bluuebunny/crossref_metadata_2025_split huggingface dataset:
Survival of Alternaria brassicae and Alternaria brassicicola on crop debris of oilseed rape and cabbage
Authors: HUMPHERSON‐JONES F. M. 
Published: February 2008

Summary Alternaria brassicae and A. brassicicola lesions present on infected leaves of oilseed rape and cabbage placed outdoors on soil produced viable spores for as long as leaf tissues remained intact. For oilseed rape this was up to 8 wk and for cabbage up to 12 wk. On leaves exposed in November and January spore concentrations decreased with time but on leaves exposed between April and June spore concentrations increased up to 9‐fold in the first 4–6 wk and then declined. On stem sections of seed plants of oilseed rape and cabbage similarly placed on the soil, the fungi produced viable spores for up to 23 wk with spore concentrations increasing up to 11‐fold in the first 6–8 wk after harvest. These results indicate that infected debris of brassica crops remaining on the ground after harvest may provide a source of dark leaf spot infection which may be implicated in the spread of the disease within and between crops.
Preparation and evaluation of dehydrated mycological media from West African raw materials
Authors: AWUAH R. T. 
Published: February 2008

SummaryTwelve culture media powders prepared from local raw materials were evaluated for their mycological utility using Nigrospora oryzae as the initial test organism. Radial growth of N. oryzae was greater (P < 0.05) on media from pigeon pea, soybean and ripe plantain than on Oxoid potato‐dextrose agar (PDA) control. Two other media supported radial growth comparable to potato‐dextrose agar. More conidia were produced on the ripe plantain medium (44/microscope field) than on PDA (3.4/microscope field). In an additional test, Fusarium oxysporum f. sp. cubense, Aspergillus niger, Curvularia lunata and Choanephora cucurbitarum grew and sporulated well on selected media. Local media were inexpensive and easy to produce but tended to be characterised by reduced clarity and presence of particles after autoclaving and jelling.
Changes in relative abundance of two potato cyst nematode species Globodera rostochiensis and G. pallida in one generation
Authors: MARSHALL J. W. 
Published: February 2008

SummaryChanges in relative abundance of the two potato cyst nematode species Globodera rostochiensis and Globodera pallida were studied during the 1983/84 season at two different population levels in small pots in the glasshouse and at a single population density on plants grown outdoors in 2 litre terylene cloth bags.In both environments G. rostochiensis was the more successful species. Although the ratio of the two species changed and G. pallida was at a lower level at the end of the experiment it was never eliminated. However, when the number of G. pallida in the mixture was small it did better than expected and demonstrated a frequency dependent response.
The inheritance of floral characters in white clover (Trifolium repens)
Authors: HILL J. , NORRIS I. B. , MICHAELSON‐YEATES T. P. T. 
Published: February 2008

SummaryA diallel cross was carried out among seven varieties of white clover to investigate the inheritance of some of those characters which affect potential seed yield. Peduncle length and number of seeds/floret have low narrow‐sense heritabilities, while peduncle length displays the added complications of heterozygosity and non‐allelic interactions. Consequently, improvements in these characters will be difficult. Seed number m‐2 is a composite character which apparently exhibits heterozygosity. Higher seed yields will therefore be obtained by selection for its component characters, particularly floret number and floral density, both of which are apparently inherited in a comparatively straightforward manner. These results are discussed in the context of improving the potential seed yield of white clover.
Variability in response of potato cultivars to micropropagation.: In vitro performance
Authors: CALIGARI P. D. S. , POWELL W. 
Published: February 2008

SummaryThe variation in response of 23 cultivars to temperature and sucrose level was investigated for in vitro shoot cultures of potato. It was found that both temperature and sucrose level had a significant effect but in terms of the interactions with cultivars that temperature was the more important. The means and components of variation for the different treatments were examined to reveal the potential for selecting a treatment combination giving optimal expression of the characters measured to assess growth of the micropropagated plantlets. In the case of rapid multiplication systems, a high mean response for number of usable nodes combined with a low cultivar component of variation (i.e. a high response uniformly over cultivars) would be desirable. This combination of character expressions was generally achieved, in the present study, when cultures were raised at 20°C with 3% sucrose in the medium.
Variability in response of potato cultivars to micropropagation
Authors: POWELL W. , BROWN J. , CALIGARI P. D. S. 
Published: February 2008

