bluuebunny/crossref_metadata_2025_split huggingface dataset:
Further studies on the occurrence and inheritance of resistance in red raspberry to a resistance‐breaking strain of raspberry bushy dwarf virus
Authors: JENNINGS D. L. , JONES A. T. 
Published: February 2008

SummaryA strain of raspberry bushy dwarf virus (RBDV‐RB), discovered in England in 1981, readily infects by grafting many raspberry cvs that have gene Bu, which confers strong resistance or immunity to isolates of the common strain. Haida is one of two cultivars that are highly resistant or immune from RBDV‐RB, but both its parents, cvs Creston and Malling Promise, are infectible. Studies of the segregation of resistance to both RBDV‐RB and a common strain of RBDV (D200) in four progenies related to cv. Haida or its two parents, showed that resistance to RBDV‐RB was heritable and occurred when gene Bu was present with a second resistance component whose inheritance is probably multigenic. There was some indication that the second component might be a form of partial resistance to graft inoculation of varying expression, and that cv. Haida possesses this resistance at a high level that has not been distinguished from immunity in the graft inoculations used. Cultivars Creston and Malling Promise possibly have this resistance to a lesser degree, while resistance in cv. Heritage has been distinguished from immunity only by extensive graft tests. Some possible implications for breeding RBDV‐RB resistant cultivars are discussed.
Histochemical localisation of carboxylesterases in roots of Lycopersicon esculentum in response to Meloidogyne incognita infection
Authors: MELILLO M. T. , BLEVE‐ZACHEO T. , ZACHEO G. , GAHAN P. B. 
Published: February 2008

SummaryA cytochemical study of esterase activity of tomato cultivars resistant (VFN8) and susceptible (Roma) to the root‐knot nematode Meloidogyne incognita has shown activity present in root tissue of both cultivars.Inhibitor studies indicated the likely involvement of carboxy‐ and acetyl‐esterases as components in the prostele and cortical cells of cv. Roma 1, 2, and 3 days after nematode infestation. In contrast, necrotic cells immediately adjacent to the nematode in roots of VFN8 were seen to contain high levels of phenolics by 3 days after infection with the adjacent cells having high levels of carboxylesterase activity. The possible role of the enzyme in the hypersensitive response of tomato plants during nematode infection is discussed.
Effects of triazole growth retardants on oilseed rape; photosynthesis of single leaves
Authors: BUTLER D. R. , PEARS E. , CHILD R. D. , BRAIN P. 
Published: February 2008

SummaryRates of CO2 exchange were measured for single leaves on oilseed rape plants after application of triapenthenol and BAS111. For leaves which expanded after treatment, there was no detectable change in the rate of photosynthesis per unit leaf area compared with the control for either chemical about 3 wk after application. For fully expanded leaves at the time of application a reduction in the rate of photosynthesis per unit leaf area occurred and was sustained for at least 2 wk. The reduction in the rate of photosynthesis is explained by decreased stomatal conductance.
The effects of different external nitrate concentrations on growth of Avena sativa cv. Amuri treated with diclofop‐methyl
Authors: ANDREWS M. , DICKSON R. L. , FOREMAN M. H. , DASTGHEIB F. , FIELD R. J. 
Published: February 2008

