首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
The effect of level of removal of current season's shoots of heather (0,40 and 80% of the dry matter of the shoots) in the summer and autumn on the intake and diet selection by grazing Scottish Blackface wether sheep was examined in an experiment conducted over two years in which all combinations of level and season of grazing were provided. The treatment plots were grazed for 5 weeks at any one time and measurements made of intake and diet selection in weeks 2 and 5. In both the summer and autumn grazing periods level of removal in week 2 had little effect on the quality of the diet selected. In week 5, digestibility of organic matter was higher for the 40% than the 80% level of removal in the summer (0·543 vs 0·508) and particularly in the autumn (0·503 vs 0·449). Digestibility of the diet selected was higher in week 2 than in week 5 in both the summer (0·555 vs 0·525) and in the autumn (0·511 vs 0·476). Mechanisms of diet selection are discussed. In the summer grazing period only small differences existed in intake of organic matter between levels of removal but in the autumn intakes were higher at the 40% than the 80% level of removal. In a clipping experiment in which 0, 40 or 80% of the length of current season's shoots was removed in May, July and September in 3 consecutive years the nitrogen content of clippings in May and July was higher and the cell wall constituent lower at the 40% level in comparison to the 80% level of removal. Higher levels of removal at the previous clipping increased the nitrogen content of the clippings in May, July and September and reduced the cell wall constituent content in September.  相似文献   

2.
《Journal of Crop Improvement》2013,27(1-2):451-486
Abstract

This discussion summarizes current knowledge about rewards, risks, and reality surrounding the public's perception of genetically modified (GM) plants and foods. Differences in perception and acceptance of GM products between European and US publics are briefly described. The discussion includes recommendations for effective communication with the public. Pitfalls are identified that restrict credible discourse about the risks and benefits of GM ornamental plants and biotechnological products.

The U.S. gardening public is increasingly informed about technologies that influence their hobby interests, including plant biotechnology. Results of a preliminary and on-going survey of Tennessee Master Gardener Volunteers are presented that reveal consumer concerns similar to ones already voiced in the U.S. about GM foods. Discussion concludes by integrating these considerations, within the context of ongoing debate about GM foods, to provide implications about the success of novel GM ornamental plant introductions in the near future.  相似文献   

3.
Pea weevil (Bruchus pisorum L.) is one of the most serious insect pests of field pea (Pisum sativum L.) in Ethiopia. A survey of 400 farmers was conducted in four main pea-growing districts in north and north-western Ethiopia. The objectives were to assess farmers' knowledge and perceptions of pea weevil, to examine their current pest management practices and to identify challenges to pea weevil control, so that participatory integrated pest management for smallholder farmers in Ethiopia can be developed. The results revealed that most (71%) of the farmers surveyed had knowledge about pea weevil and were able to identify damaged seeds based on common visible symptoms of weevil infestation. However, most farmers did not know that pea weevil attacks plants in the field, but rather considered it a storage pest. The results also showed that farmers' cultural practices influence the incidence and spread of pea weevil and that most farmers did not check seed for pea weevil symptoms before planting. Only a minority of farmers (19%) harvested peas early and some harvested late, unintentionally promoting infestation and carryover of weevils. In addition, most farmers (74%) were not aware of the source and means of weevil spread on their farm and some did not clean up fallen and shattered peas during harvesting and threshing. The majority (63%) of the farmers surveyed relied on chemical insecticides, namely actellic dust and phostoxin, to treat harvested peas in storage. However, the results revealed a knowledge gap in that farmers were well aware of the problem of pea weevil, but lacked knowledge of cultural practices affecting pea weevil and of problems in the use of pesticides. This highlights the need for farmer training and for development of participatory integrated pest management methods for pea weevil.  相似文献   

