bluuebunny/crossref_metadata_2025_split huggingface dataset:
Serological detection of ryegrass mosaic virus and ryegrass seed‐borne virus
Authors: CHESTER IRENE B. , HILL S. A. , WRIGHT DAPHNE M. 
Published: February 2008

SUMMARYRyegrass mosaic virus (RMV) was reliably detected in both perennial (S24) and Italian (S22) ryegrass, by enzyme‐linked immunosorbent assay (ELISA) when plants had been infected for 8 wk. ELISA detected more infections in field‐grown perennial ryegrass cv. Premo than either visual assessment or electron microscopy. However, with plants of Italian ryegrass cultivars only recently infected with RMV, positive reactions were more difficult to separate from the reactions of RMV‐free plants, which varied considerably with cultivar, some giving high absorbance values. Immunosorbent electron microscopy showed that the RMV antiserum also contained antibodies to ryegrass seed‐borne virus (RGSV), suggesting that these high values were caused by RGSV infection in the material tested.
Comparison of nucleic acid hybridisation and other tests for detecting tobacco rattle virus in narcissus plants and potato tubers
Authors: HARRISON B. D. , ROBINSON D. J. , MOWAT W. P. , DUNCAN G. H. 
Published: February 2008

SUMMARYAll isolates of tobacco rattle virus (TRV) found in naturally infected narcissus leaves produced nucleoprotein particles, mostly in large concentrations but, because of antigenic diversity, less than half of the isolates were identified by immunosorbent electron microscopy (ISEM) and still fewer by enzyme‐linked immunosorbent assay. All were identified by a nucleic acid hybridisation test in which DNA complementary to RNA‐1 of strain PRN of TRV was allowed to react with nucleic acid extracted from leaf tissue.Spraing‐affected tubers in some potato stocks yielded only NM isolates of TRV. These isolates do not produce virus particles and they were therefore not detected by ISEM. The infectivity of nucleic acid extracts from recently harvested tubers with spraing symptoms was much greater than that of extracts prepared from tubers after 8 months' storage. In other potato stocks, some spraing‐affected tubers contained NM isolates and the rest contained particle‐producing isolates (M isolates) of TRV. The infectivity of sap and of nucleic acid, extracted 7 months after harvest from tubers infected with M isolates, was much greater than that of nucleic acid extracted from comparable tubers infected with NM isolates. TRV was detected by nucleic acid hybridisation in extracts of almost all tubers containing either M or NM isolates, even when the tubers were not tested until 7–8 months after harvest. The probable sequence of events occurring after tubers are infected with TRV is outlined, and it is suggested that the virus will rarely become established in fields as a result of planting infected tubers.
Inheritance and sources of resistance to bacterial speck of tomato caused by Pseudomonas syringae pv. tomato
Authors: FALLIK E. , BASHAN Y. , OKON Y. , CAHANER A. , KEDAR N. 
Published: February 2008

SUMMARYInheritance of resistance to bacterial speck of tomato was determined by analysing F1 F2 and backcross progenies of crosses involving a susceptible (VF‐198) and a resistant cultivar (Rehovot‐13). The results fit the hypothesis that resistance is controlled by a single dominant gene in interaction with minor genes. Cultivar susceptibility to Pseudomonas syringae pv. tomato was tested under greenhouse conditions under high inoculum pressure using infested tomato seeds together with infested soils and spray‐inoculated wounded plants. Of 21 species, cultivars and lines, Rehovot‐13, Ontario 7710 and Lycopersiconpimpinellifolium P.I. 126927 were found to be resistant to the pathogen. VF‐198 and Tropic‐VF were the most susceptible. Extra Marmande, Saladette, Acc.339944–3 and the wild type Lycopersicon esculentum var. cerasiforme were moderately resistant.
Uptake and distribution of nitrogen in wheat plants supplied with different amounts of nitrogen after stem elongation
Authors: PEREZ PILAR , MARTINEZ‐CARRASCO R. , PUENTE L. SANCHEZ DE LA 
Published: February 2008

