bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of three rates of aldicarb and of different degrees of resistance and tolerance in potato cultivars on yield and post‐harvest population densities of the potato cyst nematodes Globodera rostochiensis and G. pallida
Authors: TRUDGILL D. L. , MATHIAS P. L. , TONES S. J. 
Published: February 2008

SUMMARYThree field experiments were made to determine the effectiveness of small‐plot trials in detecting differences between potato cultivars/clones in their tolerance of damage by potato cyst‐nematodes. A nematicide (aldicarb) was applied at three rates to decrease nematode damage. The largest rate of aldicarb increased tuber yields most but the relationship between yield response and nematicide rate was not linear. The yield increases of the cultivars and clones differed, indicating that they have different degrees of tolerance of potato cyst nematodes. The results were analysed in several ways and the untreated yield as a proportion of the treated provided the best means of expressing and comparing tolerance; but whichever method was used the tolerance rankings of the cultivars and clones were similar.At two sites infested with Globodera rostochiensis, the rankings of the 10 cultivars and clones were similar but at a third site, heavily infested with G. pallida, they were different. Aldicarb decreased the nematode population density after harvest at the G. pallida site but was less effective at the G. rostochiensis sites, which were less heavily infested. Growing resistant or partially resistant potatoes usually prevented nematode increase, and the more resistant cultivars and clones decreased population densities markedly.
Seed survival and seasonal emergence in some species of Geranium, Ranunculus and Rumex
Authors: ROBERTS H. A. , BODDRELL JUNE E. 
Published: February 2008

SUMMARYSeeds of 14 species were collected, usually in each of 2 or 3 yr, and mixed with the top 7.5 cm of sterilised soil confined in cylinders sunk in the ground outdoors and cultivated three times yearly. Seedling emergence was recorded for at least 3 and usually 5 yr. Most seedlings of Ranunculus bulbosus and Rumex acetosa appeared during the autumn of sowing, while the main emergence of Geranium pratense. Ranunculus acris, Rumex conglomeratus and R. maritimus was in the following spring. Emergence of G. pyrenaicum and G. robertianum took place throughout much of the year after sowing. Seeds of all these species were relatively short‐lived in cultivated soil, and few seedlings appeared after the second year.Seed survival was greater in G. dissectum. G. molle, Rumex acetosella. Ranunculus sceleratus and especially R. repens, of which emergence in the fifth year after sowing amounted to 4% of the seeds sown. Emergence from the persistent seed bank was mainly from May to September for G. dissectum and G. molle and during autumn for Ranunculus flammula and R. sceleratus, while seedlings of Ranunculus repens and Rumex acetosella appeared sporadically over most of the year.
A simple model relating yield loss to weed density
Authors: COUSENS ROGER 
Published: February 2008

SUMMARYA simple model is developed to describe crop yield loss as a function of weed density. The model, a rectangular hyperbola, has two agronomically meaningful parameters which together can be used as indices of competitiveness. Examples are given where the model is fitted to experiments from the literature. Seventeen other models are compared through application to 22 data sets. It was found that for the data available two‐parameter yield loss models were generally sufficient.The hyperbolic model gave the best description of data, but this was only marginally better than three other models. This conclusion is discussed with reference to the popular sigmoidal model.
The effect of cultivation system and soil factors on the performance of herbicides against Alopecurus myosuroides
Authors: MOSS S. R. 
Published: February 2008

SUMMARYAspects of chemical and cultural control of Alopecurus myosuroides (blackgrass) in winter wheat were studied on a naturally‐occurring infestation over a 3‐yr period. In two experiments a comparison was made between ploughing and direct drilling, whilst in the third experiment direct drilling alone was used. Straw was spread and burnt in each year. Herbicide treatments were: chlortoluron and isoproturon in all three experiments; diclofop‐methyl and pendimethalin in two experiments; metoxuron, terbutryne, tri‐allate, carbetamide, propyzamide, chlorsulfuron + methabenthiazuron and trifluralin + linuron in one experiment. Herbicides were applied either pre‐emergence, early post‐emergence or late postemergence to separate sub‐plots. Surface soil (0–2.5 cm) samples were collected each year from unsprayed areas and used for soil analyses and for herbicide activity studies in pot experiments.Ploughing resulted in much lower populations of A. myosuroides than direct drilling. Most herbicides gave much better control of A. myosuroides in ploughed than in direct drilled soil in field and pot experiments, regardless of application time. Diclofop‐methyl, applied early post‐emergence at 1.13 kg a.i./ha, was the only herbicide treatment in field experiments to achieve over 90% weed control in direct drilled soil. Differences in adsorption between soils given different cultivations, determined as Kd values for chlortoluron and isoproturon, were much greater than differences in organic matter.The much greater adsorptive capacity of direct drilled soil, and consequently the poorer performance of all soil‐acting herbicides, was attributed to the concentration of burnt straw residues near the soil surface.
Potential for biological control of tent building species of ants associated with Phytophthora palmivora pod rot of cocoa in Papua New Guinea
Authors: MCGREGOR A. J. , MOXON J. E. 
Published: February 2008

