bluuebunny/crossref_metadata_2025_split huggingface dataset:
The expression of resistance to powdery mildew infection in winter wheat cultivars. II. Adult plant resistance
Authors: BENNETT FIONA G. A. 
Published: February 2008

SUMMARYResistance to powdery mildew infection was compared in 18 winter wheat cultivars under field conditions in three seasons, 1977 to 1979. In each year, natural infection occurred from populations of Erysiphe graminis f. sp. tritici containing host‐specific pathogenicity characters matching identified cultivar resistance.Leaves, ears and stems were assessed separately. The expression of resistance in leaves appeared to be independent of that in ears. There were few consistent differences between cultivars in stem infection. Resistance in adult leaves did not necessarily correspond with that in seedling leaves; resistance in ears did not appear to be correlated with plant height.Quantitative differences between cultivars having the same identified resistance characters occurred in both leaves and ears; Flinor, Avalon and Bounty were most resistant on leaves whereas Iona, Wizard and Bounty were most resistant on ears. Differences in background resistance were considered to be responsible for these observations.
Breeding of nodulated red clover (Trifolium pratense) for high yield
Authors: NUTMAN P. S. , RILEY JANET 
Published: February 2008

SUMMARYThe symbiotic effectiveness of four cultivars of red clover were compared and breeding programmes undertaken to increase nitrogen fixation and yield of agar‐ and pot‐grown plants. Programme I used the moderately effective Rhizobium trifolii strain 0403 and Programme II the highly effective strain 5. Aggregate scores of plant size (leaf area) were chosen as the criterion of selection. All cultivars, inoculated with strain 0403, differed in time of initial nodulation and in dry matter yield and three differed in leaf area. None differed in nodule number or N‐content. Dry matter and leaf area were highly correlated. Diallel crosses among highly effective selections in Programme 1 gave progeny yields that exceeded those of crosses between modal selections by averages of 6% in the first generation, 5% in the second generation and 23% in the third generation. Yields of the high cross category exceeded those of the original cultivar by an average of 9% in the second generation and by 25–101% in the third generation. Effects on leaf area were similar. Highly effective progeny tended to nodulate earlier and have more nodules than the remainder but differences were very small. Crosses between cultivars were generally more effective than those within cultivars, indicating heterotic effects. Similar results for yield were obtained in Programme II. The average increase in yield of crosses of third‐generation material between highly effective selections compared with cv. S123 was 63%. The modal crosses were intermediate. In each Programme and generation there were large differences between parents within each cross category.
A model relating yield to individual plant area for predicting growth compensation in Central African field tobacco*
Authors: WIXLEY R. A. J. , SHAW M. J. P. 
Published: February 2008

SUMMARYA model based on the concept of the circle of influence of a plant is used to estimate the relationship between yield and area/plant for tobacco crops with gaps in stand. The model predicts the average yield of plants in any configuration that includes missing plants and is used to predict the economic consequences of loss in stand from pest or other damage.
Losses in the conservation and utilisation of grass and forage crops*
Authors: WILKINSON J. M. 
Published: February 2008

SUMMARYLosses occur during the conservation of forage crops as a result of plant respiration post‐cutting and post‐harvest; as a result of fermentation, surface deterioration, and (in the case of wet crops) effluent production whilst in store. Further losses occur when conserved forages are given to ruminants; the largest being that of undigested material voided in faeces. Losses during conservation and utilisation can be reduced by minimising the period of field drying and using chemical additives to improve preservation or digestibility.
Inhibition of seed germination and development of tomato plants in soil infested with Pseudomonas tomato
Authors: BASHAN Y. , OKON Y. 
Published: February 2008

SUMMARYInfestation of sterilised or natural soil with Pseudomonas tomato at inoculum concentrations of 102 to 109 propagules/ml inhibited germination of seeds and caused damping‐off of tomato cv. VF‐198, susceptible to bacterial speck. Infestation with saprophytic P. fluorescens at an inoculum concentration of 109 propagules/ml did not cause any damage. Germination of seeds of tomato cv. Rehovot‐13, resistant to P. tomato, was not affected in P. tomato‐infested natural soil, but was inhibited when tested in P. tomato‐infested, sterilised soil. Tomato plants which were symptomless from sowing to the flowering stage when growing in infested soil had 20–30% less foliage than plants growing in uninfested soil.
Studies on rose mosaic disease in field‐grown roses produced in the United Kingdom
Authors: THOMAS B. J. 
Published: February 2008