SUMMARYThe uptake of nitrogen and its distribution between shoots and between organs within shoots in wheat (Triticum aestivum) was studied from the start of stem elongation to 28 days after anthesis in a glasshouse experiment with eight nitrogen levels between 0·1 and 12·8 mequiv./litre.There was no net uptake of nitrogen in plants supplied with 0·8 mequiv./litre or less; with more nitrogen the absorption increased linearly. Twenty to 44% of the total plant nitrogen was absorbed after anthesis, this fraction increasing with nutrient supply. The nitrogen allotted to the main shoot decreased until the onset of anthesis and increased thereafter at the expense of the tillers, except with 12·8 mequiv./litre, where nitrogen percentage in the main shoot decreased also after anthesis. Raising nitrogen supply increased the proportion of plant nitrogen recovered in the tillers.Nitrogen accumulated in the ear after emergence and by the 28th day after anthesis it contained between 52% and 73% of the total plant nitrogen. The ear of the main shoot had a higher proportion of shoot nitrogen than that of the tillers. The fraction of ear nitrogen supplied by retranslocation decreased from almost 100% with 0·8 mequiv. N/litre or less to nil with 12·8 mequiv./litre. Increasing nitrogen application decreased the fraction of total nitrogen allocated to the ear.
Factors determining the microflora of stored barley grain
Authors: HILL R. A. , LACEY J. 
Published: February 2008

SUMMARYColonisation of barley grain has been studied during storage at different water contents and with and without restriction of the air supply to simulate conditions in unsealed silos. Grain stored with a water activity >0·9 aw (20% water content) heated spontaneously when aeration was unrestricted, the maximum temperature attained increasing with aw to 58 °C at 1·0 aw (39% water content). The presence of many unripe grains increased the tendency to heat at a given mean water content. Although heating was prevented by sheeting to restrict the air supply, it could occur subsequently when the sheeting was removed. Both heating and restriction of the air supply were associated with increased carbon dioxide (to >25%) and decreased oxygen concentrations (to <5%). Germination of grain after 6·9 months storage was correlated with aw; germination levels approaching 100% were retained only at about 0·7 aw (13·5% water content). Colonisation by Aspergillus species was correlated with aw and temperature and similar correlations with Penicillium species were also found, with P. verrucosum var. cyclopium abundant at 0·85‐0·90 aw (17·20% water content) and P. piceum, P. funiculosum and P. capsulatum at 0·90‐0·95 aw (20–25% water content). In sealed containers P. roquefortii occurred at 1·00 aw (39% water content) and P. hordei at 0·90‐0·92 aw (20–22% water content). Spores of fungi and actinomycetes formed during spontaneous heating of grain survived 6 months sealed storage although Absidia corymbifera and Micropolyspora faeni may have declined in numbers. Fungicides applied to the ripening grain had only limited effect on the colonisation of the grain during storage.
Resistance reactions of Cucumis melo to inoculation with Pseudoperonospora cubensis
Authors: REUVENI R. 
Published: February 2008

SUMMARYReactions of several cultivars and breeding lines of melons to artificial inoculation at the seedling stage with a local isolate of Pseudoperonospora cubensis were compared under growth chamber and field conditions. Four different reactions were distinguishable: highly susceptible, susceptible, partially resistant and resistant. The differences in the reactions were more clear‐cut under growth chamber conditions. Selection for resistance could be carried out at the seedling stage using sporangia production and lesion size, shape, colour and number as criteria. Under growth chamber conditions, plants of resistant lines had minimal sporangia production and circular or angular lesions 1–2 cm in diameter which became necrotic within 5 days after inoculation.
Interactions between seed priming treatments and nine seed lots of carrot, celery and onion. II. Seedling emergence and plant growth
Authors: BROCKLEHURST P. A. , DEARMAN JANE 
Published: February 2008

