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61.
Field trials testing a total of 27 clones of the interspecific hybrid Acacia mangium × A. auriculiformis and seedling controls of the parental species were established at Ba Vi and Yen Thanh in the north of Vietnam and Long Thanh in the south. At both Ba Vi and Yen Thanh there were significant (P < 0.001) differences in height and diameter at breast height (DBH) among 22 tested clones at 4 years. At Long Thanh, twelve hybrid clones did not differ significantly in DBH at age 3 years, but did (P < 0.001) at age 5 years. At the two northern sites the acacia hybrid clones had significantly greater DBH than control seedlots of the parental species. At Long Thanh, DBH of the hybrid clones and A. mangium was similar, with a genetically improved seedlot of A. mangium displaying the best DBH. Mean wood basic density at breast height of the acacia hybrid clones was 539 kg m−3 at Yen Thanh at age 8 years, and 473 kg m−3 at Long Thanh at age 5 years; density for A. mangium at Long Thanh was only slightly lower than the hybrid clones at 461 kg m−3. Linear regressions of Pilodyn penetration (PP) at breast height on wood basic density explained 60% of the variance in density of treatments (clones and control seedlots) at Yen Thanh and 36% at Long Thanh. There were significant differences between hybrid clones in PP at all three trial sites. Clonal DBH performance was not strongly correlated across the three trial sites; Pearson correlations of clone mean DBH between pairs of sites ranged from −0.47 to 0.20. Clonal rankings for PP were more stable, with Pearson correlations between pairs of sites ranging from r = 0.71 to 0.78.  相似文献   
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63.
Basal hexapodan orders (Apterygota) are traditionally divided in two well defined taxonomic groups, Entognatha and Ectognatha. Entognathy (the enclosed mouthparts condition) is considered the most distinctive character joining the Ellipura (Protura+ Collembola) with the order Diplura, whereas the presence of exposed mouthparts (ectognathy) is the feature shared by Microcoryphia and Zygentoma with the pterygote insects. In spite of the growing interest for the evolutionary history of the Apterygota, there is no complete agreement among the general phylogenetic hypotheses based on the study of morphological characters. In this study we analyzed the DNA sequence of segments of the nuclear Elongation Factor-1α(EF-1α) and of the mitochondrial 12S rRNA genes, and used different methods of phylogenetic reconstruction. The 12S gene seems to be more suited than the EF-1α to resolve some of the most outstanding systematic disputes, whereas the lack of resolution at the deeper nodes does not allow to assess the phylogenetic relationships within Microcoryphia and between ectognathan orders. We have obtained a fairly high support for the monophyly of the orders Diplura and Zygentoma. In the 12S analysis, the Ellipura and the Entognatha form monophyletic assemblages. In addition, the study of the distribution of introns in the EF-1α suggests a relationship between Collembola and Diplura.  相似文献   
64.
Lack of systematic evaluation of the effectiveness of conservation practices has hindered advances in scientific management of biodiversity. Development of an evidence-based framework of the kind used in the health services has been advocated as an approach to address this problem. Here we report on and evaluate the first two ecological systematic reviews undertaken using this framework. The subjects were the effectiveness of burning as a conservation intervention for UK sub-montane, dry dwarf shrub heaths (heath review) and blanket bog (bog review). Systematic search yielded 13 data sets from seven ‘heath’ articles and 11 data sets from eight ‘bog’ articles. Data from the heath review were of sufficient quality to enable meta-analysis whereas data from the bog review was synthesised by “vote counting”. Meta-analysis of the heath data indicates that floristic diversity is variable, particularly in early post-fire successional sequences, but older stands experienced significantly greater loss of diversity than younger stands. The bog review indicates that there are no consistent changes in floristic composition in response to burning. The evidence-base for upland management by burning is insufficient to generate robust management recommendations highlighting the necessity for further work. Feedback from the dissemination of the reviews provided valuable lessons for future reviews in terms of stakeholder involvement in question formulation and the balance between a reductionist and holistic approach. Systematic reviews are appropriate tools for conservation management and formalise the information available based on the weight of evidence. Evidence will commonly be lacking in many areas of conservation biology and the evidence-based framework effectively exposes this situation in a way that can determine requirements for needs-led research.  相似文献   
65.
An important environmental and regulatory issue is the protection of human health from potential adverse effects of cumulative exposure to multiple chemicals. Earlier literature suggested restricting inference to specific fixed-ratio rays of interest. Based on appropriate definitions of additivity, single chemical data are used to predict the relationship among the chemicals under the zero-interaction case. Parametric comparisons between the additivity model and the model fit along the fixed-ratio ray(s) are used to detect departure from additivity. Collection of data along reduced fixed-ratio rays, where subsets of chemicals of interest are removed from the mixture and the remaining compounds are at the same relative ratios as considered in the full ray, allow researchers to make inference about the effect of the removed chemicals. Methods for fitting simultaneous confidence bands about the difference between the best fitting model and the model predicted under additivity are developed to identify regions along the rays where significant interactions occur. This general approach is termed the “single chemicals required” (SCR) method of analysis. A second approach, termed “single chemicals not required” (SCNR) method of analysis, is based on underlying assumptions about the parameterization of the response surface. Under general assumptions, polynomial terms for models fit along fixed-ratio rays are associated with interaction terms. Consideration is given to the case where only data along the mixture rays are available. Tests of hypotheses, which consider interactions due to subsets of chemicals, are also developed.  相似文献   
66.
