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51.
The occurrence of genetic erosion in local maize varieties in Mexico is intensely debated. Recent publications from Mexico show contradicting results about the loss of local varieties. Genetic erosion is a complex process, and well-documented examples of actual genetic erosion are not common in the literature. We worked in a region in which adoption of improved varieties was negligible, but other factors affecting maize agriculture were at play. The objectives of the study were to describe changes in maize diversity in the last 10 years and to associate them with socio-economic and environmental changes in a region in Mexico’s Central Highlands. We used richness and abundance of local varieties and diversity indices of races as indicators of maize diversity changes over time. We analyzed statistics and based on interviews we evaluated maize diversity changes between 2005 and 2015. We interviewed 113 farmers on two occasions with intervals from 5 to 10 years. According to climate statistics, rain has declined and temperature has increased. We also found a decrease in the lake level during the past 35 years. The total population in the region has doubled since the 1960s. The indigenous population has not changed significantly. Number of people working in agriculture has decreased since the 1960s. Rain fed agriculture decreased 8.1 % from 1990 to 2007. In four villages studied, farmed land area had decreased between 1995 and 2015. This reduction varies between 22 and 39 % depending on the village. Maize planted area decreased from 9675 to 8115 ha from 2003 to 2014. In the same period, avocado plantations grew from 34 to 786 ha. In despite of these changes, we did not find significant changes in average landraces per farmer (2.13 ± 0.28 in 2015) nor per village (4.15 ± 1.26 in 2015). Significant changes in maize races were not found either (1.91 ± 0.26 per farmer, 2.85 ± 0.86 per village in 2015). These results show that maize landrace diversity in the region is resilient but dynamic.  相似文献   
52.
The pig sector is struggling with negative attitudes of citizens. This may be the result of conflicting attitudes toward pig husbandry between citizens and other stakeholders. To obtain knowledge about these attitudes, the objectives of this study were (1) to determine and compare attitudes of various stakeholders toward animals, humans and the environment in the context of pig husbandry and (2) to determine and compare the acceptability of publically discussed issues related to pig husbandry of various stakeholders. A questionnaire was distributed to citizens, conventional pig farmers, organic pig farmers, pig husbandry advisors and pig veterinarians. Respondents could indicate their attitude toward aspects related to animals, humans and the environment in the context of pig husbandry and they could indicate their opinion about the acceptability of issues of pig husbandry, e.g. piglet mortality and inside pig housing. Based on measured attitudes and the acceptability of issues, the studied stakeholders could be divided into three distinctive groups. The group of citizens and organic pig farmers showed negative attitudes toward all aspects of pig husbandry, the group of conventional pig farmers and pig husbandry advisors only showed negative attitudes toward aspects related to economics and the group of pig veterinarians showed negative attitudes to specific aspects of pig husbandry. This indicates that stakeholders have different interests and different perspectives with regard to pig husbandry. The pig sector should learn to understand citizens’ perspectives and take these into account in their line of work, the implementation of animal welfare measures and in their communication.  相似文献   
53.
54.
Trustworthy eco-labels provide consumers with valuable information on environmentally friendly products and thus promote green consumerism. But what makes an eco-label trustworthy and what can government do to increase consumer confidence? The scant existing literature indicates that low governmental involvement increases confidence. This suggests that government should just provide the basic legal framework for eco-labeling and leave the rest to non-governmental organizations. However, the empirical underpinning of this conclusion is insufficient. This paper analyses consumer confidence in different organic food labeling regimes with varying degrees of governmental involvement. Using unique and detailed survey data from the US, United Kingdom, Denmark, and Sweden, the analysis shows that confidence is highest in countries with substantial state involvement. This suggests that governments can increase green consumerism through active and substantial involvement in eco-labeling.  相似文献   
55.
Winter hardiness is a major-limiting factor for St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] grown in the transitional climatic region of the United States. Lab-based freeze tests that mimic the range of field winter survivability in St. Augustinegrass can contribute to the selection of cold hardy genotypes. This study used a whole container method, four freezing temperatures, and two data collection systems to evaluate the freezing response of nine St. Augustinegrass genotypes ranging in their winter hardiness. Results indicated ?3 and ?4 °C with average regrowth ratings of 33.6 and 17.8% respectively, were more suitable temperatures for evaluating freeze survival in St. Augustinegrass than ?5 and ?6 °C with average regrowth ratings of 0.4 and 0%, respectively. Visual ratings of surviving green tissue and regrowth were generally well correlated when evaluated over a six week period post-freeze with Pearson correlation coefficients ranging of 0.17–0.62  for ?3 °C freeze tests and 0.79–0.93 for ?4 °C freeze tests. Additionally, measurement of percent green cover using digital imaging techniques commonly utilized in turfgrass field studies were significantly correlated (0.66) with visual ratings averaged across weekly post-freeze evaluation measurements for both ?3 and ?4 °C freezing temperatures. These results provide evidence that digital imaging analyses are useful in estimating surviving green tissue and regrowth in lab-based freeze tests. This study provides additional information regarding freezing temperatures, genotype responses, and data collection methods in St. Augustinegrass, which should aid breeders in the improvement of freeze tolerance in the species.  相似文献   
56.