SummaryAvena sativa cv. Amuri fed either low or high nitrate was sprayed with diclofop‐methyl (1 kg a.i. ha‐1) at the three leaf stage. The short term effects of the herbicide on chlorophyll concentration of leaves (laminae) and short and long term effects on d.wt of the component plant parts were determined by comparison with unsprayed plants.For unsprayed and sprayed plants, total leaf d.wt approximately doubled during the first twelve days after commencing treatments. Growth was substantially greater at high nitrate than low nitrate. For unsprayed plants, the increase in total leaf d.wt was due primarily to growth of leaf 3 but for sprayed plants it was due to growth of leaves 1 and 2. Twelve days after commencing treatments, d.wt of leaves 1 and 2 was substantially greater for sprayed plants than for unsprayed plants given similar nitrate, while chlorophyll concentration was substantially less. Leaf 3 d.wt and chlorophyll concentration were substantially greater in unsprayed plants than in sprayed plants given similar nitrate. For unsprayed plants, values were greater at high nitrate than low nitrate, for sprayed plants the converse was the case.Forty nine days after commencing treatments, unsprayed plants had a greater total plant d.wt than sprayed plants given similar nitrate. Total plant d.wt for unsprayed plants was greater at high nitrate than low nitrate, the opposite was the case for sprayed plants. Unsprayed plants at both nitrate levels and sprayed plants given low nitrate produced seed heads but sprayed plants given high nitrate did not. Diclofop‐methyl at a rate of 0.3 kg a.i. ha‐' stopped seed head production at high nitrate. Retention and uptake of diclofop‐methyl were not significantly different at low and high nitrate. At 1 kg a.i. ha‐l diclofop‐methyl, plants switched from low to high nitrate at spraying showed damage similar to that shown by plants given high nitrate throughout. Addition of 200 μg GA into the leaf sheaths two days prior to spraying increased the efficacy of diclofop‐methyl at low nitrate.It is proposed that increased efficiency of diclofop‐methyl at high nitrate is due to increased leaf damage caused by a greater rate of leaf expansion.
The response of determinate and semi‐determinate faba bean varieties to different sowing dates in the spring
Authors: PILBEAM C. J. , HEBBLETHWAITE P. D. , RICKETTS HELEN E. 
Published: February 2008

SummaryField trials conducted during 1986 and 1987 at the University of Nottingham compared the growth and development of two varieties of faba bean, Alfred and Ticol, in response to three different dates of sowing in the spring.Grain yields were greater the earlier the crop was sown. This difference was attributed to the larger canopy size, especially at the pod‐filling stage of the earlier sown crops. This probably reflected the influence of temperature on the expansion and senescence of leaves during development.A semi‐determinate variety of faba bean, Alfred, yielded 31% more than a determinate variety, Ticol. This difference was not attributable to any particular yield component. In 1986, it was correlated with pods per podding node and in 1987 with the number of seeds per pod. Three reasons can be advanced to explain this greater yield. Firstly, Ticol branched more than Alfred and so a greater proportion of its total reproductive nodes were borne on the branches rather than the mainstem. Branches were shown to be inferior in terms of yield production. Secondly, it was demonstrated that Ticol was probably less able to transfer stored assimilates from the stem to the developing pod than Alfred. Thirdly, Alfred had a larger canopy during pod development than Ticol.
Effects of ethylene on the susceptibility to Botrytis cinerea infection of different tomato genotypes
Authors: BARKAI‐GOLAN RIVKA , LAVY‐MEIR GILA , KOPELIOVITCH E. 
Published: February 2008

SummaryEthylene at 10 and 100 μl/litre stimulated germ‐tube elongation of Botrytis cinerea spores incubated within normal and non‐ripening nor tomato fruits, but had little influence on the total percent of germination. Values of germ‐tube length within the mature‐green normal fruits and the mature‐green or mature nor fruits were similar to those recorded within the normal mature fruits when held in air. Exposure of the normal and the mutant fruits to 100 μl/litre ethylene immediately after inoculation with B. cinerea insignificantly increased lesion development, but resulted in increased sporulation. When tomato fruits were exposed to ethylene for 3 days before inoculation a marked stimulatory effect on rot development was exhibited on the mature‐green normal fruits but not on the nor mutant fruits. The results indicate that exogenous ethylene may directly stimulate germ tube growth of B. cinerea in both normal and mutant fruit, but that it may affect subsequent fungal growth indirectly, via stimulation of the ripening process, only in preclimacteric normal tomato fruit.
Colonisation of maize by aphid vectors of barley yellow dwarf virus*
Authors: COCEANO P. G. , PERESSINI S. 
Published: February 2008

SummaryWith the present research we tried to evaluate the contribution by maize (corn) to the spread of aphid vectors and in the maintenance of barley yellow dwarf virus (BYDV) in Friuli ‐ Venezia Giulia (North East Italy). We also wanted to examine differences between two corn genotypes in relation to aphid colonisation. Some aspects of plant colonisation and the frequency of BYDV infected colonies in the two cultivars are discussed.
The effect of satellite RNA on cross‐protection among cucumber mosaic virus strains*
Authors: WU GUSUI , KANG LIANGYI , TIEN PO 
Published: February 2008