SUMMARYThe tents of different ant species collected from young cocoa trees in their first or second year of bearing and free from visible pod rot, were tested for the presence of Phytopthtora palmivora by inoculating wounded cocoa pods with tent material.Tents of all species harboured viable P. palmivora but those consisting mainly of soil were more frequently positive than plant debris‐type tents. Although Anoplolepis longipes, a dominant, ground nesting, non‐tent building species sometimes transported inocula in the laboratory, it did not significantly increase black pod infection in the field. Trees infested with the dominant debris tent building species, Technomyrmex albipes, however, had significantly more black pod than those infested with A. longipes or trees without ants. A. longipes forms dense populations and can exclude other dominant ants and some cocoa pests; its introduction may be a potentially economical method of reducing the transmission of P. palmivora in redeveloped cocoa in Papua New Guinea.
The relation between some growth parameters and yield components of rice as influenced by nitrogen level and genotype
Authors: RAHMAN M. S. 
Published: February 2008

SUMMARYThe effects of three levels of nitrogen (0, 2 and 4 g (NH4)2SO4 per pot) were evaluated in four rice varieties, differing in grain size, under flooded conditions in a tropical environment.Addition of nitrogen increased plant height and leaf number on the main culm, and hastened flowering significantly in all varieties. It also increased the dry weights of leaf, and culm plus sheath at the maximum tillering stage, anthesis and harvest. The average dry weights of both leaf, and culm plus sheath increased significantly in all varieties until anthesis. Following anthesis, the dry weights of both leaf, and culm plus sheath of the large‐seeded varieties, Zhu Lian and PP6R, further increased mainly due to emergence of the late tillers, but decreased in the small‐seeded varieties, IR 747 and P3C26. During grain‐filling, vars Zhu Lian and PP6R accumulated dry matter more than the other two varieties and did not use their reserve starch present in the culm plus sheath, presumably because of the lack of demand. By contrast, current photosynthesis and ‘reserve’ contributed about 70% and 30%, respectively, of the grain yield in IR 747 and P3C26.Addition of nitrogen increased grain yield significantly in all varieties. The yield increase in IR 747 and PP6R was essentially due to increase in grain number, but that in P3C26 and Zhu Lian was due to increases in both grain size and grain number, the latter having much greater influence. Neither the percentage of filled spikelets nor the 1000‐grain weight was influenced by nitrogen addition. It was concluded that grain number is the single most important yield component in rice. Path‐coefficient analysis indicated that in a breeding programme involving these four rice varieties, the cross between Zhu Lian and P3C26 would be most successful in an effort to combine high spikelet number and large grain size.
Increase in esterase activity during maturation of Malus pumila fruit
Authors: GOODENOUGH P. W. , RILEY T. E. W. 
Published: February 2008

SUMMARYIn a range of dessert cultivars of Malus pumila, the esterase in the fruit showed a rise in activity during the period of fresh weight gain. This was the case when activity was expressed on a protein or a fresh weight basis. Both fruit which matured at 100 days after anthesis, and fruit which matured later, showed a similar rate of increase. However, a cultivar used for processing rather than eating showed a much reduced rate of esterase increase.
The effects of nitrogen and sulphur nutrition on the response of Brussels sprout plants to infestation by the aphid Brevicoryne brassicae
Authors: KORITSAS V. M. , GARSED S. G. 
Published: February 2008

