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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Bird damage to vegetable crops in Long Valley during winter

Hui, Wun-fung, 許桓峰 January 2013 (has links)
Long Valley is the largest agricultural wetland in Hong Kong and supports a high level of biodiversity. The implementation of Management Agreement project in Long Valley has successfully enhanced its conservation value through habitat management and various eco-agricultural practices. However, the conflict between profitable agricultural yield and bird conservation in the area has also been intensifying as reflected by the increasing number of complaints of bird-related crop damage from local farmers in winter. The study aimed to assess the extent and impact of crop damage caused by birds in Long Valley during winter. The first part of the study involved a transect survey in the area reported to be the most severely affected area of Long Valley to determine the bird diversity and abundance, also the environmental factors of individual farmland plots were collected for analysis of their relationship with bird distribution. The bird species responsible for crop damage (targeted species) were also identified. The second part of the study evaluated the impact of different targeted species by using the technique of focal animal sampling, which involved focused observation of individual bird’s behaviour in the field and to quantify its time budget spent on crop-damaging behaviour. In order to understand the perspectives from farmers, face-to-face interviews with farmers practicing in the area were also conducted. The study identified five species to have crop-damaging behaviour, which can be further divided into two groups: the crop-consuming species causing actual crop damage included Chinese Bulbul (Pycnonotus sinensis), Crested Myna (Acridotheres cristatellus) and Eurasian Tree Sparrow(Passer montanus). The incidental crop-pecking species causing minimal crop damage included the White Wagtail (Motacilla alba)and Yellow Wagtail (Motacilla tschutschensis). Lettuce (Lactuca sativa) was the only type of crop suffering from bird damage. The intensity of crop-damaging behaviour of a species was estimated by the mean time allocated in crop consumption, and was found to be 66.7%±7.3% in Chinese Bulbul, 31.6%±29.1% in Eurasian Tree Sparrow and 8.9%±12.0% in Crested Myna. However, taking into account of the abundance, distribution and activity record of a species, Crested Myna showed the greatest overall impact to the vegetable crops. Chinese Bulbul showed a relatively focal but intensive damage to a few plots. It was found that having wires and a wet field nearby the plots were significant determinants of the presence of Eurasian Tree Sparrow. And the presence of Chinese Bulbul was significantly associated with the use of bird deterrents. Crested Myna was found in significantly higher numbers in late afternoon and was associated with plots having the seedling stage of lettuce growth. The study shows that birds do cause localized and patchy damage to vegetable crops in Long Valley. Individual farmlands may exhibit variations in severity of the damage due to the difference in species distribution and environmental factors. The management of bird damage must therefore be individualized from plot to plot. Also education and engagement with local farmers are indispensable to maintaining sustainable agricultural development while conserving avifauna in Long Valley. / published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management
2

Paddy crop loss and farmers' response to crop loss compensation in west Malaysia

Tan, Siew Hoey. January 1983 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1983. / Typescript. Vita. Description based on print version record. Includes bibliographical references (leaves 244-249).
3

Assessment of crop losses from ozone using biomonitor plants and risk estimates by experts