SummaryTobacco and pepper plants were inoculated with a mild strain of cucumber mosaic virus (CMV) with or without satellite RNA, then challenged by a virulent CMV strain devoid of satellite RNA and protection effects detected by assessment of symptoms and protein A sandwich ELISA for the challenge CMV strain. Protection was obtained both in the presence and the absence of satellite RNA in the preinoculating strain but was greater when it was present.
Selection of nematodes for zero cyst phenotypes with soybean
Authors: LUEDDERS VIRGIL D. 
Published: February 2008

SummaryDefinitive genetic studies of the soybean cyst nematode (Heterodera glycines)‐soybean (Glycine max) relationship are complicated by the use of soybean lines with many genes for resistance to heterogeneous, amphimictic nematode populations. Inbreeding and artificial selection of cyst nematodes decreased their ability to form cysts on specific soybean lines assumed to have few genes for resistance. In the initial sib selection, single cysts were used to inoculate two‐seedling units consisting of a seedling of one soybean line to evaluate the nematodes' ability to form cysts on it and a seedling of another line for comparison and maintenance of the nematode inbreds being developed. This method permitted some selection but was slow and labour‐intensive. A better method of artificial selection for fewer cysts on specific soybean lines was to inbreed nematodes for about four generations, then to evaluate the inbreds for ability to form cysts on the soybean lines before selecting particular inbreds with poor ability to form cysts for the development of more inbreds. This increased the frequencies of specific nematode genes for avirulence or alleles for incompatibility with soybean lines containing the interacting [gene‐for‐gene] alleles for incompatibility (genes for resistance). The artificial selection apparently was for at least two nematode alleles for incompatibility since at least two soybean alleles were indicated in the segregation from crosses of soybean lines.
A testing sequence for reducing rejection of potential biological control agents for weeds
Authors: WAPSHERE A. J. 
Published: February 2008

SummaryMany insect agents, selected for the biological control of weeds and tested under restricted cage conditions, have been rejected as unsafe for introduction because of an apparent increase in host range compared with that observed under natural conditions. These aberrant results appear to be due to the insects' inability to follow the normal behavioural sequence based on appropriate cues which lead to correct host selection. It is suggested here that a reverse sequence of testing which progressively reduces the degree of restriction and deletes unattacked plants at each stage, until only a few remain to be tested under conditions as near natural as possible, would allow previously rejected insects to be used as biological control agents.
Effects of the plant growth regulator chlormequat on plant form and yield of triticale
Authors: NAYLOR ROBERT E.L. 
Published: February 2008

SummaryThree field experiments were conducted in order to evaluate the effect of application of the plant growth regulator chlormequat on growth and yield of the cereal triticale. Application of chlormequat resulted in shorter triticale plants as a result of restricted elongation of the upper internodes of the stem. These shorter plants produced a lower weight of straw and were more resistant to lodging. In two experiments chlormequat application led to no statistically significant increase in triticale grain yield; in a third yield was increased. Chlormequat consistently increased the number of grains per ear but this was offset to some extent by a lower mean grain weight. Yield was closely correlated with the number of grains per m2. Leaf senescence was delayed by chlormequat. The results are consistent with the hypothesis that chlormequat can increase yield potential.
Effects of acidic fog on productivity of celery and lettuce and impact on incidence and severity of diseases
Authors: MUSSELMAN ROBERT C. , McCOOL PATRICK M. 
Published: February 2008

