appropriate in explaining the segregation patterns within and among F4 and F5 families. Accordingly, for resistance to P. sorghi, the suggested genotypes for IS 18757 is PlaPlaPlbPlb and for 296B is PlaPlaPlbPlb.
A simulation model of Avena fatua L. (wild‐oat) growth and development
Authors: WEAVER S. E. , KROPFF M. J. , COUSENS R. 
Published: February 2008

SummaryAn eco‐physiological simulation model of the growth and development of Avena fatua was parameterised and tested. The model simulates growth ofA. fatua, in kg dry matter ha‐1 day‐1 from sowing to maturity as a function of irradiance, temperature and various species characteristics. Parameter values were derived from the literature and from field experiments, including both autumn and spring sowings of A. fatua over three years at two sites in southern England. With two exceptions, a single set of parameter values was sufficient to accurately simulate the emergence, growth and development of both autumn and spring cohorts over all years and sites. The two exceptions were the result of differences between autumn and spring cohorts of A. fatua in the rate of early leaf area growth and in the relationship between specific leaf area and developmental stage.
Dissemination and detection of peanut clump virus in groundnut seed
Authors: KONATE G. , BARRO N. 
Published: February 2008

SUMMARYExperiments were done to assess the role of seed‐transmission in the dissemination of peanut clump virus (PCV) in groundnut (Arachis hypogea L.), and the usefulness of enzyme‐linked immunosorbent assay (ELISA) for detecting the virus in infected groundnut seed. The virus was present in 7.5% of seedling progeny from infected plants and could be detected in 16.5% of the seeds by ELISA. When groundnut seeds were grown in a field contaminated by the virus, it was shown that by roguing the infected plants, only 0.1% of the seeds from the remaining plants contained the virus. It was also established that the level of contamination of seeds by the virus was inversely proportional to the seed size.
A rapid serological test for detecting Fusarium oxysporum f.sp. narcissi in Narcissus
Authors: LINFIELD CHRISTINE A. 
Published: February 2008

SUMMARYPolyclonal antiserum was elicited against a strain of Fusarium oxysporum f.sp. narcissi (GCRI80/26) and a specific and sensitive enzyme‐linked immunosorbent assay developed. Antiserum raised to cell wall fractions gave better recognition than that to cytoplasmic fractions. Recognition was equally good in artificially and naturally infected bulbs. Little cross‐reactivity in bulb tissue was shown by three other bulb‐rotting fungi. Nine isolates of F. oxysporum f.sp. narcissi from a wide geographic area gave similar results in an indirect ELISA of mycelial extracts, although some cross‐reactivity was observed with two other Fusarium spp. Four Fusarium spp. and four other fungi showed little cross‐reactivity. Ten days after inoculation the pathogen was readily detected in the base plate area of three Narcissus cultivars and points remote from the inoculation site in the most susceptible cultivar. A direct correlation was observed between positive results in the enzyme‐linked immunosorbent assay and recovery of the pathogen on selective medium.