4.
The Bahima ethnic group have been crossbreeding autochthonous Ankole with Holstein‐Friesian cattle. Separate herds (pure Ankole and crossbreds) are common. A survey was conducted to characterize pasture utilization and management in the Ankole region to gain a better understanding of current and emerging practices. Herds are largely grazed by continuous stocking although there are efforts to establish paddocks. Factors considered for pasture allocation to cattle genotypes were high‐quality feed, limited shrubs/weeds and close proximity to homestead for 80, 80 and 30% of farmers, respectively. Cross‐bred cattle were kept on medium/high‐quality, and Ankole cattle on medium/low‐quality pastures. Pastures for cross‐bred cattle yielded 0·17 t ha?1 more dry matter than pastures allocated to Ankole cattle. Crude protein (CP) content of Ankole pasture was significantly (P < 0·05) lower than CP of cross‐bred pasture (6·3% compared with 7·3%). Neutral detergent fibre content was similar (72·8% vs. 69·8%) for both pasture types. Farmers’ perceptions of indicator plant species were important for allocation of pasture. Hyparrhenia rufa, Brachiaria spp., Themeda triandra and Chloris gayana were identified as the preferred pasture species. Sporobolus pyramidalis and Cymbopogon afronardus were the most undesirable pasture species. Brachiaria spp. offers an opportunity for utilization as hay for dry season supplementation.  相似文献   

5.
Insect pests are a key constraint to effective utilization of cereal crops in sub-Saharan Africa (SSA), with damage caused by these pests in the stores of particular concern. Although a number of approaches have been advanced for control of storage pests of maize, uptake remains a challenge, with effectiveness of some approaches being questionable. We conducted a survey in western Kenya among 330 respondents using face to face interviews and focus group discussions to evaluate farmers' practices, knowledge and perceptions of storage pests of maize, and their current practices in managing such pests as a basis for development of efficient integrated pest management (IPM) approaches for the pests. Majority of the respondents stored maize in traditional granaries, with less than 10% of them using modern improved facilities, mainly due to inability to afford these. Majority of the respondents also cited attack of their stored grains by a number of insect pests, causing about 40% grain losses. The larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae), sawtoothed grain beetle, Oryzaephilus surinamensis (L) (Coleoptera: Silvanidae), and maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), were perceived as the most common and damaging pests. Farmers' perceptions of pests were positively and significantly influenced by level of education and farming experience, indicating that education and experience build farmers' understanding of storage pests. Storing maize in unshelled form seemed to result in less pest attack, although majority of the respondents stored their maize in shelled form. Moreover, local maize varieties were perceived to be resistant to pests. The farmers applied various control methods, with sun-drying being the most popular practice. Usage of pesticides was minimal, mainly due to high costs, lack of information, and unavailability of appropriate and effective products. There were also other cultural methods applied, such as use of smoke and insecticidal plants. The respondents decried lack of training and extension services on storage pests and their management, underscoring the need to develop extension services. The underlying mechanisms of the perceived pest resistance in local varieties of maize and cultural pest management methods need to be established for exploitation in development of effective IPM approaches. There is also need to address the challenges hindering uptake of modern storage and control approaches.  相似文献   

6.
Parkinson’s disease (PD) is the second most common neurodegenerative disease affecting people over age 55. Oxidative stress actively participates in the dopaminergic (DA) neuron degeneration of PD. Xyloketals are a series of natural compounds from marine mangrove fungus strain No. 2508 that have been reported to protect against neurotoxicity through their antioxidant properties. However, their protection versus 1-methyl-4-phenylpyridinium (MPP+)-induced neurotoxicity is only modest, and appropriate structural modifications are necessary to discover better candidates for treating PD. In this work, we designed and synthesized 39 novel xyloketal derivatives (1–39) in addition to the previously reported compound, xyloketal B. The neuroprotective activities of all 40 compounds were evaluated in vivo via respiratory burst assays and longevity-extending assays. During the zebrafish respiratory burst assay, compounds 1, 9, 23, 24, 36 and 39 strongly attenuated reactive oxygen species (ROS) generation at 50 μM. In the Caenorhabditis elegans longevity-extending assay, compounds 1, 8, 15, 16 and 36 significantly extended the survival rates (p < 0.005 vs. dimethyl sulfoxide (DMSO)). A total of 15 compounds were tested for the treatment of Parkinson’s disease using the MPP+-induced C. elegans model, and compounds 1 and 8 exhibited the highest activities (p < 0.005 vs. MPP+). In the MPP+-induced C57BL/6 mouse PD model, 40 mg/kg of 1 and 8 protected against MPP+-induced dopaminergic neurodegeneration and increased the number of DA neurons from 53% for the MPP+ group to 78% and 74%, respectively (p < 0.001 vs. MPP+ group). Thus, these derivatives are novel candidates for the treatment of PD.  相似文献   

