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91.
Detailed root and shoot development of bareroot and container Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedling stocktypes were compared during the first growing season after outplanting. The study was installed in raised beds with ideal environmental conditions and at a field reforestation site. Survival at both sites was 98% and did not differ between stocktypes. Seedlings were excavated in spring (5, 8, 12, and 16 weeks after planting) and in fall (35, 40, and 45 weeks after planting). In spring, container seedlings had more numbers of new roots and greater new root and shoot biomass than bareroot seedlings at both sites. In fall, bareroot seedlings consistently averaged more new root growth (though nonsignificant) than container seedlings suggesting that stocktype differences may not continue long-term. Container seedlings had significantly greater water percent than bareroot seedlings at the field site (all sample dates) and the raised bed site (weeks 5, 8, and 40 only). Regardless of environmental conditions or season, seedlings at both sites maintained water percent between 60 and 70% of fresh weight. Seedlings grown in the raised beds had much greater growth than those grown in the field. However, relative growth patterns for the two stocktypes were very similar on each site. The data generated establish baseline differences between stocktypes for root initiation, growth, and allometry during the first year after planting. Challenges associated with root development research are discussed.  相似文献   
92.
Elevated nitrogen (N) deposition can affect litter decomposition directly, by raising soil N availability and the quantity and quality of litter inputs, and indirectly by altering plant community composition. We investigated the importance of these controls on litter decomposition using litter bags placed in annual herb based microcosm ecosystems that had been subject to two rates of N deposition (which raised soil inorganic N availability and stimulated litter inputs) and two planting regimes, namely the plant species compositions of low and high N deposition environments. In each microcosm, we harvested litter bags of 10 annual plant species, over an 8-week period, to determine mass loss from decomposition. Our data showed that species differed greatly in their decomposability, but that these differences were unlikely to affect decomposition at the ecosystem level because there was no correlation between a species’ decomposability and its response to N deposition (measured as population seed production under high N, relative to low N, deposition). Litter mass loss was ~2% greater in high N deposition microcosms. Using a comprehensive set of measurements of the microcosm soil environments, we found that the most statistically likely explanation for this effect was increased soil enzyme activity (cellobiosidase, β-glucosidase and β-xylosidase), which appears to have occurred in response to a combination of raised soil inorganic N availability and stimulated litter inputs. Our data indicate that direct effects of N deposition on litter input and soil N availability significantly affected decomposition but indirect effects did not. We argue that indirect effects of changes to plant species composition could be stronger in natural ecosystems, which often contain a greater diversity of plant functional types than those considered here.  相似文献   
93.
Social capital, measured as the level of trustamong people, may be regarded as a newproduction factor alongside the traditionalones of human and physical capital. Withappropriate levels of social capital,monitoring and transaction costs can be savedand thus economic growth stimulated. Vialinking social capital to rural development andcomparing the cases of agricultural cooperativemovements in Denmark and Poland, this paperidentifies possible roots of building socialcapital and suggests that social capital wasbuilt through a lengthy process in bothcountries during the 19th century. However,the comparison of the present level of socialcapital indicates that the level of socialcapital is significantly higher in Denmark thanin Poland. The paper concludes that the reasonfor this difference is the fact that theoriginal accumulation of social capital inPoland was destroyed by the communist regime.  相似文献   
94.
Amaranthus hybridus and Amaranthus mantegazzianus are commonly cultivated and the entire young fresh plants consumed as vegetables in regions of Africa and Asia. A. hybridus and A. mantegazzianus were cultivated at four sites in three climate regions of the world: Santa Rosa, Argentina; Lleida, Spain; and Prague and Olomouc, both in the Czech Republic. The contents of flavonoids (isoquercitrin, rutin, nicotiflorin), hydroxybenzoic acids (protocatechuic acid, 4-hydroxybenzoic acid, vanillic acid), hydroxycinnamic acids (caffeic acid, p-coumaric acid, ferulic acid), hydroxycinnamyl amides (N-trans-feruloyltyramine, N-trans-feruloyl-4-O-methyldopamine), and betaines (glycinebetaine, trigonelline) were determined. The variation in phytochemical content due to species and cultivation site was analyzed utilizing the multivariate statistical methods of principal component analysis (PCA) and graphical model (GM). The Argentinean samples differed from the three other locations due to higher contents of most compounds. The samples from Spain and the Czech Republic differed from each other in the content of the negatively correlated metabolites trigonelline and the flavonoids. The two amaranth species were separated primarily by a higher content of trigonelline and the two hydroxycinnamyl amides in A. mantegazzianus. The GM showed that the quantities of the different analytes within each compound group were intercorrelated except in the case of the betaines. The betaines carried no information on each other that was not given through correlations with other compounds. The hydroxycinnamic acids were a key group of compounds in this analysis as they separated the other groups from each other (i.e., carried information on all of the other groups). This study showed the contents of polyphenols and betaines in the aerial parts of vegetable amaranth to be very dependent on growth conditions, but also revealed that some of the compounds (trigonelline and the two hydroxycinnamyl amides) may be useful as features of a taxonomic classification.  相似文献   
95.