SUMMARYArabis mosaic virus (AMV) and prunus necrotic ringspot virus (PNRSV), separately or together, caused in field‐grown roses the range of symptoms recognised as rose mosaic disease. PNRSV infection alone generally induced chlorotic line patterns, ring‐spots or mottles in the leaves at some time during the growing season; AMV plus PNRSV normally caused chlorotic vein‐banding. However, during prolonged periods of high temperatures (c. 21 °C or more) vein banding occurred in some roses infected only with PNRSV.Isolates of PNRSV from rose had particles which were similar in shape, protein mol. wt, density and sedimentation coefficients to previously described isolates of PNRSV from cherry, plum and rose; all were cherry serotypes.In graft‐inoculated roses, apple serotypes of PNRSV induced stunting and chlorosis, puckering and distortion of leaves, which closely resembled symptoms associated with rose mosaic in the USA and chlorotic mottle rose mosaic in New Zealand.To avoid possible confusion in using the name rose mosaic it is suggested that the virus(es) present in roses should be named.
Rapid indexing of the sunblotch disease of avocados using a complementary DNA probe to avocado sunblotch viroid
Authors: PALUKAITIS PETER , RAKOWSKI ANDREW G. , ALEXANDER DONALD McE. , SYMONS ROBERT H. 
Published: February 2008

SUMMARYA routine procedure has been established for the sensitive and specific detection of avocado sunblotch viroid in partially purified nucleic acid extracts of avocado leaves by hybridisation analysis with 32P‐complementary DNA prepared against the purified viroid. Avocado sunblotch viroid was shown to be present in 12 avocado trees that had indexed positive in a biological test for sunblotch disease but was absent from 10 trees that indexed negative. The complete correlation between sunblotch disease and the presence of viroid indicates that the complementary DNA hybridisation assay procedure can be used for the indexing of sunblotch disease. The overall procedure of leaf extraction and hybridisation analysis can be completed in 5 days and is to be compared with up to 2 yr required for indexing by biological methods.The level of avocado sunblotch viroid in partially purified nucleic acid extracts of a number of different sources of sunblotch infected avocado leaves was found to vary 10 000‐fold from 0.2% to 2 × 10‐5% by weight. The lower limit of detectability of the viroid by the hybridisation assay is considered to be about 10‐5% by weight; this is at least 103 times more sensitive than the detection of the viroid by polyacrylamide gel electrophoresis of the leaf nucleic acid extracts followed by staining.
Application of rapid biochemical methods for detecting avocado sunblotch disease
Authors: ALLEN R. N. , DALE J. L. 
Published: February 2008

SUMMARYThe method of Palukaitis & Symons (1980) for extracting low molecular weight ribonucleic acids from plant tissue was improved by CF‐11‐cellulose chromatography and further simplified for use in routine biochemical indexing for avocado sunblotch viroid (ASBV). Extracts were prepared routinely at 10 g dry weight equivalents (DWE) of tissue per ml; more concentrated than previously possible with many avocado cultivars. Conditions for assaying extracts of ASBV were standardised and the lower limits for detection determined as 80–230 ng ASBV/g DWE of tissue for polyacrylamide gel electrophoresis (PAGE) and 1 ng/g DWE of tissue for complementary DNA (cDNA) probe assays. The concentration of ASBV in a single infected tree varied from 5 to 5000 ng/g DWE between branches, but only to a minor degree between mature leaves and young blossoms within branches.Six independent sources of sunblotch disease were examined and all proved positive for ASBV by PAGE. The ASBV extracted from five of these sources hybridised with cDNA prepared from the sixth or standard source (Hass/SB‐1), with hybridisation values ranging from 43% to 89%. In a survey of 76 trees intended for propagation in Australia, all of 17 trees previously accepted as healthy on the basis of graft transmission tests were negative for ASBV by PAGE and had cDNA hybridisation values ranging from 1.8% to 12.1%. Amongst 59 trees apparently free of sunblotch symptoms but not previously indexed, only one tree was positive for ASBV by both PAGE and cDNA probe assay. The other 58 trees were negative by PAGE but had hybridisation values ranging from 1.0% to 42.8%. Forty‐nine trees had values consistent with known healthy trees (<12% hybridisation), while the results of the remaining nine trees will require confirmation by additional tests before a conclusion about ASBV is made.The cDNA probe assay successfully detected ASBV in avocado seedlings graft inoculated with Hass/SB‐1, 1–2 months before symptoms were displayed but not until 6 months after inoculation. Methods for improving the cDNA probe assay still further are discussed.
Rooted leaf cuttings as an aid in screening for resistance to Plasmodiophora brassicae
Authors: WILLIAMSON CYNTHIA J. 
Published: February 2008