7.
Results of a postal survey are presented, investigating perceptions among experts of possible future developments in UK plant-protection activities. The overall response rate to the survey was 70%.  相似文献   

8.
Glyphosate is world-wide seen as the most widely used herbicide ingredient. In Germany, from 1999 to 2010, the use of glyphosate based herbicides (GBH) increased by 100%. Many agronomical benefits are attributed to glyphosate, but there is also public criticism. To analyse current application patterns and to assess the agronomical importance of GBH in Germany, a survey was carried out among 896 arable farmers. The survey took place in early 2011, taking 2009 as a reference year. In Germany, cultivation of transgenic crops is generally not permitted and, therefore, herbicide resistance trait does not play any role in application patterns.Based on farmer's statements, a calculated application area of 4.3 million hectare arable land was estimated, representing 39% of total arable area. Three application modes receive major proportions of glyphosate use, these are: pre-sowing (20.7% of application area), pre-harvest (11.2%) and stubble application (68.1%). Among the field crops, oilseed rape (including oilseed rape stubbles) is treated with 27.5% of the nation-wide glyphosate amount followed by winter barley (20.1%) and winter wheat (15.8%). Without using glyphosate, farmers expect an increase in the share of ploughed arable land from 38.1% to 71.4%. Also, without glyphosate the use of cultivator on stubble land is expected to increase about 1.6 passes on average. If applied pre-sowing, glyphosate could save herbicide applications in the following crop. Saving one application of a post-emergence herbicide was estimated by farmers for corn and sugar beet (46% of pre-sowing applications), silage maize (40%), oilseed rape (27%), and winter wheat (22%). Most applications are applied on off-crop fields, so farmers did not quote any observation of yield savings due to glyphosate. The nation-wide economic benefit of glyphosate due to savings of other agricultural measures such as soil cultivation and post emergence herbicides is calculated between 79 and 202 million Euro per year, depending on glyphosate price.We conclude, that glyphosate offers large benefits to farmers, though some routine applications results in only moderate economic benefit compared to the non chemical practices being replaced. Developing decision rules for farmers might allow for an optimum allocation of glyphosate use.  相似文献   

9.
This study was carried out to investigate mechanical properties of naturally colored organic cotton (NaCOC) fabrics, to evaluate tactile sensory perceptions, and finally to identify the related mechanical parameters with the sensory perceptions. Two species, coyote-brown and green NaCOC fiber, commercially available, were selected and woven into plain and twill fabrics. Seventeen mechanical properties were measured by KES-FB system. Then, primary hand value (PHV) and total hand value (THV) were calculated by KN-203-LDY and KN-302-SUMMER, respectively. For sensory perception evaluation, 30 participants answered the questionnaire consisted of nine different bipolar adjectives dealing with tactile sensation using the semantic differential scale (SDS). As the result of mechanical properties, there were meaningful differences in shear, surface, compression properties, thickness, and weight of 4 NaCOC fabrics. For hand value, a coyotebrown twill fabric was evaluated as the most appropriate for lady’s summer dress applications. In sensory perception evaluation, meaningful differences of sensory perception were shown among 4 specimens except ‘fineness’ and ‘wetness’ perceptions. Prediction models for sensory perceptions of NaCOC fabrics were extracted by regression analysis in ‘softness’, ‘fineness’, ‘warmth’, ‘pliability’, ‘limpness’, ‘thinness’ and ‘wetness’ perceptions.  相似文献   

