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11.
J. J. Colls J. J. J. Wiltshire C. J. Wright M. H. Unsworth 《Water, air, and soil pollution》1995,85(3):1343-1348
Ash trees were exposed to ozone episodes (150 nl l?1, 8 h d?1, 24–27 d y?1) from May to October, 1992 to 1994, in open-top chambers designed to minimise microclimatic modification. Many aspects of growth were studied, including leaf abscission, leaf area, mean leaf size, tree height and girth, extension growth, cross sectional area of annual rings and above-ground dry weight. An overview of the results is presented. This shows that the duration of the leaf fall period was increased by exposure to ozone. However, three seasons of severe ozone exposure relative to UK conditions did not significantly alter other aspects of growth. 相似文献
12.
Recently, artificially constructed metamaterials have become of considerable interest, because these materials can exhibit electromagnetic characteristics unlike those of any conventional materials. Artificial magnetism and negative refractive index are two specific types of behavior that have been demonstrated over the past few years, illustrating the new physics and new applications possible when we expand our view as to what constitutes a material. In this review, we describe recent advances in metamaterials research and discuss the potential that these materials may hold for realizing new and seemingly exotic electromagnetic phenomena. 相似文献
13.
A.R. McKemey D.M. Glen C.W. Wiltshire W.O.C. Symondson 《Soil biology & biochemistry》2006,38(9):2903-2909
Molecular ecology techniques are increasingly used to study invertebrate foodwebs and trophic interactions in the field. However, the study of subterranean foodwebs is currently constrained by the difficult, laborious and often expensive methods that need to be employed to simply measure invertebrate population densities accurately. Here we describe and field-test a novel monoclonal antibody-based system for tracking slug populations. Proteins were extracted from soil blocks using sodium chloride and a new slug-specific monoclonal antibody was developed, capable of detecting the proteins liberated by the salt. Detection sensitivity and limits, using enzyme-linked immunosorbent assays (ELISA), were measured for a range of soils and the system proved to be effective, whether the soil was heavy clay or sandy. The sensitivity of the assay varied between soils and needed to be calibrated by ELISA. There was a linear relationship between slug biomass in any given soil and slug proteins detected by ELISA. A field experiment was performed comparing ELISA with the most accurate conventional approach. The latter involved taking blocks of soil from the field and flooding them gradually over 10 days to drive slugs to the surface, where they were collected and weighed. Parallel blocks of soil were taken 1 m away and subjected to the salt extraction/ELISA approach. Results using the two systems proved to be very similar, but ELISA produced results more rapidly. The many advantages of using ELISA to measure slug density are discussed. 相似文献
14.
Do UK crops and grassland require greater inputs of sulphur fertilizer in response to recent and forecast reductions in sulphur emissions and deposition? 
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下载免费PDF全文 J. Webb C. Jephcote A. Fraser J. Wiltshire S. Aston R. Rose K. Vincent B. Roth 《Soil Use and Management》2016,32(1):3-16
UK emissions of sulphur dioxide decreased by 94% between 1970 and 2010 and are projected to decrease by another 50% by 2020 as coal fired power stations are decommissioned. We used the Community Multiscale Air Quality model to create maps of sulphur (S) deposition to assess the impact of these forecast decreases in S emissions on net S deposition to crops in England and Wales. Currently, average S deposition, net of S leaching, varies little between the UK regions, being greatest in Yorkshire and Humberside (Y&H), at ca. 5–6 kg/ha S, and least in Wales, at ca. 3–4 kg/ha S. However, even in Y&H S deposition is no more than 25% of S uptake by cereals and only ca. 10% of S uptake by oilseed rape (OSR). By 2020, net S deposition is predicted to decrease by between 30 and 60% and will be no more than 15% of S uptake by cereal crops and <10% of S uptake by OSR. We conclude that, with the exception of a few localities, net S deposition is currently making only a minor contribution to crop S requirements and this small contribution will continue to decline. We recommend S be applied at the rates currently advised, as either mineral fertilizer or livestock manures (or a combination of both), to all crops and grass grown on sandy soils or in areas of >375‐mm overwinter rainfall. The need for S fertilizer appears to be greatest for grass swards cut more than once. 相似文献
15.