SummaryThe field performance of 23 cultivars exposed to various tissue culture regimes was evaluated in the presence of appropriate controls. There were significant differences between cultivars but more importantly there were significant interactions between cultivar and treatments. The largest interaction effect was consistently clones x field vs micropropagated seed tubers and was found to be highly significant (P < 0.001) for all variates examined. In general, there was little agreement between the performance of cultivars when grown from explant‐derived seed tubers and when they were grown from field‐produced seed. This study demonstrates the potential problems associated with the phenotypic selection of tissue culture derived material in a potato breeding programme.
Respiratory changes in yam storage tissue (Dioscorea spp.) infested with Meloidogyne incognita using a novel technique for measuring oxygen uptake
Authors: FAWOLE B. , EVANS A. A. F. 
Published: February 2008

SummaryA simple, novel application is described which measures the oxygen uptake in respiring tissues using an electrochemical gas sensor to monitor volume concentration changes in ambient oxygen with output to a chart recorder. Oxygen uptake by white yam, Dioscorea rotundata cvs Nwopoko and Obioturugo; and yellow yam, D. cayenensis (cv. Ukom Manu) which were heavily infected with root‐knot nematode, was significantly higher than in the non‐infected tissue. However, the rate of oxygen uptake in D. rotundata was significantly higher than in D. cayenensis.
The effects of gibberellin A3 on white clover during floral development
Authors: NORRIS I. B. 
Published: February 2008

SummaryThe effects of gibberellin A3 (GA3) application on the white clover variety Olwen were assessed in the field. Timing of application in relation to developmental stage was also examined.Gibberellin A3 at a concentration of 100 mg litre‐1 increased the number of reproductive buds per stolon, the peduncle length and the number of seeds per head. Application at flower bud emergence or at the beginning of peduncle extension gave the greatest increase in these characters.Gibberellin A3 also increased the number of nodes per stolon, stolon length and petiole length.
Effects of seed‐bed conditions on slug numbers and damage to winter wheat in a clay soil
Authors: GLEN D. M. , MILSOM N. F. , WILTSHIRE C. W. 
Published: February 2008

SummaryIn a field experiment three levels of consolidation were combined with three seed‐bed tilths, to produce nine different types of seed‐bed. The soil properties of each combination of tilth and consolidation were measured and effects on the numbers and biomass of slugs in the top 10 cm of soil and on damage to wheat seeds and seedlings were assessed. Eight species of slug were present, with three species predominating (Deroceras reticulatum, Arion distinctus and Arion subfuscus). Between 3% and 33% of seeds and seedlings were killed by slugs (recorded at Growth Stage 12). Contrary to expectation, most damage occurred on consolidated seed‐beds of fine or medium tilth, least on loose seed‐beds of the same texture; intermediate damage occurred on cloddy seed‐beds, where consolidation had little effect. The level of damage occurring on different types of seed‐bed was directly related to the biomass of slugs in the top 10 crn of soil, and was inversely related to depth of sowing and the percentage of fine soil in the seed‐bed. These three factors together accounted for 94–97% of the variance in slug damage. Consolidation was associated with increased slug damage probably because of its effects on these three factors: slug biomass was greater and seed was at shallower depth in consolidated than loose seed‐beds and consolidation, whether before or after drilling, failed to break down clods of soil into finer particles. This is the first experimental evidence in the field of the effects of seedbed conditions on slug numbers and damage to winter wheat and represents a significant step towards forecasting and avoiding slug damage in this crop.
Sampling techniques, spatial distribution and cultural control of millet spike worm, Raghuva albipunctella (Noctuidae: Lepidoptera)
Authors: GAHUKAR R. T. 
Published: February 2008