SUMMARYThe effects of two levels each of nitrogen and sulphur nutrition and of infestation by Brevicoryne brassicae on the growth of Brussels sprout plants were studied in factorial experiments.All the plants receiving high nitrogen treatments grew more rapidly than those with low, but in infested plants the improvement in growth at the higher levels of nitrogen was offset by the increased size of aphid populations. Low sulphur nutrition increased the growth of plants receiving high nitrogen and of the aphids feeding on them. Leaf diffusive resistances and chlorophyll concentrations were greater with high nitrogen, but were significantly lowered by infestation in all nutrient treatments. Infestation decreased leaf total nitrogen concentration at the sites of feeding, but effects on soluble nitrogen were not significant. Removal of aphids 72 days after initial infestation did not cause marked plant recovery during the next 22 days.It is concluded that the benefits of increased yield resulting from high nitrogen levels must be balanced against the greater potential for damage by aphids.
The distribution and abundance of predatory Coleoptera overwintering in field boundaries
Authors: SOTHERTON N. W. 
Published: February 2008

SUMMARYSoil samples were taken over the period December ‐ February in 1981‐82 and in 1982‐83 from four types of field boundaries on farmland in Hampshire to estimate the distribution and abundance of overwintering polyphagous predatory Coleoptera. Supplementary data were obtained from surface searches in four types of field boundaries on farmland in Essex. Different species of predators occurred in significantly higher numbers in specific types of field boundaries but in Hampshire, hedge banks and shelterbelts were more attractive as overwintering sites than grass banks or grass strips for most species and in Essex a combined grass bank, ditch and hedge boundary was more suitable than other boundary types for three of the four species studied.
Effect of undersowing potatoes with grass on potato aphid numbers
Authors: McKINLAY R. G. 
Published: February 2008

SUMMARYThe numbers of the potato aphids, Macrosiphum euphorbiae and Myzus persicae, were counted on potatoes undersown and not undersown with perennial ryegrass in field experiments during 1980 and 1981. The numbers of aphids on potatoes undersown with grass were found generally to be smaller than the aphid numbers on potatoes not undersown with grass. Tuber yields were not significantly reduced by the undersowing of potatoes. The agronomic feasibility of undersowing potatoes for aphid control is discussed.
Infection of red raspberry styles and carpels by Botrytis cinerea and its possible role in post‐harvest grey mould
Authors: McNICOL R. J. , WILLIAMSON B. , DOLAN ALISON 
Published: February 2008

SUMMARYThe gynecium was selected for histological studies of infection of red raspberry (Rubus idaeus) flowers in the laboratory because it is one of several possible infection sites leading to fruit grey mould. Infection of emasculated flowers occurred when dry conidia were dusted on to receptive stigmas. The conidia germinated in the stigmatic fluid of both non‐pollinated flowers and flowers pollinated before inoculation, their germ tubes then penetrated the stigma and hyphae grew intercellularly through the transmitting tissues of the style to enter the carpel within 7 days. The possible roles of stylar infections and endophytic mycelium are discussed in the context of grey mould development.
The effect of magnesium ions on the solubility of polyhedral inclusion bodies and its possible role in the inactivation of the nuclear polyhedrosis virus of Spodoptera littoralis by the cotton leaf gland exudate
Authors: ELLEMAN C. J. , ENTWISTLE P. F. 
Published: February 2008

SUMMARYPolyhedral inclusion bodies of Spodoptera littoralis nuclear polyhedrosis virus (NPV) treated with solutions of cotton leaf gland exudate (a process which has been shown to inactivate the NPV), exhibited a marked decrease in solubility in dilute alkali. This process is reversible with EDTA and can be simulated by MgCI2. The effect of magnesium ions on solubility did not involve the enzyme, alkaline protease. It is suggested that this decrease in solubility may be involved in the mechanism by which the cotton leaf inactivates the NPV. However, since MgCI2 alone could not be shown to inactivate NPV in vitro it must be assumed that other constituents of the leaf gland exudate also play a part.
Biological and biochemical properties of an isolate of cherry rasp leaf virus from red raspberry
Authors: JONES A. T. , MAYO M. A. , HENDERSON SUSAN J. 
Published: February 2008