Wiltshire MC 《Science (New York, N.Y.)》2001,292(5514):60-61
16.
Jessica Jamuna Buss James Owen Harris Jason Elliot Tanner Kathryn Helen Wiltshire Marty Robert Deveney 《Journal of fish diseases》2020,43(2):227-237
The haplosporidian Bonamia was first detected in Australian shellfish in 1991. Australian isolates in Ostrea angasi Sowerby, 1871 were identified as Bonamia exitiosa Hine, Cochennac and Berthe, 2001, which threatens development of an O. angasi aquaculture industry. European field data suggest that Bonamia ostreae Pichot, Comps, Tigé, Grizel and Rabouin, 1980 infections in Ostrea edulis Linnaeus, 1758 build slowly, but infection dynamics of B. exitiosa in O. angasi are unknown. We investigated B. exitiosa infection in O. angasi by cohabiting uninfected juvenile O. angasi with adults infected with B. exitiosa. Oysters were sampled at 10, 21 and 40 days after cohabitation, and B. exitiosa prevalence and intensity were assessed. Bonamia exitiosa rapidly infected and caused disease in O. angasi. Mortalities began at 12 days, with ˜50% mortality by day 21 and >85% mortality by day 40. Mortalities displayed pathology consistent with clinical B. exitiosa infection. Time to first infection is likely influenced by a combination of parasite infectivity, host exposure and host immune capacity. Host death is not required for transmission, but probably facilitates release of parasites from decaying tissue. Understanding B. exitiosa transmission informs design and interpretation of field studies and aids development of management strategies for oyster aquaculture. 相似文献
17.
The life-cycles of three willow beetle pests, Phratora (= Phyllodecta) vulgatissima, Phratora (=Phyllodeeta) vitellinae and Galerucella lineola (Coleoptera, Chrysomelidae), were investigated during 1994–95 in a plantation of short-rotation coppiced willows (Salix viminalis cv. Bowles Hybrid) at Long Ashton, Bristol, UK. The P. vulgatissima had one generation during the year. Overwintered adults emerged from hibernation in April and after a short feeding period, copulation and egg-laying occurred. Larval stages were found from May–July. The new generation of adult beetles appeared in July–August and fed for a while before hibernating. Hibernating adults were found in hedgerows around the site and in the plantation on willow stools and ground vegetation. Dispersal of adult beetles between feeding and overwintering sites appeared to be fairly localized. Hence, crop management strategies that reduce the potential for overwintering in and around plantations may help to minimize spring re-invasion and damage. Although based on limited observations, the biology of P. vitellinae and G. lineola appeared similar to that of P. vulgatissima. However, there is evidence in the literature that both these species, unlike the latter, can have a partial second generation in some years. The potential effect of insect herbivory on the growth and biomass yield of S. viminalis cv. Bowles Hybrid was investigated experimentally by artificial hand-defoliation of pot-grown plants. Yield losses were strongly correlated with the amount and time of defoliation. Results indicated that even slight or moderate damage by insect herbivores could have a significant impact on the biomass productivity of coppiced willows. 相似文献
18.
Jessica Jamuna Buss Kathryn Helen Wiltshire James Owen Harris Jason Elliot Tanner Marty Robert Deveney 《Journal of fish diseases》2020,43(3):359-369
Bonamia spp. cause epizootics in oysters worldwide. In southern Australia, Bonamia exitiosa Hine, Cochennac and Berthe, 2001 threatens aquaculture of Ostrea angasi Sowerby, 1871. Bonamia spp. infections can display strong seasonality, but seasonal dynamics of B. exitiosa–O. angasi are unknown. Ostrea angasi naïve to B. exitiosa infection were stocked onto farms in three growing regions, and B. exitiosa was monitored seasonally for one year. Environmental parameters we measured did not correlate with B. exitiosa prevalence or infection intensities. Extreme temperatures suggest O. angasi culture systems need development. Bonamia exitiosa prevalence increased over time. After three months, O. angasi had B. exitiosa prevalence of 0.08–0.4, and after one year, the prevalence was 0.57–0.88. At some sites, O. angasi had >0.5 B. exitiosa prevalence in >6 months, but at other sites, >9 months passed before prevalence was >0.5. Bonamia exitiosa infection intensities were low with no seasonal pattern but were affected by the interaction of site, season and oyster meat:shell ratio. Understanding infection and initiating a breeding programme for resistance would provide benefits for O. angasi industry expansion. 相似文献
19.