SUMMARYRooted leaf cuttings were used to screen a range of genotypes and cultivars from Brassica spp. and Raphanus sativus for resistance to Plasmodiophora brassicae. The optimum conditions for obtaining equivalent disease incidence and disease severity on leaf cuttings and on seedlings were investigated.In the method used leaves were cut near the base of the petiole before the lamina was fully expanded. They were kept in a mist propagator for 6 to 18 days and then transferred to a clubroot test bench and individually inoculated with a suspension of resting spores. There was an optimum period for each cultivar between cutting and inoculation which gave the maximum incidence of infection: c. 15 days for Doon Major (swede); 10–15 days for Civasto (stubble turnip) and Giant Rape (forage rape); c. 22 days for Maris Kestrel (marrow stem kale) and c. 10 days for Slobolt (fodder radish). Gall size on rooted leaf cuttings gave a quantitative measure of disease severity equivalent to that on seedlings in tests using the European Clubroot Differential host set, the five above‐mentioned cultivars and four swede cultivars. There was little callus production except on some B. campestris hosts and on cuttings with shoot tissue; microscopic examination was used to confirm the presence or absence of infection in galls.Hormone rooting powder did not increase the rate of root production in two cultivars of forage rape. Root development was less extensive in B. campestris than in B. oleracea or B. napus. Apparently normal shoots developed on 96% of leaf cuttings (inoculated and uninoculated) in which a fragment of axillary bud tissue was included. The results are discussed in relation to screening for resistance in whole plants and in tissue culture.
The consistency of the resistance of eight carrot cultivars to carrot fly attack at several centres in Europe
Authors: ELLIS P. R. , HARDMAN J. A. 
Published: February 2008

SUMMARYEight carrot cultivars representing the range of resistance to carrot fly damage as assessed in England were grown at 12 sites in five European countries in 1977 and in 1978. The trials provided evidence of agreement with the findings in England for both years in the ranking of cultivars with respect to their resistance to carrot fly damage. The Nantes cultivar Clause's Sytan Original was the most resistant cultivar tested. Consistent results were obtained from sites where carrots were assessed at harvest and carrot fly attack was severe. A significant interaction between sites and cultivars was largely due to sites where carrots were stored prior to assessment.
Perennation in woody fruit plants and its relationship to carbohydrate turnover
Authors: PRIESTLEY C. A. 
Published: February 2008

SUMMARYCarbohydrates constitute the principal reserves in temperate woody fruit plants and are depleted during winter, particularly around the time of bud‐break before new growth makes good the losses. Movement of reserves between underground and aerial parts occurs during winter. All perennial parts show alternate depletion and replenishment but root extremities may undergo irreversible depletion and die. Interconversions between soluble carbohydrates and polysaccharides indicate a balance between degradation and synthesis. High growth potential is associated with high starch/starch + sugar ratio.
Some observations in west Wales on the relationships between numbers of alate aphids and weather
Authors: A'BROOK JOHN 
Published: February 2008

SUMMARYSome preliminary associations are reported between monthly totals of cereal aphids (Metopolophium dirhodum, Rhopalosiphum insertum, R. padi and Sitobion avenae) caught in suction traps and weather data. Catches at 1.2 and 12.2 m during the summer and autumn flight peaks from 1969 to 1979 were compared with combinations of prior monthly totals of rainfall and accumulated day‐degree temperatures. The best models fitting these results are reported and proposed for testing against future data. The possible relevance of these models, for forecasting whether measures for the control of barley yellow dwarf virus in autumn‐sown cereals are necessary in any year, are discussed.
Association of Phytophthora palmivora bark canker and insect damage in cocoa in Papua New Guinea
Authors: PRIOR C. , SMITH E. S. C. 
Published: February 2008