SUMMARYA mechanically transmissible virus obtained from symptomless plants of a red raspberry selection imported into Scotland from Quebec, Canada was indistinguishable serologically from a cherry isolate of cherry rasp leaf virus (CRLV). The raspberry isolate, CRLV‐R, was graft transmitted to several virus indicator species and cultivars of Rubus without inducing noticeable symptoms. In Chenopodium quinoa sap, CRLV‐R lost infectivity after dilution to 10‐5 or heating for 10 min at 60°C but was infective after 16 days (the longest period tested) at 18°, 4° or ‐ 15°C. The virus particles are isometric, c. 28 nm in diameter, and were purified with difficulty from infected C. murale and C. quinoa plants. The particles comprise two nucleoprotein components with sedimentation coefficients of 89 and 115 S and are prone to aggregate during purification. When centrifuged to equilibrium in CS2SO4 solution, purified virus preparations formed two major components with p= 1·28 and 1·36 g/cm3. Virus particles contained two RNA species which, when denatured in glyoxal and electrophoresed in agarose gels, had estimated mol. wt of 2·56 × 106 (RNA‐1) and 1·26 × 106 (RNA–2). Infectivity of CRLV‐R RNA was abolished by treatment with proteinase K, suggesting that the RNA is linked to protein necessary for infectivity; RNA molecules contained polyadenylate. In reticulocyte lysates, CRLV‐R RNA stimulated the incorporation of 3H‐leucine, mainly into two polypeptides of estimated mol. wt 200 000 and 102 000. When electrophoresed in polyacrylamide gels, protein obtained from CRLV‐R particles purified by centrifugation to equilibrium in Cs2SO4 separated into three bands with estimated mol. wt 26 000, 23 000 and 21 000.
An analysis of leaf growth in sugar beet.
Authors: MILFORD G. F. J. , POCOCK T. O. , RILEY JANET 
Published: February 2008

SUMMARYThe influence of season, and certain agronomic treatments (irrigation, nitrogen fertiliser, density of planting and sowing date) on leaf number were analysed in a series of sugar‐beet crops grown during the five seasons 1978‐82. Leaf appearance was a linear function of thermal time (accumulated temperature above 1°C) and could be described by four variables: a) the thermal duration of the seedling establishment phase, d′s; b) the thermal time interval between appearance of each of the early leaves, θe; c) the thermal duration of the early phase of leaf appearance, d'a, and d) the thermal time interval between the appearance of each of the later leaves, θ1. The progression of leaf death could also be described by a thermal time interval, θd.There were only small differences in the number of leaves produced by the eleven crops grown during the five seasons. Such differences as appeared, were largely attributable to changes in d'a and θ1, which were interpreted as responses to increasing competition for mineral nutrients and assimilate at the shoot apex. θe was similar in all crops; 30°Cdays were needed between the appearance of each of the early leaves. Only the early leaves died. Each one was retained by the plant longer than its predecessor. Increasing soil moisture deficit under an unirrigated crop shortened θd and depriving crops of nitrogen lengthened it. It is concluded that small differences in the rates of leaf appearance did not greatly influence the rates at which leaf canopies expanded early in the season, but that the rates of leaf death influenced both the time at which the canopies reached their maximum sizes and the rates at which leaf areas subsequently declined.
An analysis of leaf growth in sugar beet.
Authors: MILFORD G. F. J. , POCOCK T. O. , RILEY JANET , MESSEM A. B. 
Published: February 2008

SUMMARYThe expansion and persistence of leaves of sugar beet (Beta vulgaris) were measured in a series of crops grown in five seasons between 1978‐82 to establish how their growth varied between seasons, was affected by certain agronomic treatments and contributed to changes in leaf area index. Thermal time (accumulated temperature above 3°C) rather than days from sowing was used as a basis for comparing growth in different seasons.Leaf size depended on position on the stem and was influenced by sowing date, nitrogen fertiliser rate, plant population and the development of crop water stress. Changes in size were mostly associated with changes in the rates, rather than the duration, of expansion. When compared across seasons, the rate and duration of expansion of individual leaves were strongly negatively correlated so leaf size tended to be a more stable characteristic than either of its determining components. Nevertheless, final leaf areas varied by as much as 20% between seasons and this variation was attributable more to the temperatures experienced by leaves prior to unfolding and to the amounts of nitrogen present in the shoot at that time than to conditions during the main period of leaf expansion.
Preliminary laboratory tests with two species of entomophilic nematodes for control of Musca domestica in intensive animal units‡
Authors: RENN N. , BARSONf G. , RICHARDSON P. N. 
Published: February 2008

