Growth analysis of broccoli in relation to fertilizer nitrogen application     

I.M. VÅgen  A.O. SkjelvÅg  H. Bonesmo 《The Journal of Horticultural Science and Biotechnology》2013,88(3):484-492

Summary

Six field experiments with different planting dates over three years in the South of Norway were used to analyse biomass production of broccoli. N was applied at rates of 0, 120, and 240 kg ha^–1. Mineralized N levels in soil before planting differed among the experiments. Crop biomass, leaf area index (LAI), and accumulated intercepted photosynthetically active radiation (PAR) increased with enhanced N rate. So did also radiation use efficiency (RUE), but not significantly from 120 to 240 kg ha^–1. Thus, crop biomass increased to the highest N rate rather by more intercepted radiation than by enhanced RUE. RUE reached saturation level when the sum of applied N and Nmin in soil before planting was about 200 kg ha^–1. There was a strong effect of N application on early plantings, when low temperature and possibly oversaturation of light were the most likely reasons for low LAI, RUE, and RGR at low or no N application. The plant N concentration decreased with increasing biomass over time. Of two alternative relationships of critical N concentration (Nc) suggested by Greenwood et al., the linear one, which gave the higher estimates, fitted better. Both equations were evaluated on the correspondence between a relative N concentration N/Nc = 1 and maximum relative values for: biomass, LAI, accumulated intercepted PAR, and RUE. However, a curvilinear function for Nc might produce a higher correlation over the whole range of plant N concentrations. RUE and accumulated intercepted PAR approached a saturation level at a lower relative N concentration than did biomass and LAI, suggesting that N was more limiting for biomass production than for PAR interception and RUE at N rates below the highest application rate. Incident radiation was fully intercepted at a low LAI, resulting in a low RUE.  相似文献   

Is the ballan wrasse (Labrus bergylta) two species? Genetic analysis reveals within‐species divergence associated with plain and spotted morphotype frequencies          下载免费PDF全文

María QUINTELA  Elin Annie DANIELSEN  Lua LOPEZ  Rodolfo BARREIRO  Terje SVÅSAND  Halvor KNUTSEN  Anne Berit SKIFTESVIK  Kevin A. GLOVER 《Integrative zoology》2016,11(2):162-172

The ballan wrasse (Labrus bergylta) is a marine fish belonging to the family Labridae characterized by 2 main morphotypes that occur in sympatry: spotty and plain. Previous studies have revealed differences in their life‐history traits, such as growth and maturation; however, the genetic relationship between forms is presently unknown. Using 20 recently developed microsatellite markers, we conducted a genetic analysis of 41 and 48 spotty and plain ballan wrasse collected in Galicia (northwest Spain). The 2 morphotypes displayed highly significant genetic differences to each other (F_ST = 0.018, P < 0.0001). A similar degree of genetic differentiation (F_ST = 0.025, P < 0.0001) was shown using the STRUCTURE clustering approach with no priors at K = 2. In this case, the frequency of spotty and plain morphotypes was significantly different (χ² = 9.46, P = 0.002). It is concluded that there is significant genetic heterogeneity within this species, which appears to be highly associated with the spotty and plain forms, but not completely explained by them. Given the previously demonstrated biological differences between morphotypes, and the present genetic analyses, we speculate about the convenience of a taxonomic re‐evaluation of this species.  相似文献   

Early pathogenesis of classical swine fever virus (CSFV) strains in Danish pigs     

Lohse L  Nielsen J  Uttenthal A 《Veterinary microbiology》2012,159(3-4):327-336

Host-virus interactions play an important role for the clinical outcome of classical swine fever virus (CSFV) infections in pigs. Strain virulence, host characteristics and environment are all factors that markedly influence disease severity. We tested CSFV strains of varying virulence in an experimental set-up, reducing the influence of host and environmental factors. Thus, weaner pigs were inoculated with one of 4 CSFV strains in order to compare the pathogenesis for a 3-week-period after infection. CSFV strains selected were 2 new and 2 previously characterized. None of these strains had been tested in Danish outbred pigs before. Clinical observations grouped the infected pigs into two different categories reflecting either non-specific, mainly gastro-intestinal, problems, or severe disease including high fever within the first week after inoculation. Gross-pathological findings varied between strains, however, lymphoid atrophy and growth retardation represented a consistent finding for all 4 strains. Virus distribution, viral load and in particular virus persistence differed, but supported present practice that recommends lymphoid tissue, most optimal tonsil and lymph nodes, as target material to be applied for early laboratory diagnosis. The present study demonstrated constraints associated with early detection of infections with CSFV strains of low virulence. Since neither clinical symptoms nor pathological lesions observed with these strains constituted characteristic signs of CSF, the risk of neglecting a CSF suspicion is immediate. Therefore, topical information on new outbreaks and continuous enhancement of an efficient surveillance system is of great importance to prevent further spread of CSF within the pig population.  相似文献   