SUMMARYBark canker caused by the fungus Phytophthora palmivora has caused the death of many cocoa trees over 15 years old in Papua New Guinea in recent years. Cankers are significantly associated with channels made by the larvae of bark‐damaging insects, which provide the major entry point for the pathogen. The combination of canker and insect damage may limit the economic life of cocoa to less than 15 years in affected areas.
Forecasting barley mildew development in West Scotland
Authors: CHANNON A. G. 
Published: February 2008

SUMMARYObservations on plots of spring barley cv. Golden Promise during May‐July 1973–79 showed that escalation of mildew commenced in mid‐June 1976, in late June in 1973 and 1974, in early July in 1978 and 1979, and failed to develop in 1975 and 1977. By mid‐July there was 40% infection in 1976, and 13–21% infection in 1973, 1974, 1978 and 1979. Less than 2% mildew occurred in 1975 and 1977.Using as a basis the method of mildew forecasting formulated by Polley & King (1973), it was found that once mildew was established in the crop there was moderately good association between the incidence of high mildew risk according to the Polley weather criteria and the major peaks of spore concentration above the crops. It was not possible to correlate these two features during May and early June each year because of a lack of inoculum, but it is considered that the failure of mildew to develop during the entire growing seasons of 1975 and 1977, in spite of frequent high risk periods, was due in part to low atmospheric humidity during the early part of the season. The relative number of accumulated Polley factors satisfied on days when the relative humidity approx. 1 m above ground was 78% or more (at 0900 GMT) during the period mid‐May to mid‐June, separated the low mildew years of 1975 and 1977 from the moderate ones of 1973, 1974, 1978 and 1979, and the severe mildew year of 1976. This procedure may provide a practical means of forecasting the level of mildew build‐up during the later growth stages of the barley crop.
Resistance of cocoa to swollen‐shoot virus in Ghana. I. Field trials
Authors: LEGG J. T. , LOCKWOOD G. 
Published: February 2008

SUMMARYIn Ghana, field resistance to cocoa swollen‐shoot virus (CSSV) in young, bearing trees was assessed by monitoring natural spread by mealybug vectors from adjacent graft‐inoculated line sources. Apparent rates of virus spread were estimated by regressing proportions of infected trees on time from inoculation. In some hybrids between parents derived from Upper Amazonian material, spread was only 25–40% that in currently recommended varieties. This resistance is the most effective, feasible measure to reduce economic losses and the resistant hybrids could be made available quickly for large scale use.The results from trials in which virus spread most rapidly were the easiest to interpret. Spread of CSSV is erratic, necessitating large experiments, and in trials with equal replication the largest plots gave the greatest precision. Neighbouring plot adjustment proved unsatisfactory as it improved precision but appeared to reduce accuracy.
Resistance of cocoa to swollen‐shoot virus in Ghana. II. Assessment of seed inoculation experiments
Authors: LOCKWOOD G. 
Published: February 2008

SUMMARYDifferences in amounts of infection following seed inoculation, by the mealybug vector (Planococcoides njalensis (Laing)) of cocoa swollen‐shoot virus were used as a short‐term test of virus resistance in a range of cocoa progenies. The test results were highly correlated with virus resistance as measured in field trials. The best assessment of seed inoculation experiments allowed for progeny‐dependent variation in the latent period of the virus. Experiments in which estimates of progeny means varied significantly with replicate sometimes gave poor agreement with known field performance.
The effect of cereal growth stage and feeding site on the reproductive activity of the bird‐cherry aphid, Rhopalosiphum padi
Authors: LEATHER S. R. , DIXON A. F. G. 
Published: February 2008

SUMMARYApterous Rhopalosiphum padi on the first leaf of cereal plants, developed faster and were more fecund at seedling to stem extension of barley, at tillering to earing of oats and at stem extension and earing of wheat. Feeding site on a mature plant also affected the rate of development and fecundity of the aphids; the largest and most fecund developed on the stems of oat and wheat plants. The consequences of these variations in reproductive performance are discussed in relation to the population dynamics of R. padi and its possible pest status in Britain.
The effect of iprodione on seed germination and seedling emergence in onion
Authors: ENTWISTLE A. R. , BROCKLEHURST P. A. , JONES T. G. 
Published: February 2008