Brown, Gordon Lindal January 1990 (has links)
Environmental policy makers are required to make decisions under uncertainty regarding the benefits and costs of specific regulatory action. Uncertainty is a phenomenon that cannot be avoided in the assessment of environmental impacts, due to the inherent stochasticity of environmental systems, as well as a lack of adequate empirical data related to specific cause and effect relationships. A primary constraint associated with generation of adequate data from experiments is that environmental research is expensive, and conclusive results may take several years to obtain. In the meantime, significant impacts could be occurring, virtually undetected. A high degree of uncertainty exists in the assessment of the potential effects of ozone (O₃) pollution on agricultural crop yield. Thus, the purpose of this research was to provide information related to the potential impacts of O₃ pollution on crops in the Fraser Valley east of Vancouver, British Columbia, Canada. Two alternate methods were utilized: (i) biomonitoring with Bel W-3 tobacco, a plant variety that is very sensitive to O₃, and (ii) expert judgments of the risks of crop losses from O₃. The biomonitor survey was conducted over three growing seasons (1985 - 1987), in which ambient O₃ pollution conditions were atypically low, limiting the injury response data obtained. However, a correlation was established between biomonitor injury response and ambient O₃ levels, demonstrating that phytotoxic pollution conditions occurred during these years. Calibration of biomonitor injury response with crop yield losses revealed the following: (i) yield losses due to O₃ exposure are likely in the event that biomonitor plants exhibit O₃-induced injury symptoms, and (ii) the absence of biomonitor injury does not preclude the possibility of crop loss, since the O₃ exposure threshold for biomonitor injury may exceed that for loss of certain crops. Although experts are commonly used to provide judgments of potential impacts under uncertainty, there is a paucity of information regarding the desirable attributes of expertise. Selection of experts is largely an ambiguous task, and choices of experts by different persons are likely to be inconsistent. Prior to selection of experts for this project, a comprehensive survey was conducted of over 200 environmental professionals to determine the characteristics of an expert in O₃ effects on crops. It was shown that expertise in this area involves a considerable number of attributes. These were grouped, using factor analysis, into seven independent dimensions: education, type of career experience, length of career experience, cognitive skills, personal qualities related to credibility, scientific recognition and involvement in the scientific community. In general, there was agreement between different groups (e.g., research scientists and members of conservation groups) regarding the relative importance of the various dimensions of expertise. Nine crop loss experts were selected, based on nomination by a large group (166) of their scientific peers. It was demonstrated with regression analysis that nominated experts exhibited the attributes identified in the survey. Logit models were estimated that predict an individual's degree of expertise in O₃ effects on crops, based on specific attributes possessed by that individual. Independent judgments were then obtained from the nine experts regarding probable crop losses under typical O₃ pollution conditions in the Fraser Valley. Probabilistic judgments of crop losses were generally similar among experts and approximated the level of crop losses predicted from the biomonitor survey. Limited empirical exposure-response information for Fraser Valley crops indicated that some cultivars may be more sensitive than assumed by the experts. Additional exposure-response experiments will be required to determine the source of this inconsistency. / Science, Faculty of / Resources, Environment and Sustainability (IRES), Institute for / Graduate
4

An investigation of the accuracy of two postharvest grain loss assessment methods

Graham, Steven M. January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
5

The effect of wheat soilborne mosaic virus on agronomic characters of wheat

Nykaza, Scott M. January 1978 (has links)
Call number: LD2668 .T4 1978 N94 / Master of Science
6

The management of browsing damage caused by wallabies in Australian plantations

Montague, Thomas L. January 1993 (has links)
No description available.
7

Aphids and thrips : the dynamics and bio-economics of cereal pests /

Larsson, Hans, January 2005 (has links) (PDF)
Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniv. / Härtill 5 uppsatser.
8

An assessment of perceived crop damage in a Tanzanian village impacted by human-elephant conflict and an investigation of deterrent properties of African elephant (Loxodonta africana) exudates using bioassays

Karimi, Rebekah R. Schulte, Bruce A. January 2009 (has links) (PDF)
"A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science." Title from PDF of title page (Georgia Southern University, viewed on June 19, 2010). Bruce A. Schulte, major professor; Lissa M. Leege, J. Michelle Cawthorn, committee members. Electronic version approved: December 2009. Includes bibliographical references (p.76-78).
9

Postharvest losses and changes in quality of vegetables from retail to consumer : a case study of tomato, cabbage and carrot