SummaryThe effects of acidic fog on productivity of celery and lettuce were examined using a portable fogging apparatus to expose field plots to simulated fog episodes. Acidic solutions were formulated to simulate fog reported for southern California. Celery (Apium graveolens var. dulec cv. Bishop) and lettuce (Lactuca sativa cv. Mesa 659) were exposed in separate experiments once or twice each week during crop growth and maturation to 1 ‐ to 2‐h of fog at specific acidity levels between pH 1.6 and 3.8. Necrosis occurred as small, irregularly shaped white (celery) or brown (lettuce) lesions on the most exposed portions of the plants. Fog necrosis sufficient to reduce marketability of celery was evident after single exposures at pH 2.4. Although injury occurred on wrapper leaves of lettuce at acidity levels as high as pH 3.4, marketability was reduced from foliar necrosis only after exposure to acidity levels of pH 2.6 or lower. Repeated exposure of lettuce to acidity below pH 2.0 was necessary to reduce yield. The field experiments demonstrated that acidic fog influenced natural incidence of disease. At low pH fog exposure, celery had increased occurrence of basal stalk rot and lettuce exhibited increased bacterial soft rot. Indirect effects of acidic fog on host‐pathogen relationships and subsequent crop marketability may be more important than the direct effects of acidic fog exposure on plant tissue.
The growth, yield and nutrient uptake of winter wheat following root‐pruning
Authors: AYLING SARAH M. 
Published: February 2008

SummaryThe effect of root‐pruning on shoot growth was investigated in winter wheat growing in lysimeters. Removal of half of the root axes at the beginning of stem elongation reduced shoot dry matter, determined 1 month after pruning, by 13% and grain yield by 8%. Removal of either the seminal or nodal root system during tillering reduced shoot dry weight, measured during the growing season, by 7% and grain yield by 25%. Root‐pruning had negligible, or only transient, effects on the concentration of nitrogen, phosphorus, potassium, magnesium and manganese in the shoots. The harvest index was not affected by root‐pruning.
An experimental design and procedures for testing putative controls against naturally‐occurring take‐all in the field
Authors: HORNBY D. , BATEMAN G. L. , PAYNE R. W. , BROWN M. E. , HENDEN D. R. 
Published: February 2008

SummaryIn experiments during 1983–86 take‐all was more severe and eyespot and sharp eyespot less frequent in 2nd‐4th crops of winter wheat at Woburn (Beds.) than at Rothamsted (Herts.). Third crops had most take‐all and yielded least grain. Against this background, small plots, 37 cm × 31 cm, in which all plants were sampled, were tried as a means of increasing experimental precision. They were arranged in fours in incomplete blocks and blocks with complementary treatments (putative controls of take‐all) were paired. Thirty of these block‐pairs were distributed throughout each experimental site in each year to provide one replicate of the design for each of three sampling times: April, June and August. Unattributed variation in disease and plant growth for plots within blocks was compared to that in other strata (block‐pairs and blocks within block‐pairs) of the experiment. The variability amongst block‐pairs scattered throughout the site was nearly always greater than that for blocks within block‐pairs (98% of take‐all assessments, 71% of soil infectivity estimates, 94% of eyespot and sharp eyespot assessments and 86% of all plant measurements). The variability of blocks within block‐pairs exceeded that of plots much less frequently (56% and 69% of take‐all assessments, 33% and 25% of soil infectivity measurements, 63% and 56% of eyespot and sharp eyespot assessments and 50% and 63% of plant measurements; Rothamsted and Woburn, respectively). Small plots were judged mostly on this last comparison, where a variance ratio in excess of 1 indicated that the small plots had decreased variability and increased precision.Variance ratios for different assessments of take‐all indicates that small plots: i) most consistently decreased disease variability during the years of maximum disease, ii) were slightly less effective at Rothamsted than at Woburn, and iii) were usually less effective in fourth crops than in previous crops.Soil infectivity was most uniform after crops with most disease and blocks were rarely more variable than plots. hxcept when disease was severe, soil infectivity in August tended to be positively associated with the yield of the crop just harvested.These findings reveal changes in the scale of disease patterns, both during the crop sequence and within individual crops, and suggest more than one scale of pattern in take‐all‐infested fields. This is discussed in relation to field experimentation and take‐all decline.
Characterisation of watermelon curly mottle virus, a geminivirus distinct from squash leaf curl virus
Authors: BROWN JUDITH K. , NELSON MERRITT R. 
Published: February 2008