SUMMARYTwo species of entomophilic nematodes, Heterorhabditis heliothidis (NZ strain) and Steinernema feltiae (Agriotos strain) were tested in the laboratory against immature and adult stages of a strain (G) of Musca domestica with multiple insecticide‐resistance. Both species of nematodes killed larval stages of M. domestica on inoculated filter papers. S. feltiae was the most virulent parasite, and killed >90% of all larval stages at the two highest doses of 25 000 and 50 000 nematodes per 0·5 ml tap water. No puparia were parasitised by either species. There was no parasitism of the larval stages after exposure to chicken manure treated with nematodes. All adult flies were parasitised after they were exposed to bait‐pads previously inoculated with S. feltiae, 93.3% were parasitised by H. heliothidis.
Apple mosaic virus isolated from hop plants in Japan
Authors: SANO T. , SASAKI M. , SHIKATA E. 
Published: February 2008

SUMMARYA strain of apple mosaic virus was isolated from hop plants in Japan. The virus was purified from young hop plants and back‐inoculated to virus‐free hop plants obtained by meristem tip culture. Inoculated plants developed chlorotic spots, ringspots and a band pattern accompanied by necrosis in the inoculated and systemically infected leaves. Shoot tips of infected plants sometimes became necrotic and these symptoms resembled those of a ring‐ and band‐pattern mosaiclike disease prevalent in hop gardens in Japan. Since apple mosaic virus was recovered from infected plants, it is likely that the virus was the causal agent of this disease.Agar gel double diffusion tests and ELISA showed the hop virus to be serologically closely related to apple mosaic virus (ApMV), and distantly related to prunus necrotic ringspot virus (PNRSV).The virus had a narrow host range, and infected only cucumber of 18 species of Cucurbitaceae, Chenopodiaceae, Leguminosae or Solanaceae inoculated. It produced chlorotic spots on the inoculated cotyledons of cucumber, but no systemic infection. By contrast, ApMV from apple and PNRSV from peach had wide host ranges and infected cucumber plants systemically.
The influence of cultivar and isolate on the susceptibility of red raspberry canes to Didymella applanata
Authors: PEPIN H. S. , WILLIAMSON B. , TOPHAM PAULINE B. 
Published: February 2008

SUMMARYThe internodes of young canes of a single red raspberry selection were inoculated in the field with 32 isolates of Didymella applanata from diverse localities throughout the British Isles. All isolates were pathogenic but differed in virulence estimated by lesion length; their origin and virulence were not related.Four petioles on young canes of seven cultivars were inoculated in the glasshouse with 13 of the isolates. The axillary buds at treated nodes were shorter and the emergence of lateral shoots was substantially less than at non‐inoculated nodes in all seven cultivars. Although there were significant cultivar × isolate interactions, these were small in comparison to the effects of inoculation, cultivar and position of the treated node.The cultivar × isolate interactions between eight cultivars and 14 isolates were also studied in the field by inoculation of petioles and the internodes of young canes. Joint regression analysis of bud and lesion lengths revealed significant cultivar × isolate interactions but no discontinuous variation in the expression of disease was found. A principal components analysis using % nodes infected, % reduction in bud length and % lateral shoot failure confirmed the relationship between these variates and gave three vectors. The first (83.3% of variation) named the ‘resistance’ vector described the relative resistance or susceptibility of cultivars, the second ‘tolerance’ vector (13.4%) described the variation due to relative tolerance or intolerance of these genotypes and the third a ‘bud response’ vector accounted for only 3.3% of the variation.
Relationships between seed weight and endosperm characteristics in carrot
Authors: GRAY D. , WARD J. A. 
Published: February 2008

SUMMARYCarrot seed weight, over the range 0·37 to 3·77 mg, and endosperm volume were closely and linearly related to endosperm cell number, the relationships accounting for 77–85% and 84–94% of the variance in seed weight and endosperm volume, respectively. The relationships were similar for seeds of cvs Chantenay and Amsterdam, and for seeds from primary and secondary umbels but were affected by season of seed production through differences in cell volume.