10.
In this study, polyethylene glycol (PEG) was used as an osmotic regulator in dough to investigate the effects of reduced NaCl content on dough properties. The effects of water content (±10% of Farinograph absorption) and PEG's molar mass on dough machinability (stickiness, work of adhesion and cohesiveness) were estimated using a full factorial design. PEG with different molar masses (400, ∼1600, and 3350 g/mol) was added at a concentration of 1 g/100 g flour. All properties measured were affected significantly by the variation of water content and PEG's molar mass. At lower levels of dough hydration, stickiness increased with an increase in PEG's molar mass, whereas the opposite trend was observed at higher levels of dough hydration, suggesting there may be an optimum between the water restriction effect induced by PEG and dough's physical properties. The interaction effect was significant for both stickiness and work of adhesion, showing interdependence between water content, PEG molecule size and dough physical properties. The effects of PEG's concentration and molar mass on dough machinability were also assessed by full factorial design. Increasing PEG's molar mass and concentration improved dough machinability, that is, dough with reduced stickiness was obtained.  相似文献   

11.
The hypocholesterolemic effect of a vegetable dietary protein was studied by comparing egg white protein and faba-bean protein concentrate in 4 hyperchol-esterolemic persons (3 type IIA, 1 type IIB) and 1 normal individual. To maintain stable body weight, participants were kept for 1 month on an isocaloric diet (20% protein, 48% CHO, 32% fat, P/S=2) and then hospitalized for two consecutive cross-over periods of 18 days each, when they again received an isocaloric diet but of different composition (15% protein, 59% CHO, 26% fat, P/S=2), with the two protein sources as the basis of the cross-over. Serum total, LDL-, VLDL- and HDL-cholesterol and total and VLDL-triglycerides were analyzed every three days. Compared to baseline values, serum total and LDL-cholesterol decreased during both diets, reaching statistical significance for the egg white diet; serum HDL-cholesterol significantly decreased on the faba-bean diet; serum total and VLDL-Tg did not show any significant changes. Comparisons of lipid values at the end of each diet (faba-bean vs. egg white) showed small differences in mean values, none statistically significant. In conclusion, evidence was not obtained that the faba-bean diet produced a significant lowering of serum total and LDL-cholesterol.  相似文献   

12.
《Field Crops Research》2006,95(2-3):327-335
Nepal has a wide diversity of rice landraces in all rice-growing areas from low to high altitude. A baseline survey in Jumla, a high-altitude site (2200–3000 m), identified rice landraces with different names that differed in phenotype and were adapted to the extreme high-altitude environment. Jumli Marshi was the most common traditional rice variety, accounting for 85% of samples collected. The genetic diversity of these landraces was assessed by agro-morphological variability and microsatellite marker polymorphism. Forty-two qualitative and quantitative traits and 39 microsatellite (simple sequence repeats, SSR) markers were assessed among accessions with 10 different names. The accessions showed low morphological diversity with an average Shannon Weaver diversity index of 0.23. Only 16 morphological traits showed significant variation among the accessions. Discriminant function analysis showed that only 36% of accessions could be clustered according to name by morphological traits. Only one SSR locus was polymorphic, distinguishing only one accession. The names used by farmers to describe the phenotypic characteristics of panicle and grains were inconsistent indicators of genetic identity. We conclude that the Jumla landrace population has a narrow genetic base. The diversity detected was sufficiently low for it to be possible that there was a single origin for all of the Jumla landraces.  相似文献   