SUMMARYSamples of three seed lots of each of three cultivars of carrot, celery and onion were primed in polyethylene glycol solution for two weeks at 15 °C. Seedling emergence was recorded in the field for carrot and onion and in the glasshouse for celery. Compared to the untreated control, priming increased the percentage seedling emergence in certain poorly‐emerging seed lots of carrot and celery, but had no effect on onion. Mean emergence times were reduced by priming in all seed lots, by 3–5, 5–8 and 3–9 days in carrot, celery and onion respectively. The largest effects occurred in the slowest‐emerging seed lots. There were significant interactions between priming and seed lots within cultivars in carrot and celery and between priming and cultivars in celery and onion. Priming generally reduced the spread of emergence times, but the effects were not statistically significant in carrot.Drying back the primed seeds had no effect on percentage emergence in onion, but reduced it (compared to primed seed which had not been dried‐back) in certain carrot and celery seed lots. Primed and dried‐back seeds emerged later than primed seeds, by up to 1·5, 2·6 and 2·6 days in carrot, celery and onion respectively. The spread of emergence times was generally larger for primed and dried‐back seeds than for primed seeds, but the differences were not always statistically significant.Plant fresh weights were recorded 9, 7 and 12 wk after sowing for carrot, celery and onion, respectively. In each species, mean plant weight was inversely related to seedling emergence time; thus plants grown from primed seed were always heavier than the controls, by up to 33%, 182% and 47% in carrot, celery and onion respectively.
The effect of barley yellow dwarf virus on field populations of the cereal aphids, Sitobion avenae and Metopolophium dirhodum
Authors: AJAYI BY OLUPOMI , DEWAR A. M. 
Published: February 2008

SUMMARYThe numbers of cereal aphids, especially Metopolophium dirhodum in 1979, and Sitobion avenae in 1980, were significantly increased on BYDV infected wheat and oats in 1979, and wheat, barley and oats in 1980.The differences were probably caused by attraction of alates of each species to virus infected plants which had changed colour as a result of their infection. Significantly more alates of M. dirhodum were found on virus infected oats in 1979, and of S. avenae on oats and barley in 1980, although not on wheat in either year. probably because the colour contrast in wheat was less intense than in the other crops.Flight chamber experiments with alates of both species confirmed their visual attraction to virus‐infected leaves. The interaction between virus, vector and host plants is discussed with reference to the ecology of virus spread.
A comparison of inoculation methods for determining potato cultivar reaction to black leg
Authors: HOSSAIN M. , LOGAN C. 
Published: February 2008

SUMMARYTwo methods of inoculating tubers, one by dipping them in an aqueous suspension of Erwinia carotovora subsp. atroseptica, the other by inserting the end of a wooden toothpick charged with undiluted bacteria into the rose‐end near a sprout, were compared over two years for their ability to produce black leg and for their effect on plant growth and yield on a number of cultivars chosen because of expected differences in susceptibility. Although both methods produced a similar rank order for cultivar reaction, the more consistent results were obtained using the toothpick method, clear differences in black leg incidence and yield being evident between the susceptible cultivars Ulster Sceptre and Maris Bard and the more resistant Pentland cultivars. As some cultivars appear more tolerant to black leg than others, yield may be as important a criterion as disease incidence when assessing overall cultivar performance.The inoculation of the base and middle of stems and the infiltration of the bacterium into tubers were also investigated as alternative methods for assessing cultivar susceptibility.
The effect of Erwinia carotovora subsp. atroseptica (blackleg) on potato plants. I. Growth and yield of different cultivars
Authors: LAPWOOD D. H. , LEGG PHILIPPA R. 
Published: February 2008

SUMMARYThe effect of planting seed tubers inoculated either near the stolon attachment (heel end), among the eyes at the apex (rose end) or mid‐way along the tuber with Erwinia carotovora subsp. atroseptica, was assessed in terms of growth of the plant, disease symptoms and yield. Invariably rose‐end inoculation had the greatest and heel‐end the least effect in decreasing yield when compared with uninoculated plants. Cultivars Majestic and King Edward were the most susceptible, Pentland Crown showed some resistance to invasion of stems (blackleg) although plant vigour, expressed in terms of plant height and stem number was affected and Maris Piper was the most resistant.
The effect of Erwinia carotovora subsp. atroseptica (blackleg) on potato plants. II. Compensatory growth
Authors: ADAMS M. J. , LAPWOOD D. H. 
Published: February 2008