Comparing the epidemiological and economic effects of control strategies against classical swine fever in Denmark     

A. Boklund  N. Toft  L. Alban  . Uttenthal 《Preventive veterinary medicine》2009,90(3-4):180-193

In 2006, total Danish pork exports were valued at €3.8 billion, corresponding to approximately 5% of the total Danish exports, and an outbreak of a notifiable disease would have dramatic consequences for the agricultural sector in Denmark. Several outbreaks of classical swine fever (CSF) have occurred in Europe within the last decade, and different control strategies have been suggested. The objective of this study was to simulate the epidemiological and economic consequences of such control strategies in a CSF epidemic under Danish conditions with respect to herd demographics and geography and to investigate the effect of extra biosecurity measures on farms. We used InterSpread Plus to model the effect of nine different control strategies: the minimum measures required by the EU plus depopulation of contact herds (EUplus), extra depopulation of neighbouring herds, extra surveillance within the protection and surveillance zones, extra biosecurity in SPF herds—or in all herds, vaccination of all pigs in the 1 or 2 km zones using live vaccine as a protective measure (vaccination-to-kill), vaccination of all weaners and finishers in the 1 or 2 km zones using an E2 marker vaccine as a suppressive measure (vaccination-to-live). Each epidemic was simulated to start in four different index herds: production herds located in low, medium and high pig density areas, respectively; and a nucleus herd in an area of high pig density. For each control strategy and index case, we calculated the size and duration of the epidemic, the number of depopulated and/or vaccinated herds and animals, the control costs borne by the public and the pig industry, respectively, as well as the loss of exports associated with the epidemic.The simulations showed that the EUplus strategy is the most effective of the evaluated strategies with respect to limiting the size, duration and cost of the epidemic, regardless of the index case. However, regarding the number of slaughtered animals, the vaccination-to-live strategies appeared to be more effective.Epidemics become larger and last longer if the index case is a nucleus herd. This implies that biosecurity in nucleus herds is extremely important to avoid transmission of CSF to these herds.Simulations showed that a Danish CSF epidemic will be moderate in most cases and will include fewer than 10 cases and last less than 2 weeks on average. However, for some iterations, long-lasting and large epidemics were observed. Irrespective of the size and duration, an epidemic is expected to be very costly due to the export losses.  相似文献   

Effect of landscape and population variables on immune response in experimentally introduced bush-cricket populations     

Åsa Berggren 《Landscape Ecology》2009,24(6):749-757

Despite the growing interest in relationships between ecological variables and individual immune function, few empirical data have been available from wild populations. In this study, I assayed the immune response from 370 wild-caught bush-crickets, Metrioptera roeseli, from 20 experimentally introduced populations, by measuring individual encapsulation responses to a surgically implanted nylon monofilament. Bush-crickets descended from populations introduced into larger habitat patches showed a greater immune response when compared to individuals from smaller habitat-area introductions. Also, there was a significant positive correlation between immune response and the amount of linear elements at the introduction site. However, there was a lack of effect of population variables (i.e., propagule size and rate of population growth) on immune response. These results suggest that large-scale environmental parameters, such as patch size and connectivity, can be important for an individual’s physiological health and its ability to defend against disease-causing agents. Such effects are likely to compound the negative impacts associated with isolation of sub-populations and habitat fragmentation.  相似文献   

Pathological and microbiological studies on pneumonic lungs from Danish calves     

Tegtmeier C  Uttenthal A  Friis NF  Jensen NE  Jensen HE 《Zentralblatt für Veterin?rmedizin. Reihe B. Journal of veterinary medicine. Series B》1999,46(10):693-700