1. A 525-bp fragment of a feather keratin (F-KER) gene was amplified. Four PCR products were sequenced. 2. Two substitutions in the amplified region were observed, one of them in the coding region of the gene (cysteine to glycine substitution in the protein). A new ACRS-PCR test for AvaI enzyme was designed. A total of 344 domestic pigeons (Columba livia var. domestica) were genotyped. 3. There were significant differences in the frequencies of alleles and genotypes between homing and non-homing pigeons. The frequency of the rare F-KER(G) allele was higher in the group of homing pigeons. 4. The effects of the detected polymorphism on flying performance should be verified in biomechanical studies.  相似文献   
96.
Infections with avian Metapneumovirus (aMPV) are often associated with swollen head syndrome in meat type chickens. Previous studies in turkeys have demonstrated that local humoral and cell-mediated immunity plays a role in aMPV-infection. Previous experimental and field observations indicated that the susceptibility of broilers and their immune reactions to aMPV may differ from turkeys. In the presented study local and systemic immune reactions of broilers were investigated after experimental infections with subtypes A and B aMPV of turkey origin. Both virus subtypes induced a mild respiratory disease. The recovery from respiratory signs correlated with the induction of local and systemic aMPV virus-neutralizing antibodies, which began to rise at 6 days post infection (dpi), when the peak of clinical signs was observed. In a different manner to the virus neutralizing (VN) and IgG-ELISA serum antibody titres, which showed high levels until the end of the experiments between 24 and 28 dpi, the specific IgA-ELISA and VN-antibody levels in tracheal washes decreased by 10 and 14 dpi, respectively, which may explain the recurring aMPV-infections in the field. Ex vivo cultured spleen cells from aMPV-infected broilers released at 3 and 6 dpi higher levels of IFN-γ after stimulation with Concanavalin A as compared to virus-free birds. In agreement with studies in turkeys, aMPV-infected broilers showed a clear CD4+ T cell accumulation in the Harderian gland (HG) at 6 dpi (P<0.05). In contrast to other investigations in turkeys aMPV-infected broilers showed an increase in the number of CD8alpha+ cells at 6 dpi compared to virus-free birds (P<0.05). The numbers of local B cells in the Harderian gland were not affected by the infection. Both aMPV A and B induced up-regulation of interferon (IFN)-γ mRNA-expression in the nasal turbinates, while in the Harderian gland only aMPV-A induced enhanced IFN-γ expression at 3 dpi. The differences in systemic and local T cell and possibly natural killer cell activity in the HG between turkeys and chickens may explain the differences in aMPV-pathogenesis between these two species.  相似文献   
97.
Immunization represents one of the most important methods to increase the resistance of chickens against Salmonella infection. In addition to the development of an adaptive immune response, oral administration of live Salmonella strains to day-old chicks provides protection against infection within hours by intestinal colonization-inhibition. For the exploitation of this phenomenon, practical information on colonization-inhibition between Salmonella organisms is needed. Colonization-inhibition capacity between Salmonella strains from serogroups B, C1, C2, D and G was assessed in chickens. The most profound level of intestinal colonization-inhibition occurred between isogenic strains. Inhibition between strains of the same serovar was greater than that between strains of different serovars. The degree of inhibition between different serovars was not sufficiently high to identify a single strain which might inhibit a wide range of other Salmonella organisms. However, as Salmonella Enteritidis is the dominant serovar in poultry in many countries and because of the profound colonization-inhibition within this serovar there is a considerable potential to exploit this phenomenon in the development of novel live S. Enteritidis vaccines. Treatment of young chicks with mixtures of different Salmonella serovars resulted not only in a very strong growth inhibition of the isogenic strains but also in a substantial inhibition of heterologous serovars. The potential of mixtures of heterologous Salmonella strains as a 'Salmonella Inhibition Culture' and as a 'live Salmonella vaccine' should be further explored.  相似文献   
98.
Spatial plans shape land-use changes, which in turn are main drivers of anthropogenic ecosystem alterations, therefore influencing the ecosystem services (ES) delivered by a given territory. However, integration of the ES concept in policies and plans is reported as poor in literature. The main goal of this research is to gain insight on the views and perceptions of Portuguese regional spatial planners regarding the ES concept and its integration in spatial plans. For that we designed and administered a questionnaire survey aimed at practitioners and decision-makers from Portuguese regional spatial planning authorities. The survey focused on issues such as the level of awareness and knowledge of the ES concept among planners, the perceived level of current ES integration in regional spatial plans and corresponding strategic environmental assessments, the main factors that either facilitate or obstruct that integration, or the level of importance given to ES integration in the planning process. Findings show that planners know the ES concept, they consider it as important to be integrated in spatial planning and, interestingly, that it is already rather integrated in existing plans. They believe that planning teams and authorities have skilled human resources for ES integration. However, they revealed a low knowledge on the main initiatives intended to push ecosystem services into the political agenda, like for example the Millennium Ecosystem Assessment. The questionnaire used can be easily transferred into other spatial planning contexts to draw, e.g. a broader European picture on ES integration in spatial planning.  相似文献   
99.
100.
Summary Potato food and non-food industries need information about dry matter (DM) and starch concentration of tubers. Therefore, calculation of dry matter concentration and starch concentration via under-water weight were optimised. Determination coefficients (R2) were 0.92 and 0.83 (starch concentration between 13 and 23%), and 0.94 and 0.88 (starch concentration ≥13%) for dry matter and starch concentration, respectively. In a second attempt, near infrared spectroscopy models for both constituents were calculated (R2 of validation set was 0.98 and 0.96 for dry matter and starch concentration, respectively). Results pointed out superiority of the near infrared technique with less divergence than the techniques of under-water weighting.  相似文献   
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