13.
A total of 100 cultivated rice accessions,with a clear isozyme-based classification,were analyzed based on Cheng’s index and simple sequence repeat (SSR) marker.The results showed that the isozyme-based classification was in high accordance with that based on Cheng’s index and SSR markers.Mantel-test revealed that the Euclidean distance of Cheng’s index was significantly correlated with Nei’s unbiased genetic distance of SSR markers (r=0.466,P ≤ 0.01).According to the model-based group and cluster analysis,the Cheng’s index-and SSR-based classification coincided with each other,with the goodness of fit of 82.1% and 84.7% in indica,97.4% and 95.1% in japonica,respectively,showing higher accordance than that within subspecies.Therefore,Cheng’s index could be used to classify subspecies,while SSR marker could be more efficient to analyze the subgroups within subspecies.  相似文献   

14.
Surveys were undertaken in six districts of southwestern Ethiopia from July to October 2003 to investigate farmers’ perceptions and management practices of insect pests on traditionally stored sorghum. The survey involved 138 randomly selected farmers who were interviewed using a semi-structured questionnaire. Storage insect pests were perceived as the major insect pests of sorghum. The majority of the farmers estimated sorghum yield losses of up to 50% due to insect damage during storage. High temperature and lack of storage hygiene were cited as the major factors resulting in insect infestation of stored sorghum. Infestations of stored sorghum insect pests were common on different forms of sorghum, which stored in various types of farm storage. Farmers classified sorghum varieties according to the level of resistance to stored sorghum insect pests. Only about 32% of the farmers had access to chemical insecticides for the control of stored sorghum insect pests, while the majority of them used cultural practices and locally available plant materials as storage protectants.  相似文献   

15.
Summary A survey of control practices and grower perceptions of early blight in South Africa was conducted from May 2001 — July 2002 using an informally structured questionnaire. Questionnaires were collected from the 10 largest of the 14 potato production regions in South Africa. The predominant control method for early blight was the use of fungicides with mancozeb or chlorothalonil as active ingredient. Most respondents commence spraying at flowering and spray at 7–10 day intervals thereafter. BP1, Up-to-date and Mondial were the most commonly planted cultivars. The majority of farmers indicated that they would be willing to use an early blight decision support system if an accurate and cost-effective one was available, and that they believe more research is necessary on early blight in South Africa. Estimated economic losses ranged from 1–60%, with the average being approximately 20%. This is the first such survey to be conducted in South Africa.  相似文献   

16.
A survey of potato (Solanum tuberosum L.) plant stands in upstate New York over a three-year period showed that the average distance between plants was 4 cm wider than intended. Plant stands averaged 83%. The failure to plant seed pieces was the major reason for missing hills. Seed rot was not generally a problem, although one field in the survey was severely affected. Speed of planting up to 6.7 km/h had no consistent effect on average spacing or uniformity of seed piece distribution. Seed type (whole or cut) and mechanical condition of planter influenced spacing. Experiments conducted over four years indicated that the non-uniform seed piece distribution delivered by commercial picker-arm planters does not adversely affect crop yield or tuber size. Non-uniform seed distribution with extremely high coefficients of variation (greater than 100%), however, affected yield, tuber size and tuber number. Tuber numbers and yields were decreased by reducing the number of seed pieces planted per unit area whether or not the pieces were uniformly spaced.  相似文献   

17.
In this work, the total pentose (xylose and arabinose) and hydroxycinnamic acid (ferulic and p -coumaric acids) in eight lots of brewer's spent grain preserved by different methods (freeze-drying, oven drying and freezing) has been determined. The total acid-extractable pentose content of the samples varied between 13·0 and 19·5% dry weight for xylose, and 7·2 and 9·6% dry weight for arabinose, whereas the total alkali-extractable hydroxycinnamic acid content varied between 0·17 and 0·24% dry weight for ferulic acid, and between 0·068 and 0·121% dry weight for p -coumaric acid. Significant differences (p<0·05) between lots were found for ferulic and p -coumaric acids. With respect to the different preservation methods, significant differences (P<0·05) were only seen in arabinose content. The content of pentoses and hydroxycinnamic acids in brewer's spent grain has been compared with those from other agro-food residues whose use is also proposed for the enzymatic release of these compounds.  相似文献   