SUMMARYIn field experiments in 1981 and 1982, uninoculated seed tubers (cv. Désirée) and those inoculated with Erwinia carotovora subsp. atroseptica at the rose (apical) or heel (stolon attachment) ends were planted at normal (35 cm) or double spacing; in additional plots, inoculated and uninoculated tubers were planted alternately.Inoculation, especially at the rose end, decreased plant height and sometimes resulted in blackleg symptoms. Individual plant yields were recorded at the end of the season. In plots of uniform seed type at normal spacing, inoculation decreased total yield compared with uninoculated by 12–13% (heel‐end inoculation) or 26–40% (rose‐end inoculation). At double spacing, yields increased compared with normal spacing by 44–58% (uninoculated or heel‐end inoculation) or 30–39% (rose‐end inoculation). When rose‐end‐inoculated and uninoculated seed tubers were planted alternately, inoculated plants yielded less and uninoculated plants more than in plots planted throughout with the same seed treatment. The abilities of inoculated and uninoculated plants to compensate for weak or missing neighbours were combined using equations to predict the yields of crops with different proportions of diseased or missing plants.
Improved methods for the purification and detection of cocoa swollen shoot virus
Authors: ADOMAKO D. , LESEMANN D.‐E. , PAUL H. L. , OWUSU G. K. 
Published: February 2008

SUMMARYThe extraction of cocoa swollen shoot virus (CSSV) from cocoa leaves with pectinase, purification from the concentrated extracts by filtration through Celite and Sepharose 2B, and concentration of the virus by isopycnic CsCl centrifugation are described. The pectinase and Celite treatments effectively removed mucilage and particulate host plant materials, and enhanced the release of virus particles, Isopycnic CsCl centrifugation resulted in 10–100‐fold concentration of particles, but with apparent loss of infectivity.After extraction with pectinase, CSSV particles were regularly seen by electron microscopy in sap. Immunosorbent electron microscopy (ISEM) considerably enhanced the detection of CSSV in sap. The particles were bacilliform or bullet‐shaped and of various lengths. The common dimensions were 142 × 27 nm.
The influence of straw disposal and cultivation regime on the population dynamics ofBromus sterilis
Authors: FROUD‐WILLIAMS R. J. 
Published: February 2008

SUMMARYThe effects of straw‐burning and cultivation regime upon the population dynamics of a naturally‐occurring infestation of Bromus sterilis were investigated over a period of 11 months. Both grain and straw of the original crop were seriously contaminated with seeds of this species.An initial population of 12 635 seeds m‐2 declined by 85% between July and late August in uncultivated stubble without straw‐burning, but only 44% of seeds gave rise to seedlings. A further 10% had produced seedlings by late December and another 5% emerged between February and April. By April no viable seed remained.Straw‐burning destroyed 97% of the ungerminated seeds on the soil surface and reduced seedling numbers by 94%. However, those seedlings which did survive formed many tillers and produced considerable quantities of seed.Shallow cultivation reduced the seed population by 34% and in April there were 47% fewer seedlings on these plots than on direct drilled ones. Ploughing to a depth of 20 cm eradicated the weed; and although buried seeds germinated, they failed to emerge.Seedlings emerging in spring failed to flower before harvest. Detailed laboratory investigation showed that although B. sterilis does not have a pronounced requirement for vernalisation, chilling did accelerate flowering, while long‐day photoperiods were required for panicle extension. Only germinated seeds responded to the vernalisation stimulus.
The genetical control of incomplete forms of resistance to Erysiphe graminis in spring barley
Authors: ASHER M. J. C. , THOMAS W. T. B. , THOMAS C. E. 
Published: February 2008

SUMMARYEight spring barley lines exhibiting incomplete resistance to powdery mildew in field trials were crossed and back‐crossed to a common susceptible parent to produce the basic generations (P1 P2, F1 F2, B2 B2) required for a genetical investigation. By means of joint scaling tests, disease assessments on adult plants in a field trial were used to estimate the genetic parameters contributing to resistance. Lines with major genes, which appeared partially resistant due to the presence of corresponding virulence, were characterised by the presence of a significant dominance component in the analysis. Partially resistant lines which either lacked identifiable major genes or with major genes that were ineffective in the trial, but with good background resistance, could also be distinguished. Significant additive and epistatic effects were detected in all crosses. The prospect of enhancing partial resistance through hybridisation and selection is discussed.
The effect of gibberellins on the storage life of plantains
Authors: GEORGE J. B. , MARRIOTT J. 
Published: February 2008