Soil management influences food production, economic performance of farm businesses, and a range of public benefits such as water quality, flood control and aquatic and terrestrial biodiversity. The aim of this paper is to explore the role of participatory research in combining scientific and farmer knowledge of soils to meet these multiple objectives. We use five separate research studies involving communication, consultation and co‐production, carried out in the English East Midlands between 2014 and 2018. We compare the participatory processes for knowledge exchange and their material outcomes and assess them retrospectively against specified criteria for successful application of participatory research. We conclude that, depending on context and scalar fit, multiple approaches to participatory research can be complementary, strengthen engagement and build trust within a farming community, resulting in a greater shared understanding of how to address the soil management objectives of farmers and wider society.  相似文献   
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68.
In the past five decades, constant research has been directed towards yield improvement in pigeonpea resulting in the deployment of several commercially acceptable cultivars in India. Though, the genesis of hybrid technology, the biggest breakthrough, enigma of stagnant productivity still remains unsolved. To sort this productivity disparity, genomic research along with conventional breeding was successfully initiated at ICRISAT. It endowed ample genomic resource providing insight in the pigeonpea genome combating production constraints in a precise and speedy manner. The availability of the draft genome sequence with a large‐scale marker resource, oriented the research towards trait mapping for flowering time, determinacy, fertility restoration, yield attributing traits and photo‐insensitivity. Defined core and mini‐core collection, still eased the pigeonpea breeding being accessible for existing genetic diversity and developing stress resistance. Modern genomic tools like next‐generation sequencing, genome‐wide selection helping in the appraisal of selection efficiency is leading towards next‐generation breeding, an awaited milestone in pigeonpea genetic enhancement. This paper emphasizes the ongoing genetic improvement in pigeonpea with an amalgam of conventional breeding as well as genomic research.  相似文献   
69.
OBJECTIVE: Several environmental factors influence adolescents' food habits and television (TV) viewing is thought to be one of these factors. The purpose of the present study was to describe sociodemographic differences in TV viewing and to examine associations of TV viewing with the consumption of sweets, soft drinks, fruit and vegetables in different countries. METHODS: Data were collected from 162,305 young people completing the 2001/02 Health Behaviour in School-Aged Children survey, a World Health Organization cross-national study on health and health behaviours among 11-, 13- and 15-year-old school pupils. Analyses of variance were used to examine sociodemographic differences in TV viewing and logistic regression analyses to examine associations between TV viewing and food habits. RESULTS: Large differences were found between countries in reported daily TV viewing time, from an average of 2.0 h in Switzerland to 3.7 h in Ukraine. The results indicate that those most likely to watch TV are boys, 13-year-olds and pupils of lower socio-economic status. Those who watched more TV were more likely to consume sweets and soft drinks on a daily basis and less likely to consume fruit and vegetables daily, although the latter associations were not so apparent among Central and Eastern European countries. CONCLUSIONS: Given the high TV viewing rates among adolescents and the association with less healthy food options, many young people are at increased risk of overweight or obesity. Interventions to modify TV viewing behaviour are needed. The findings underscore the importance of tackling socio-economic differences.  相似文献   
70.
  • ? The aim of this study was to investigate the effectiveness of using cellulose content, measured by the diglyme-HCl method, as a selection trait in breeding programs for kraft pulp yield in Eucalyptus urophylla.
  • ? A total of 275 trees from sixty-two families were sampled from a thinned progeny trial of E. urophylla in northern Vietnam to evaluate cellulose content from breast-height increment cores. Among those, twenty unrelated trees were felled to evaluate cellulose content and pulp yield from breast-height disk samples.
  • ? The regression of pulp yield of disk samples on cellulose content was strong either from disks (R 2 = 0.83) or increment cores (R 2 = 0.69). There was no significant difference in cellulose content between the provenances. The narrow-sense within-provenance heritability of cellulose content was 0.50 and the coefficient of additive genetic variation was 3.9%. Genetic correlations between cellulose content and growth (0.28–0.45) or wood basic density (?0.02) were not significantly different from zero.
  • ? Breast-height increment core cellulose content measured by diglyme-HCl method is under strong genetic control and can be used to rank trees for pulp yield in E. urophylla plantations. Selection for increased cellulose content would have only minor effects on growth and wood basic density.
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