Munhuewyi, Karen 12 1900 (has links)
Thesis (MScFoodSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Postharvest losses of three different vegetables (tomato - a fruit, cabbage - a leaf and carrot - a root vegetable) were investigated directly after retail purchasing and during consumer simulated storage. To conduct this study, three retail outlets (2 supermarkets and an outdoor market) were selected in Stellenbosch, South Africa. Retail prices of each vegetable were recorded from each respective Outlet. Surrounding environmental conditions (air temperature and relative humidity) at retail and during simulated consumer storage were also monitored. Vegetable postharvest losses were determined by quantifying the incidence of physical loss and changes in physico-chemical properties (colour, firmness, weight loss, ascorbic acid, total pigments, total soluble solids, titratable acid and proximate composition) over time. The percentage losses observed were then used to estimate the associated economic and environmental resource impacts of postharvest vegetable losses at the national level. Vegetable losses immediately at retail purchase were 14.56%, 21.21% and 17.93% for tomato, cabbage and carrot, respectively. The estimated combined volume lost for all three vegetables at national level was approximately 26 460 t valued at R33.70 million. Overall economic loss was highest for tomatoes and least for carrots. The magnitude of the losses observed differed for all the outlets. Vegetable losses were mostly high for the produce from the outdoor market compared to the supermarkets during storage. Throughout the whole trial, mechanical damage accounted for at least 50 to 70% of the losses while the remainder was due to decay and insect damage. Post retail storage temperature; ambient (22–25ºC) vs. cold store (0ºC and 10–12 ºC) had a significant (P<0.05) effect on the vegetable losses. This was for both quantitative and qualitative attributes. Losses for tomato and cabbage were 18.52% and 16.67% after 3 days while carrot losses were 11.83% at 7 days after having been kept in the recommended respective cold storage temperatures. Ambient storage losses were also lowest for carrots at 22.53% after 7 days, while tomato and cabbage losses stood at 24.27% and 34.34% after 3 days of storage, respectively. Vegetable firmness generally decreased while weight loss increased with storage time. Colour development increased favourably at ambient temperature for the tomato whereas for cabbage and carrot better colour retention was observed in the cold storage. Chemical changes for all three vegetables were also most pronounced at ambient temperature with significant (P<0.05) losses observed for ascorbic acid. Changes were also noted for total pigments, soluble solids and acidity, however there was no common significant trend for all three vegetables. Estimates of carbon dioxide emissions reveal that postharvest vegetable losses contribute to unwarranted emissions of at least 1.37 – 13.77 million tonnes of carbon dioxide equivalents (CO2eq.) at the national level. The losses are also accompanied by wastage of approximately 3.74 – 4.35 million m3 of fresh water as well as 14.79 – 111.63 million MJ of fossil energy. The vegetable with highest production volumes and retail price was the tomato and accordingly, its postharvest losses had the severest environmental and resource impacts. / AFRIKAANSE OPSOMMING: Die ná-oes-verliese van drie