SUMMARYSpike washing and direct count methods were equally effective for sampling eggs and young larvae of millet spike worm, Raghuva albipunctella (Noctuidae: Lepidoptera) in Senegal, but spike washing is a more economical method. Most eggs (70%) were laid on emerging millet spikes and the spike apex was the preferred oviposition site. Most larvae pupated 10–30 cm from millet hills. The maximum number of pupae was found in the upper layer (< 10 cm) in loamy soil and deeper (20–30 cm) in sandy soil. Ploughing fields after millet harvest reduced the population of spike worm pupae significantly, but may prove impracticable or socially unacceptable to farmers.
Effects of the paedogenetic mushroom cecid, Heteropeza pygmaea (Diptera:Cecidomyiidae) on cropping of the cultivated mushroom (Agaricus bisporus)
Authors: WHITE P. F. 
Published: February 2008

SUMMARYWhen introduced into a mushroom crop at rates of 2, 20 or 200 larvae/tray (0.56 m2), the mushroom cecid, Heteropeza pygmaea, caused significant reductions in both yield and number of mushrooms in relation to the infestation level. The reductions were greater when the larvae were introduced at spawning rather than at casing. The yield and number of infested (unmarketable) mushrooms increased significantly in relation to the initial infestation level.Just two H. pygmaea larvae, introduced at spawning, resulted in cecid populations that caused a 12% loss in total yield in addition to a 7% loss due to spoilage. Loss assessment in the future, therefore, should take into account both yield suppression and spoilage.There was little effect of cecid infestation on flush timing and mushroom size was only affected in the fourth flush, when a significant reduction (27%) was shown at the highest infestation rate at spawning.
A field study of the relationship between pre‐planting density of Globodera pallida and the growth and yield of two potato cultivars of differing tolerance
Authors: TRUDGILL D. L. , MARSHALL B. , PHILLIPS M. 
Published: February 2008

SUMMARYNon‐resistant but tolerant cv. Cara and non‐resistant but relatively intolerant cv. Pentland Dell were grown in split plots encompassing a range of population densities of potato cyst nematode, Globodera pallida. Light interception and its efficiency of conversion were estimated by regular ground cover measurements and plant harvests. It was concluded that increasing levels of infestation with G. pallida only slightly decreased the efficiency of utilisation of intercepted radiation. Heavy infestation of G. pallida initially decreased the top growth and light interception of both cultivars by similar proportions, but in later harvests, this adverse effect markedly decreased for Cara whereas it slightly increased for Pentland Dell. This difference was due to the heavily infested Cara eventually achieving and maintaining 100% ground cover whereas the equivalent Pentland Dell never exceeded 75% ground cover. Consequently, final tuber yields were decreased much more for Pentland Dell than for Cara though the decreases in tuber yield were less than those for top growth. The importance of nematode effects on top growth, and hence on light interception, with regard to both yield losses and tolerance differences, were clearly demonstrated. Both linear and logarithmic models were used to describe the relationship between the initial population density of G. pallida and yield, and the implications of differences in tolerance on the parameters in the logarithmic model are discussed.
Investigation of the relationship between seed leachate conductivity and the germination of Brassica seed
Authors: THORNTON JANET M. , POWELL ALISON A. , MATTHEWS S. 
Published: February 2008

SUMMARYLarge differences in the leachate conductivities of single seeds after 24 h soaking were observed in five Brussels sprout cultivars. Within each cultivar non‐germinable seeds tended to have higher conductivities than germinable seeds, but the conductivity above which seeds failed to germinate varied between cultivars. No conductivity reading or partition value could therefore be considered as an absolute boundary between germinable and non‐germinable seeds to allow the prediction of seed germination for all seed lots of the same species. However, the mean conductivity for each sample was significantly correlated with germination (r = 0.83, P < 0.05) and was clearly higher for samples with lower germinations. Differences in the partition values for the five cultivars may have been attributable to the natural age of the seeds. Seeds of Asmer Aries artificially aged rapidly at 20% moisture content for up to 48 h at 45° C showed increasing leachate conductivity with increased time of ageing (r = 0.97, P < 0.01) and decreased germination (r = ‐ 0.88, P < 0.05). Again however the values for germinable and non‐germinable seeds of different artificial ages varied. Leakage from seeds was limited by the testa in the first 6 h of imbibition. Solute leakage from embryos of the five cultivars was therefore greater than those for intact seeds but a clear separation of germinable and non‐germinable seeds was still not possible from the conductivity readings. The implications of the observed increases in conductivity with increased seed age and decreased germination for the development of a rapid vigour test for small seeded vegetables in conjunction with controlled deterioration are discussed.
The response of an autumn‐sown determinate faba bean to different plant distributions
Authors: PILBEAM C. J. , HEBBLETHWAITE P. D. , RICKETTS H. E. 
Published: February 2008