SummaryPurified preparations of watermelon curly mottle virus (WCMoV), a whitefly‐transmitted geminivirus, contained dimeric or geminate particles of 20 times 30 nm and the virus was transmissible by mechanical means. Virus yields ranged from 100–150 μg/100 g leaf tissue. Purified preparations exhibited a typical nucleoprotein absorbance profile with a maximum absorbance at 258 nm, and A280 / A260 ratio of 0.61–0.64. Infectivity was associated with two light‐scattering, virus‐containing bands following sucrose density gradient centrifugation. The viral capsid protein was resolved as a doublet by SDS‐PAGE. The estimated mol. wts of the two bands within the doublet were 29 100 (±1550) and 27 733 (±1550), respectively. DNA isolated from virus particles was resolved by gel electrophoresis into two circular single‐stranded DNA bands of approximately 2.6 to 2.7 kb. The two bands are believed to represent the individual components of a bipartite genome, characteristic of previously described whitefly‐transmitted geminiviruses.
Distribution and dynamics of mycophagous and microbivorous nematodes in potato fields and their relationship to some food sources
Authors: HOFMAN T. W. , S'JACOB J. J. 
Published: February 2008

SummaryNematodes are not uniformly distributed in soil. The aim of this study was to investigate the distribution pattern of mycophagous and microbivorous nematodes and to develop sampling methods to detect them at different sites in the soil. Sampling of nematodes was carried out by three methods: using an auger, by collecting soil which was shaken from the roots (root shaking sample) and by collecting roots with the adhering rhizosphere soil (rhizosphere sample). Distribution patterns and population dynamics of mycophagous nematodes were similar to other microbivorous nematodes in three potato fields. Population densities in the rhizosphere samples were 4–50 times higher than those in auger samples. Samples obtained with the auger and root‐shaking methods yielded more or less equal population densities.Numbers of the mycophagous nematodes Aphelenchus avenae, Aphelenchoides sp. and unidentified microbivorous nematodes increased several fold within a few days on suitable substrates in soil. These substrates could be the dying roots of plants of which the haulms were killed or flax straws that were previously colonised by the fungus Rhizoctonia solani.
Effects of leaf‐matter incorporation on Aphelenchoides composticola (Nematoda), mycofloral composition, mushroom compost quality and yield of Agaricus bisporus
Authors: GREWAL P. S. 
Published: February 2008

SummaryIncorporation of dried leaves of Azadirachta indica, Cannabis sativa, Eucalyptus tereticornis and Ricinus communis at 3 kg per 100 kg of dry wheat straw prior to composting had several effects. When compared with controls, treated composts exhibited a higher temperature during composting, a higher nitrogen content and a neutral pH. The treatments resulted in enhanced populations of thermophilic fungi and mesophilic antibiotic‐producing fungi, but reduced numbers of mesophilic competitor/pathogenic moulds. Populations of the mycophagous nematode, Aphelenchoides composticola were reduced below economic injury level in dried leaf treated composts.Compost obtained from C. sativa and R. communis treatments were more rapidly colonised by the mushroom mycelium (Agaricus bisporus) than that from any other treatment. When compared with compost treated with carbofuran R. communis, C. sativa and A. indica treatments significantly increased mushroom yield by 19.4, 8.1 and 6.5% and by 108.5, 88.7 and 85.9% when compared with the control. Yield from the E. tereticornis treatment was also higher than the control but lower than that of the nematicide treatment.
The use of foliage assessment to improve the identification of tolerance to damage by nematodes (Globodera pallida) in potatoes
Authors: DALE M. F. B. , BROWN J. 
Published: February 2008

SummarySix potato trials, two in each of three years, were conducted in collaboration with the Agricultural Development and Advisory Service (ADAS) at sites infested with potato cyst nematodes (G. pallida Pa 2/3). The trials were part of a selective screen to identify PCN tolerant and intolerant clones with each trial consisting of four blocks divided into nematicide treated and untreated sub‐blocks. A range of partially resistant and susceptible material was assessed for yield losses due to PCN damage to the roots and for the effect on the foliage by comparison between the nematicide treated and untreated areas. The relationships between the foliage symptoms, untreated yields, treated yields, proportional yield loss, initial PCN population and the post‐harvest PCN population levels are examined. Significant correlation coefficients were obtained between foliage symptoms and yield of clones in PCN infected soil and also between foliage symptoms with percentage yield loss due to PCN infestation. The conclusions were that the assessment of PCN damage to foliage vigour/development can contribute positively to a more accurate identification of tolerant or intolerant potato genotypes.