verskillende groentes (tamatie – 'n vrug, kool – 'n blaar, en wortel – 'n wortelgroente) is direk ná kleinhandelaankope en tydens gesimuleerde verbruikersberging ondersoek. Ten einde hierdie studie uit te voer, is drie kleinhandelsafsetpunte (twee supermarkte en 'n opelugmark) in Stellenbosch, Suid-Afrika gekies. Die kleinhandelpryse van elke groente van die drie onderskeie afsetpunte is opgeteken. Omliggende omgewingstoestande (lugtemperatuur en relatiewe humiditeit) tydens verkope en gesimuleerde verbruikersberging is ook gemonitor. Die ná-oes-verliese van die groentes is bepaal deur die voorkoms van fisiese verlies en veranderings in fisio-chemiese eienskappe (kleur, fermheid, gewigsverlies, askorbiensuur, totale pigmente, totale oplosbare suikers, titreerbare suur en algemene samestelling) met verloop van tyd te versyfer. Die waargenome persentasie verliese is gebruik om die geassosieerde ekonomiese en omgewingshulpbron-impak van ná-oes-groenteverliese op nasionale vlak te beraam. Groenteverliese met kleinhandelaankope was onderskeidelik 14.56%, 21.21% en 17.93% vir tamaties, kool en wortels. Die beraamde saamgestelde volume verlies vir al drie groentes op nasionale vlak was ongeveer 26 460 t, met 'n waarde van R33.70 miljoen. Die algehele ekonomiese verlies was die hoogste vir tamaties en die laagste vir wortels. Die omvang van die waargenome verliese het vir al die afsetpunte verskil. Groenteverliese tydens berging was hoofsaaklik hoog vir die produkte van die opelugmark in vergelyking met dié van die supermark. Tydens die algehele proefneming was meganiese skade verantwoordelik vir ten minste 50 tot 70% van die verliese, terwyl die res aan verrotting en insekskade toegeskryf kan word. Bergingstemperatuur ná kleinhandelaankope: omgewingstemperatuur (22 – 25 ºC) vs. koue berging (0 ºC en 10–12 ºC) het 'n beduidende (P < 0.05) uitwerking op groenteverlies gehad. Dit geld vir sowel kwantitatiewe as kwalitatiewe attribute. Verliese vir tamaties en kool was onderskeidelik 18.52% en 16.67% ná drie dae, terwyl dit vir wortels 11.83% teen sewe dae was nadat dit teen die aanbevole onderskeie koue bergingstemperature geberg is. Bergingsverliese in omgewingstemperatuur was ook die laagste vir wortels teen 22.53% ná sewe dae, terwyl die verlies van tamaties en kool onderskeidelik 24.27% en 34.34% was ná drie dae se berging. Die fermheid van die groente het oor die algemeen met die duur van berging verminder, terwyl gewigsverlies toegeneem het. Kleurontwikkeling het gunstig teen omgewingstemperatuur toegeneem vir die tamaties, terwyl die kleur van kool en wortels beter in die koue berging behou is. Chemiese veranderinge vir al drie groente was die sterkste teen omgewingstemperatuur, met beduidende (P < 0.05) verliese van askorbiensuur wat waargeneem is. Veranderinge is ook gemerk rakende totale pigmente, oplosbare vaste stowwe en suurgehalte. Daar was egter geen algemene beduidende neiging vir al drie groentes nie. Beramings van koolstofvrystellings toon dat ná-oes-groenteverlies tot ongeoorloofde vrystelling van ten minste 1.37 tot 13.77 miljoen ton koolstofekwivalente (CO2eq.) op nasionale vlak bydra. Die verliese gaan ook gepaard met verbruik van ongeveer 3.74 tot 4.35 miljoen m3 vars water asook 14.79 tot 111.63 miljoen MJ fossielbrandstof. Die groente met die hoogste produksievolume en kleinhandelprys was die tamaties, en gevolglik het tamaties se ná-oes-verliese die ernstigste impak op die omgewing en op hulpbronne.
10