SUMMARYThe response of an autumn‐sown determinate selection, 858, to different plant distribution patterns was examined in field trials during the two seasons 1985/86 and 1986/87 at the University of Nottingham. Plants were sown at two densities (20 and 40 plants per m2) and at three different row widths (11.9, 23.8 and 47.6 cm) in the autumn of each season.Plant numbers and combined yields were greater in 1986/87 than in 1985/86. Grain yield was unaffected by differences in inter‐row spacing and this was ascribed to the early attainment of complete ground cover even when plants were grown in widely spaced rows. Yield was most strongly correlated with seed numbers per m2.An examination of yield on a per plant basis suggested that narrow inter‐row spacings were more productive at low plant densities, while yield per plant was greater at higher densities if the crop was grown on wider inter‐row spacings. It was concluded that autumn‐sown determinate forms of faba bean were able to compensate for large changes in plant distribution and consequently yield was unaffected.
Inhibition of degreening in the peel of bananas ripened at tropical temperatures.
Authors: BLACKBOURN H. D. , JEGER M. J. , JOHN P. , THOMPSON A. K. 
Published: February 2008

SUMMARYChanges in the plastid ultrastructure as revealed by thin‐section electron‐microscopy, chlorophyll a/b ratio, and the polypeptides of the thylakoid chlorophyll‐protein complexes have been examined during the degreening of bananas (Musa AAA Group, Cavendish Subgroup) and plantains (Musa AAB Group, Plantain Subgroup) ripened at 20°C and 35°C. In bananas, where degreening is inhibited at temperatures above 24°C, ripening at the higher temperature results in a retention of thylakoid membranes, a relatively delayed breakdown in chlorophyll b, and a reduced dismantling of pigment‐protein complexes. By contrast, in plantains, where degreening is complete within 4 days at both 20°C and 35°C, thylakoid membranes and their associated pigment‐protein complexes are lost, and there is a rapid increase in chlorophyll a/b ratios at both ripening temperatures. It is suggested that the retention of thylakoid membranes is an important factor in the failure of Cavendish bananas to degreen when ripened at tropical temperatures, and that the degreening problem may be related to the comparatively high chlorophyll b content of the preclimacteric fruit.
Assessing the risk of primary infection of cereals by barley yellow dwarf virus in autumn in the Rennes basin of France
Authors: GILLET H. , DEDRYVER C. A. , ROBERT Y. , GAMON AGNES , PIERRE J. S. 
Published: February 2008

SUMMARYIn the Rennes basin, Rhopalosiphum padi is anholocyclic and represents more than 90% of suction trap catches of potential vectors of barley yellow dwarf virus (BYDV) during autumn. From 1983 to 1987 the possibility of predicting the risk of BYDV infection of batches of barley test seedlings (sampling units) exposed each week from September to December near a 12.2 m high suction trap was investigated. Three kinds of variables were checked as possible predictors: weekly mean or maximum temperatures; weekly catches of R. padi (including or excluding males); and percentage of sampling units infested by aphids.Three contrasting examples were observed: during the first three years (1983–1985), infection was high and its change with time followed temperature, aphid catches and plant infestation changes; in 1986, high numbers of aphids caught and a high proportion of plants infested resulted in only low infection and in 1987, both infestation and infection were very low.Simple linear regression analysis showed that the more reliable predictors of infection were the proportion of infested plants and to a lesser extent the numbers of trapped aphids. Multiple linear regressions including either of the three groups of ‘predicting’ variables did not result in any improvement in the prediction.At a practical level, the use of counts of aphid catches would seem a better compromise between accuracy and consistency of prediction and ease of gathering data than that of plant infestation but any significant improvement of the prediction should be sought in an early estimate of the amount of virus available to aphids before they colonise the plants.
Injury to oilseed rape caused by mirid bugs (Lygus) (Heteroptera: Miridae) and its effect on seed production
Authors: BUTTS R. A. , LAMB R. J. 
Published: February 2008