18.
Pressure performance and moisture management properties (MMP) of compression form-fitted athletic wear (CFA) play important role in achieving their mechanical functionality, wearing comfort, and physiological health for athletes during intensive exercises. Based on the 5Ps model, pressure and liquid moisture transfer attributes and their resultant subjective perceptions are analyzed and discussed through adopting objective and subjective measuring methods in this study. The MMP of eight types of fabric specimens were evaluated when the specimens were stretched at tension ratios of 0 %, 10 % and 20 % by applying an innovatively improved moisture management test method. Most of the tested specimens presented satisfied MMP when tested in a relaxed state. Testing under tension status significantly influenced the MMP of the tested specimens. The changes were mainly reflected in the prolonged wetting time, the increased absorption rates at the skin-contacted fabric surface, the reduced wetted radius and spreading speed at outer side of fabric, and the weakened one-way transfer properties. The tested fabrics with stretch of 20 % showed, in general, better performances in MMP than those with a stretch of 10 %. Pressure characteristic values ranging from 1679.88 to 2752.89 Pa on average were extracted from the different six pressure zones around the tested athletes’ bodies. Our improved MMT test method provides a new approach to study the fabric MMP when fabrics are under different tensions. Five sensory dimensions were used to analyze psychophysical responses to the physical stimulus of pressure and MMP, which revealed complex interactive mechanisms existing between pressure action, moisture transfer attributes and comfort perceptions related to compression athletic wear.  相似文献   

19.
Early blight, caused by the fungus Alternaria solani and brown leaf spot, caused by Alternaria alternata, are important diseases of potato crops in Idaho. In recent years growers have reported a reduction in efficacy of fungicides traditionally used in the past decade to control early blight. In 2009, a collection of A. solani 39 isolates were screened for resistance to azoxystrobin, pyraclostrobin, boscalid and famoxadone. Fungicide sensitivity testing was done using spiral plate dilution gradients. Results showed that of 39 isolates screened, all were resistant to azoxystrobin and three were resistant to boscalid. None were resistant to pyraclostrobin or famoxadone. In summer 2010, more isolates were collected (9 A. alternata and 26 A. solani) and the survey was expanded to include more fungicides with four different modes of action that targeted succinate dehydrogenase (SDH), methionine biosynthesis, mitochondrial respiration and multi-site contact activity. New isolates of A. solani and A. alternata were also collected from two additional sites. The results showed that 57% of the isolates were resistant to boscalid as well as an average of 63% of the isolates being resistant to the strobilurin fungicides. Seven and 15% of isolates were resistant to penthiopyrad (an SDH inhibitor), and pyrimethanil (a methionine biosynthesis inhibitor), respectively. However, none of the isolates were resistant to fluopyram (an SDH inhibitor) or a mixture of fluopyram and pyrimethanil. Although there appears to be cross resistance developing in Alternaria spp. to some of the new SDH inhibitors like penthiopyrad, others such as fluopyram are still showing limited to no resistance development in Alternaria spp. in Idaho.  相似文献   

20.
对进入实验室研究生新生开展了安全意识情况的问卷调查。通过问卷调查发现,研究生新生在实验室规章制度熟知程度、实验室安全意识及应急措施掌握、仪器设备规范操作、科研工作习惯养成等方面还存在一定的问题。针对这些问题,提出了切实发挥导师指导作用、定期开展实验室安全教育、加强仪器设备规范操作与维护管理、采用实验室门禁系统等措施,以利于研究生安全意识与技能的提高,促进实验室的良好运行与管理。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号