During 1 year, the association between microbiological and pathological findings in 72 lungs from calves submitted to the Danish Veterinary Laboratory for diagnostic purposes was studied. All cases were evaluated pathologically and bacteriologically, whereas only 68 cases were examined for the presence of bovine respiratory syncytial virus (BRSV), parainfluenza-3 virus (PI-3 virus) and bovine coronavirus, 62 cases for bovine viral diarrhoea virus (BVD), 45 cases for bovine adenovirus and 51 cases for mycoplasmas. Based on histopathological examination, the cases were diagnosed as fibrinous and/or necrotizing bronchopneumonia, suppurative bronchopneumonia, embolic pneumonia and others. The diagnoses were based on the dominating and most severe lesions in each lung. Haemophilus somnus, Pasteurella multocida, Actinomyces pyogenes, P. haemolytica and BRSV were the most commonly found bacterial and viral lung pathogens, respectively. Pasteurella spp. and H. somnus were often associated with the more severe fibrinonecrotizing type of bronchopneumonia, whereas BRSV was primarily detected in cases of suppurative bronchopneumonia. Mycoplasma bovis was isolated from one case only, whereas M. dispar, M. bovirhinis and Ureaplasma diversum were present, often concomitantly, in the majority of cases. Aspergillus fumigatus was isolated from one case.  相似文献   

Product quality deficiencies in the prefabrication industry for single-family houses     

Åsa Gustafsson  Lars Eliasson 《Wood material science & engineering》2014,9(1):1-11

In the industry for the prefabrication of single-family houses, previous research had indicated that individual companies have problems in securing the product quality of incoming softwood timber. This implies that they need to carry out a quality inspection and adjust the softwood timber when it arrives at their facility in order to fit their production. Opinions within the industry concerning product quality deficiencies differ with regard to the handling procedures and the percentage of perceived deficiencies. However, there are prefabricators of single-family houses that need to find additional areas for use for their purchased softwood timber, and spend several working hours on softwood timber to meet the quality criteria agreed upon. A previous study by Eliasson and Gustafsson puts forward a number of proposals regarding the quality deficiencies of softwood timber in this context. The present work transforms some of these proposals into hypotheses and aims at describing and understanding what affects the perception of product quality deficiencies. Questionnaires were used to collect data. The paper concludes that the purchase volume is indicated to be related to the volume portion of the deficiency in the product quality and that the level of information- and communication-technology support in production (i.e. the degree of automation) is indicated to be related to the inspection activity point. An extension of the proposed hypotheses concludes that the inspection activity point on arrival and/or on delivery into production also affects how companies do perceive product quality deficiencies. Research regarding what affects product quality deficiencies is lacking in recognizing and knowing what is aligned with the perception of product quality deficiencies; the individual companies will have an opportunity to affect and manage their appearance and thereby enhance the use of softwood timber.  相似文献   

Recent changes in the deposition of heavy metals in northern Europe     

Åke Rühling  Germund Tyler 《Water, air, and soil pollution》1984,22(2):173-180

Carpet-forming bryophytes (mosses) have been used extensively since the late 1960's in assessing regional and temporal variability of atmospheric heavy-metal deposition. A large-scale decrease in heavy-metal deposition occurred during the 1970's in Sweden, probably also in other parts of northern Europe. The decrease was closely related to known changes in atmospheric emissions.  相似文献   

Mercury in forest canopy throughfall water and its relation to atmospheric deposition     

Åke Iverfeldt 《Water, air, and soil pollution》1991,56(1):553-564

A seasonal variation of both particle and gaseous Hg concentrations in the atmosphere is present in south-western Sweden. An average gaseous Hg level of 3.7 ng m⁻³ is found in winter, compared to 2.8 ng m⁻³ in summer. A weak decreasing south-north gradient for gaseous Hg in air over the Nordic countries is also present, with yearly average values from 3.2 to 2.8 ng m⁻³. A gradient for particulate Hg is less clear. An air parcel trajectory sector classification of gaseous Hg levels in air, and to some extent the particulate associated Hg, clearly demonstrates the increased concentrations in the southern sectors, especially in south-western Sweden where the gaseous Hg increase is about I ng m⁻³. These observations are consistent with an influence from the European continent. The average concentrations of Hg in precipitation at the various stations show a pronounced decreasing south-north gradient. A major portion of the total Hg present in precipitation is associated with particles. For the southern stations, a strong correlation between Hg and sulfate, or pH, is present suggesting a connection between Hg in precipitation and anthropogenic activities.  相似文献   

Acid reign '95? — Conference summary statement     

H. Rodhe  P. Grennfelt  J. Wisniewski  C. Ågren  G. Bengtsson  K. Johansson  P. Kauppi  V. Kucera  L. Rasmussen  B. Rosseland  L. Schotte  G. Selldén 《Water, air, and soil pollution》1995,85(1):1-14

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