SUMMARYDipping plantain fruits in gibberellins (GA4/7 or GA3) delayed the ripening of individual fruits by approximately 50%, the two treatments being equally effective. Measurement of the preclimacteric period (PCP) by increased respiration showed that plantain fruits vacuum infiltrated with GA4/7 (10‐5 M) gave an extension of 37% in the PCP under high humidity. No effect was observed at low humidity. The use of gibberellins on plantain storage is discussed.
Effects of temperature, light, nitrate and pre chilling on seed germination of grassland plants
Authors: WILLIAMS E. D. 
Published: February 2008

SUMMARYThe effects of factorial combinations of alternating (20/10 oC) and constant temperature (20 oC), of light (intermittent) and dark, and of distilled water and nitrate on the germination of a range of species of indigenous grassland were investigated in 1979, and in 1980 when the effects of pre‐chilling were also studied.Species differed greatly in their response to the eight sets of environmental conditions in 1979. With the exception of Lolium perenne ssp. perenne and Cynosurus cristatus, only a small percentage of seeds of most species was able to germinate in constant temperature in the dark. However, when light was supplied there was moderate germination of Anthoxanthum odoratum, Cerastium fontanum ssp. glabrescens, Festuca rubra, Holcus lanatus and Poa trivialis. Alternating temperature greatly increased the germination of most species and nitrate further increased germination of Agrostis capillaris, Deschampsia caespitosa, H. lanatus, Poa annua and P. trivialis. In alternating temperatures, light increased germination of these species even more than did nitrate. A. capillaris, D. caespitosa and P. annua required all three factors for maximum germination, and another 7% of seeds of A. capillaris also required gibberellic acid. Germination responses following sequential application of factors often differed from those resulting from simultaneous treatment: in particular, the germination of Ranunculus species was greatly enhanced.Although seeds of the species tested in 1980 were more germinable than those of the same species in 1979, they responded similarly to the different factors. Light increased the germination of both Taraxacum officinale and Plantago lanceolata in constant but not in alternating temperature, while nitrate was much more stimulatory to the latter species. About half the seeds of P. lanceolata were dormant. Pre‐chilling at 4oC for 7 days increased subsequent germination of all species when followed by constant temperature, except of A. capillaris in the dark and C. cristatus (already maximal) in the light. When followed by alternating temperature in the dark, pre‐chilling greatly decreased germination of A. capillaris. In the light, where germination of most species was maximal, there was little effect of pre‐chilling. Longer durations (21 and 42 days) of chilling of older seed gave similar results to the 7 day pre‐chilling.
Evidence that maize wallaby ear disease is caused by an insect toxin
Authors: OFORI F. A. , FRANCKI R. I. B. 
Published: February 2008

SUMMARYColonies of the leafhopper Cicadulina bimaculata were established from single male and female insects raised from surface sterilised eggs and shown to be free of leafhopper A virus (LAV). Insects from these colonies were as capable of inducing maize wallaby ear disease (MWED) in maize seedlings as those with LAV indicating that the virus is not involved in the etiology of MWED.Maize seedlings colonised by C. bimaculata in glasshouse trials developed initial MWED symptoms within 6–8 days of infestation. The symptoms intensified thereafter and many plants died after more than 16 days' exposure, even after the insects were killed with insecticide. However, when freed from the insects before symptoms became very severe, plants recovered and assumed normal growth. These observations support the view that MWED is caused by an insect toxin.
Aerated‐steam treatment for control of Alter nana tenuis on lobelia seed
Authors: HALL T. J. , TAYLOR G. S. 
Published: February 2008

SUMMARY Alternaria tenuis may cause severe seedling blight, damping‐off and leaf spotting of the bedding plant lobelia. Disease transmission from seed naturally and artificially infected by A. tenuis was demonstrated and the pathogenicity of four isolates established. Soaking of lobelia seed in 0–2% thiram suspension at 30 oC for 12 h adversely affected the rate of germination and did not consistently reduce infection to acceptable levels. Treatment with aerated steam at 50–51 oC for 15–20 min reduced seed infection to undetectable or insignificant levels and caused only slight damage to the seed. In glasshouse trials seed treated with aerated steam performed significantly better than seed soaked in thiram suspension both in terms of germination and foliage production.