SUMMARYIprodione seed treatment at 100 g a.i./kg seed had little effect on final emergence in peat‐based compost at 60% moisture content (wet weight basis) but caused up to 1.5 days' delay in the time to 50% of the final emergence (t50). The effect was independent of initial seed viability, the conditions and duration of seed storage after treatment and germination temperature. Raising the compost moisture content to 70% resulted in a 9% reduction in final emergence and a 3 day increase in t50.Iprodione had a greater effect in a filter paper test, reducing final emergence by up to 24% and increasing t50; the effects were again independent of initial seed viability and storage conditions.
The reactions of some Brussels sprout F1 hybrids and inbreds to cauliflower mosaic and turnip mosaic viruses
Authors: TOMLINSON J. A. , WARD C. M. 
Published: February 2008

SUMMARYVirus infection of Brussels sprout crops was widespread in Britain in 1974–76. Infected plants contained mostly cauliflower mosaic (CaMV) and turnip mosaic (TuMV) viruses but occasionally broccoli necrotic yellows virus (BNYV) was also found. The most seriously affected cultivar was the F1 hybrid cv. Fasolt. Other hybrids including cvs Achilles, Citadel and King Arthur were more tolerant of infection.A key was developed for assessing the reactions of various F1 hybrids and their parent inbred lines to CaMV + TuMV. Tests showed that the mean symptom severity of hybrids was usually less than the mean symptom severity of the parent inbreds, indicating that resistance to infection is partially dominant.The reactions of infected inbreds grown in winter under glasshouse conditions (15–18°C) were closely correlated with those of plants grown in the field. Thus, rapid selection of virus‐tolerant inbreds can be made under glasshouse conditions.
Responses of cow pea (Vigna unguiculata) varieties and their hybrids to variation in day and night temperature regimes
Authors: DOTO A. L. , WHITTINGTON W. J. 
Published: February 2008

SUMMARYThe effects of each of four contrasting combinations of two day (30, 26°C) and two night (24, 19°C) temperatures were studied on four cowpea varieties and their F1 hybrids. Early vegetative development was enhanced by the higher day, higher night temperature and flowering occurred first in plants receiving this treatment. The hybrids showed marked heterosis for leaf area but not for time to flowering. The ten genotypes studied showed correlated responses to increases in night temperature and differed in the degree of their response. The extent of the response (or stability) of varieties was often determined by the character values in the environment with the highest yield and heterotic hybrids were the least stable. Grain yield was highest in the lower day temperature environments but there was variation between genotypes in whether this occurred at the lower or higher night temperature. The pattern of responses shown by hybrids agreed with those of their parents indicating that stability was an inherited character. The results confirmed and extended those in earlier studies and emphasised the importance of a greater understanding of the nature of responses to the environment in selecting new varieties.
The cytokinin activities of 6‐α‐alkylbenzyloxypurines
Authors: WILCOX E. J. , SELBY C. , WAIN R. L. 
Published: February 2008

SUMMARYThe homologous series of 6‐α‐n‐alkylbenzyloxypurines with alkyl groups (—(CH2)nCH3) from n = 0 to n = 11 have been prepared and examined in three tests for cytokinin activity. The parent benzyloxypurine was also included in the tests.Substituting methyl (n = 0) into the methylene group of 6‐benzyloxypurine removed activity almost completely; thereafter, increasing the size of the alkyl group (n = 1–5) gave compounds which were active in all tests, the butyl (n = 3) and pentyl (n = 4) derivatives being more active than 6‐benzyloxypurine itself. Activity then fell as the series was ascended; the higher homologues (n = 8–11) being completely inactive.The results are discussed in relation to steric and other considerations.
Post‐harvest treatments for the control of Phytophthora syringae storage rot of apples
Authors: EDNEY K. L. , CHAMBERS D. A. 
Published: February 2008

SUMMARYOospores of Phytophthora syringae germinating at 10 and 15°C under artificial light formed one or more sporangia, which yielded zoospores. Furalaxyl and metalaxyl demonstrated eradicant action against infections occurring on zoospore‐inoculated apples. Control was obtained at 10°C when treatment was delayed 5–11 days after inoculation.Storage in 5% CO2+ 3% O2 and 0% CO2+ 2% O2 reduced rotting compared with storage in air.