Twenty-eight Egyptian cotton (Gossypium barbadense L.) genotypes (varieties and hybrids) were used for analysis of genetic diversity using DNA based markers (ISSR, SSR, and EST) and to study varietal development of cotton. The ISSR markers gave the highest percentage of polymorphic bands as well as polymorphic information content compared with the other molecular markers (i.e. EST and SSR markers). Using clustering analysis, no general clustering according to the pedigree history of the genotypes was observed. Using principal coordinate analysis (PCOORDA), cotton genotypes were separated by the first three principal coordinates (PC1, PC2, and PC3) accounting for 11.5, 8.6, and 7.2% of the total genetic variance, respectively. The cotton genotypes were distributed into three parts based on the first PC, each part containing a group of varieties having a common ancestor. ‘Giza 12’ variety was the common ancestor for the varieties included in the first part and ‘Ashmouni’ variety was the common ancestor for the varieties included in the second part, while both ‘Sakha 3’ and ‘Sakha 4’ varieties were common ancestors for the varieties included in the third part. The results of the PCOORDA also showed better resolution of the genetic diversity than cluster analysis especially in the illustration of the varietal development of cotton. That means that principal coordinate analysis can be strongly used either alone or in combination with cluster analysis to discuss both genetic diversity and varietal development in the cotton genotypes.  相似文献   
57.
The uniform and precise application of microbial particles close to the target organism and to the plant to be protected can increase the success of a biological control treatment. The use of systems or technologies which are usually available in agriculture could influence the acceptability of biocontrol agents by farmers, and enlarge the market. A pilot system was realized using dripper lines, drippers, filters and other tools commonly used in irrigation and precision agriculture in the greenhouse to evaluate their suitability for applying and distributing microbial biocontrol agents. Conidial suspensions of marketed or marketable agents were used, i.e. Fusarium oxysporum, F. solani, Trichoderma harzianum and Paecilomyces lilacinus. The experiments carried out demonstrated that conidial suspensions (106 conidia ml−1) can pass through the drippers without causing clogging, regardless of their size, and remained viable. The term ‘microbigation’ is here proposed for this kind of microbial application technique.  相似文献   
58.
In March of 2012, following a robust activist campaign, Arysta LifeScience withdrew the soil fumigant methyl iodide from the US market, just a little over a year after it had finally been registered for use in California. As a major part of the campaign against registration of the chemical, over 53,000 people, ostensibly acting as citizens rather than consumers, wrote public comments contesting the use of the chemical for its high toxicity. Although these comments had marginal impact on the outcome of the case, these comments are of interest for what they say about public action at a time when efforts to address food and agricultural issues have been dominated by “voting with your fork.” Based on a qualitative textual analysis of approximately 3500 representative comments made available to us, we show that many of those taking action did not abandon consumer subjectivities associated with neoliberal governmentality. By threatening “personal boycotts,” some were acting in their capacity as individual consumers; in invoking their own and their children’s health many more were also acting on behalf of consumers, despite that the chemical in question is applied before strawberries are planted and thus leaves no residues. The emphasis that letter writers gave to their own bodies reinforces the idea that some bodies count more than others and thus reveals a biopolitical sorting. Having consumer lives matter is consequential in light of evidence that consumer concern about pesticides has historically led to formulations and regulations more protective of consumers than workers and neighbors.  相似文献   
59.
Managing the Essential Zeros in Quantitative Fatty Acid Signature Analysis   总被引:1,自引:0,他引:1  
Quantitative fatty acid signature analysis (QFASA) is a recent diet estimation method that depends on statistical techniques. QFASA has been used successfully to estimate the diet of predators such as seals and seabirds. Given the potential species in the predator’s diet, QFASA uses statistical methods to obtain point estimates of the proportion of each species in the diet. In this paper, inference for a population of predators is considered.  相似文献   
60.
Phosphorus (P) immobilization in soil involves geochemical (e.g., sorption, precipitation, and diffusion) and microbiological (microbial uptake) processes. Using a Brazilian Ultisol, relative contributions of both processes to the total immobilization of applied P over 14 days were investigated. The P immobilized by microbes as interpreted by microbial suppression (achieved by mercury sterilization) was 17, 50, 54, and 56% (of the total immobilized P) on days 3, 7, 10, and 14 after fertilization, respectively. In the short-term (1 to 3 days), microbes played less of a role than did the physical effect of shaking the soil, but became the major factor by days 7 to 14. Geochemical process that might be considered short-term ageing caused only 13–16% of the total immobilization in the same time period above. Calculations supported the interpretation that measurable diffusion occurred across water films on the soil particles.  相似文献   
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