SUMMARYInjury by Lygus spp. to oilseed rape, Brassica napus L. and Brassica campestris L., was assessed based on laboratory and field studies in Alberta, Canada. The visible injuries consisted of lesions on the surfaces of stems, buds, flowers and pods similar to those described for other crops. They caused buds and flowers to abscise and seeds to collapse, and reduced the weight of healthy seeds produced per pod. The plants compensated for bud loss so that no net reduction in the number of pods occurred. However, in some situations the damage to buds resulted in a reduced seed yield that increased with the amount of injury. The plants also compensated for flower loss so that no net reduction in the number of pods occurred, but seed yield declined as injury increased. Plants did not compensate for seeds that collapsed as a result of lygus feeding. The feeding activity of lygus bugs reduced seed yield in oilseed rape.
Epidemiology of Cladosporium allii and Cladosporium allii‐cepae, leaf blotch pathogens of leek and onion.
Authors: JORDAN MARY M. , BURCHILL R. T. , MAUDE R. B. 
Published: February 2008

SUMMARYConidia of Cladosporium allii and C. allii‐cepae germinated over the temperature range 2–30°C on agar with optimal responses at 15–20°C (C. allii) and 20°C (C. allii‐cepae). Conidia of both fungi germinated in water and at c. 100% relative humidity (r.h.) but not at lower humidities on leaf and glass slide surfaces. Germination was more rapid when spores were applied dry to agar or leaves than when applied in water or nutrient solution. More lesions developed when conidia of C. allii‐cepae were deposited dry on onion leaf discs or leaf surfaces than when they were applied suspended in water. Conidia of both fungi required 18–20 h at c. 100% r.h. to germinate and infect when applied dry to leaves. Damaging the leaves or the addition of nutrients to the leaf surface increased the incidence of infection by C. allii‐cepae compared to controls. Inoculated onion bait plants placed out‐of‐doors developed infection after at least 17 h at c. 100% r.h. or with leaf wetness. Similar conditions were necessary for infection of bait plants exposed in onion and leek crops infected by C. allii‐cepae and C. allii respectively. Disease development and spread of infection occurred at different rates over the same period in two different cultivars of leeks, with spore concentrations increasing in proportion to disease. Spore numbers in the air fell considerably when infected leeks were ploughed under.
Plant parasitic nematodes associated with the roots of wind toppled trees at the Royal Botanic Gardens, Kew
Authors: HOOPER D. J. , WEBB R. M. , FLYNN CORINNA 
Published: February 2008

SUMMARYRoot and soil samples from 21 trees blown down in Kew Gardens during the gales of October 1987 yielded 29 species of plant parasitic nematodes. Pratylenchus crenatus, P. thornei and P. penetrans were the only endoparasitic nematodes found. The common occurrence of P. crenatus and the root ectoparasitic nematodes, such as Merlinius microdorus, Paratrichodorus pachydermus and Rotylenchus robustus reflected the predominantly sandy nature of most of the soil samples. Species rarely recorded in Britain included Hemicriconemoides pseudobrachyurum, Paralongidorus maximus and Xiphinema pseudocoxi, all of which may be introductions.
Strategies for control of eyespot (Pseudocercosporella herpotrichoides) in UK winter wheat and winter barley
Authors: FITT B. D. L. , GOULDS A. , HOLLINS T. W. , JONES D. R. 
Published: February 2008

SUMMARYThis review considers strategies for control of eyespot (Pseudocercosporella herpotrichoides) in winter wheat and winter barley in the UK. Varietal resistance to eyespot may take the form of direct resistance to the growth of the pathogen in the stem base or of indirect tolerance to eyespot through resistance to lodging. The French variety Cappelle‐Desprez has been a source of resistance for most UK wheat varieties and a new source of resistance in wild goat grass has been discovered recently. Use of fungicides for control of eyespot increased rapidly after the introduction of the highly effective MBC fungicides in the 1970s, but has decreased recently because UK populations of P. herpotrichoides are now predominantly resistant to MBC fungicides and alternative fungicides are more expensive. Historically, cultural methods, especially crop rotation, have been important in the control of eyespot. The importance of cultural control of eyespot is now increasing because more non‐cereal break crops are being grown and fungicide use is declining.