Recolhimento mecanizado do café em função do manejo do solo e da declividade do terreno / Mechanized coffee gathering in function of the soil management and land declivity

Tavares, Tiago de Oliveira [UNESP] 29 February 2016 (has links)
Submitted by TIAGO DE OLIVEIRA TAVARES null (tiagoolitavares@hotmail.com) on 2016-03-31T00:01:52Z No. of bitstreams: 1 Dissertação_Tiago_de_Oliveira_Tavares.pdf: 1978145 bytes, checksum: ce74e5f5723fa0727dc1201f786f6631 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-04-01T14:27:43Z (GMT) No. of bitstreams: 1 tavares_to_me_jabo.pdf: 1978145 bytes, checksum: ce74e5f5723fa0727dc1201f786f6631 (MD5) / Made available in DSpace on 2016-04-01T14:27:43Z (GMT). No. of bitstreams: 1 tavares_to_me_jabo.pdf: 1978145 bytes, checksum: ce74e5f5723fa0727dc1201f786f6631 (MD5) Previous issue date: 2016-02-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A colheita do café de varrição é uma prática essencial na cafeicultura nos dias de hoje, pois o café caído de forma natural somado ao caído pela operação da colhedora fazem com que até 25% da produção esteja no solo, valor este dependendente de vários fatores relacionados à planta e às colhedoras utilizadas. Nos últimos anos, a mecanização deste processo se tornou comum, principalmente devido à oneração e à indisponibilidade de mão de obra. Porém, os poucos estudos existentes com estas máquinas dificultam as tomadas de decisões quanto às suas regulagens. Observações de campo sugerem que as recolhedoras apresentem alta sensibilidade às condições do solo e do material a ser recolhido. O uso de subsolagem nas lavouras é o fato considerado pelos produtores como o maior problema do recolhimento necessitando de alguma alternativa para reduzir os efeitos negativos. A declividade também é vista como entrave, pois o serviço deve ser realizado com menor velocidade, o que reduz a capacidade operacional e interfere no planejamento da colheita. Neste trabalho foram realizados dois estudos: no primeiro analisou-se quali-quantitativamente as operações de varrição e recolhimento em quatro manejos do solo subsolado e, no segundo, verificou-se a capacidade e a eficiência operacionais em quatro faixas de declividade. Os manejos do solo estudados foram: grade após subsolagem; trituração após subsolagem; gradagem e trituração após subsolagem; além de um padrão de comparação sem subsolagem. Para o trabalho de declividade adotou-se entrelinhas com faixas de 0,0 a 5,0%; 5,1 a 10,0%; 10,1 a 15,0% e 15,1 a 20,0% de declividade. Os experimentos foram realizados em duas propriedades no município de Presidente Olegário – MG, sob delineamento disposto em faixas, sendo utilizado o controle estatístico de processos para avaliar a qualidade das operações no primeiro estudo e teste de médias para analisar as capacidades e eficiências operacionais no segundo estudo. No primeiro estudo, a maior qualidade foi obtida para o manejo com grade e triturador após subsolagem, favorecendo menor quantidade de perdas e menor nível de impureza do café recolhido. O manejo apenas com grade após subsolagem apresentou os piores indicadores de qualidade. No segundo estudo, a declividade do terreno a partir de 15,1%, interferem no desempenho da recolhedora, reduzindo significativamente a capacidade de campo efetiva e operacional. Declividades de até 20% não prejudicam a eficiência de limpeza, por outro lado, para eficiência de recolhimento, declividades superiores a 15% reduzem de forma significativa o desempenho das máquinas. / Sweeping coffee harvest is an essential practice in coffee production these days, because the fallen coffee in a natural way added to the fallen by the harvester operation make up 25% of production is in the soil, an amount dependent on several related factors to the plant and used harvesters. In recent years, the mechanization of this process has become common, mainly due to the encumbrance and the unavailability of manpower. However, few studies with these machines difficult the decisions made in respect of their settings. Field observations suggest that the harvesters have high sensitivity to ground conditions and the material to be gathered. The use of subsoiling in the fields is the fact considered by producers as the largest problem of the gathering needing an alternative to reduce the negative effects. The slope is also seen as an obstacle, because the service must be performed with lower speed, which reduces the operational capacity and interferes with the planning of the harvest. This work were realized two studies: the first analyzed qualitative and quantitatively the sweeping and gathering operations in four managements of soil subsoiled and in the second, it was the capacity and operational efficiency in four slopes ranges. The managements of the soil studied were: harrow after subsoiling; crushing after subsoiling; harrowing and crushing after subsoiling; beyond of a standard comparison without subsoiling. For the work of slopes was adopted interrows with tracks 0.0 to 5.0%; 5.1 to 10.0%; 10.1 to 15.0% and 15.1 to 20.0% of slope. The experiments were conducted in two properties in the municipality of Presidente Olegário - MG, Brazil, under design disposed in strips, being used the statistical process control to assess the quality of operations in the first study and mean test to analyze the capacities and operational efficiencies in the second study. In the first study the highest quality is obtained for management with harrow and crusher after Subsoiling, favoring lower amount of losses and lower impurity level of the gathered coffee. The management only with harrow after Subsoiling has the worst indicators of quality. In the second study, the slope of the land, from 15.1%, interferes in the performance of the harvester, significantly reducing the effective field capacity and operational. Slopes up to 20% does not impair the cleaning efficiency, on the other hand, for gathering efficiency, slopes higher than 15% significantly reduces the performance of the machines.

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