R. Sylvester-Bradley E. Lord D.L. Sparkes R.K. Scott J.J.J. Wiltshire J. Orson 《Soil Use and Management》1999,15(1):1-8
Abstract. Precision farming is the process of adjusting husbandry practices within a field according to measured spatial variability. In this review, we explore the prospects for precision farming using the principles that underly conventional soil management and agronomy. The cost-effectiveness of precision farming is determined by the cost of defining zones within fields, the stability of zones through time, the difference in treatment between zones in terms of cost, and the responsiveness of the crop in terms of yield and quality to changes in treatment. Cost-effective precision farming is most likely where prior knowledge indicates large heterogeneity and where treatment zones can be predicted, for example from soil type or field history. Soil related factors are likely to provide the main basis for precision farming because they tend to be stable through time and influence crop performance. In particular, soil mapping may usefully indicate the moisture available for crop growth, organic matter maps may be utilized for precision application of fertilizers and soil acting herbicides, and variation in soil pH can be mapped and used as a basis for variable lime application. However, comprehensive nutrient mapping is less likely to be economic with existing techniques of chemical analysis. The value of yield mapping lies in identifying zones which are sufficiently stable to be of use in determining future practices. Maps of grain quality and nutrient content would significantly augment the value of yield maps in guiding marketing decisions and future agronomy. Interactions between soil differences and seasonal weather are large, so yield maps show considerable differences from season to season. Interpretation of such maps needs to follow a careful, informed, analytical process. Extensive and thorough field experimentation by crop scientists over many years has shown that yield variation arises as a result of a large and complex range of factors. It is highly improbable that simple explanations will be appropriate for much in-field yield variation. However, the capacity to sense yield variability within fields as opposed to between fields, where there are many confounding differences, provides an opportunity for the industry to improve its understanding of soil-based effects on crop performance. This should support its decision taking, whether through precision farming or through field-by-field agronomy. The main obstacle to the adoption of precision farming is the lack of appropriate sensors. Optimal sensor configurations that will measure the specific needs identified by end-users need to be developed. The conclusions reached in this paper probably apply to farming throughout northern Europe. 相似文献
20.
In a laboratory experiment, grey field slugs (Deroceras reticulatum) were introduced to trays of clay soil drilled with wheat seeds at 10 or 25 mm depth. Trays were left without molluscicide, or methiocarb pellets were drilled with the seeds or placed on the surface of the soil immediately after drilling. In the absence of molluscicide, there was less damage to seeds drilled at 25 mm than at 10 mm. Methiocarb pellets drilled with seeds at 10 mm depth killed slugs and reduced damage to seeds and seedlings, but the percentage of seeds killed was similar to the percentage of deeper-drilled seeds killed where no molluscicide had been applied. Pellets drilled with deeper-sown seeds did not kill slugs, or reduce damage to seeds and seedlings, whereas pellets placed on the soil surface immediately after sowing were effective in killing slugs and reducing plant damage irrespective of drilling depth. The best protection from slug damage was provided by deeper drilling combined with pellets broadcast on the soil surface. In a field experiment, methiocarb pellets broadcast immediately after drilling at two depths killed slugs and protected seedlings from damage, whereas pellets drilled with seeds were ineffective because seed-bed conditions prevented slugs from reaching seeds and pellets (only 4% of seeds were killed by slugs in the absence of molluscicide treatment). The implications of these results for slug control and for non-target fauna (wood mice and ground beetles) are discussed. 相似文献