To see the other types of publications on this topic, follow the link: Tree crops.
Dissertations / Theses on the topic 'Tree crops'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Tree crops.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Weber, Norbert, and Matthias Meyer. "Land availability for sustainable agricultural tree crops." Adjacent Digital Politics Ltd, 2021. https://tud.qucosa.de/id/qucosa%3A73975.
Full textAbstract:
Prof Dr Norbert Weber from TU Dresden argues that land availability for sustainable agricultural tree crops and a positive perception of this by the official administration both remain challenging hurdles.
2
Brown, Sarah K. "Managing symbiotically-fixed nitrogen on mined land for tree crops." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-11102009-020308/.
Full text
3
Kluthe, John D. "Ferns as a forest farming crop effects of light levels on growth and frond quality of selected speicies with potential in Missouri /." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4587.
Full textAbstract:
Thesis (M.S.)--University of Missouri-Columbia, 2006.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (February 8, 2007) Includes bibliographical references.
4
Hänninen, Kaarina. "Tree-cover crop interactions : birch growth, competition and soil properties /." Oulu : Oulun Yliopisto, 2002. http://herkules.oulu.fi/isbn9514267184.
Full text
5
Langholtz, Matthew Harvey. "Economic and environmental analysis of tree crops on marginal lands in Florida." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0012141.
Full text
6
BENNY, Jubina. "INVESTIGATION ON THE GENETIC BASIS OF ENVIRONMENTAL STRESS IN FRUIT TREE CROPS." Doctoral thesis, Università degli Studi di Palermo, 2021. http://hdl.handle.net/10447/499738.
Full textAbstract:
Plant stress can be divided into two major categories: abiotic stress and biotic stress. Abiotic stress happens when plants are exposed to the environment either physically or chemically. There is an emergency in developing crop varieties that are tolerant to abiotic stresses to ensure food security and safety in the coming years. Multiple abiotic stress like drought, heat, frost at flowering and nutrient deficiency can cause an erratic fruiting behavior or following extreme events, the death of the plants. Plants require an optimal level of nutrients and essential minerals for their growth and development that are mainly acquired from soil by their roots. Nutrient deficiency is an environmental stress that can seriously affect fruit production and quality. In the past decades, agriculturalists relied only on the traditional methods to identify the stresses. In this postgenomic era, called the “omic” era, transcriptional and translational research on model plants has provided many valuable information on many horticultural species.
In the present dissertation, the objective of the first study was to identify, and map key genes involved in drought response on leaves across different crops. The study is the first to provide RNA-Seq data analysis related to transcriptomic responses towards drought across different fruit tree crops. The second study was conducted to identify essential genes involved in general plant abiotic stress conditions and those involved in specific and unique in different abiotic stresses. A pipeline composed of pathway and gene set enrichment analysis, protein-protein interaction networks, and gene visualization tools were employed. The next study aims to identify genes that serve as potential targets to develop cultivars with enhanced drought and salinity resistance and/or tolerance across different fruit tree crops in a biotechnological sustainable way. An “omic” experimental plan was developed to investigate and understand a physiological stress presumably due to nutritional deficiencies causing premature flower bud abscission in pistachio that leads to alternate bearing behavior. The aim of this analysis was to provide insights into the transcript changes between inflorescence buds and fruits in bearing and non-bearing shoots to identify the molecular mechanism causing premature inflorescence bud abscission, which is linked to alternate bearing in the Italian pistachio cultivar Bianca.
Key molecular physiological conclusions were generated based on the identification of conserved gene sets, pathways, and gene networks involved in abiotic stress resistance/tolerance. The experiment provides a valid approach to ask additional questions with respect to how plants respond to stress. Identifying key information in transcriptomic data is very important, especially when the “omic” study deals with plant responses to stresses in field conditions where a high number of variables and disturbing factors may affect the analysis. The proper understanding of plant stress response mechanisms under specific stresses can draw a better view for improving worldwide food production.
7
Westling, Fredrik Anders. "Pruning of Tree Crops through 3D Reconstruction and Light Simulation using Mobile LiDAR." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/27427.
Full textAbstract:
Consistent sunlight access is critical when growing fruit crops, and therefore pruning is a vital operation for tree management as it can be used for controlling shading within and between trees. This thesis focuses on using Light Detection And Ranging (LiDAR) to understand and improve the light distribution of fruit trees. To enable commercial applications, the tools developed aim to provide insights on every individual tree at whole orchard scale.
Since acquisition and labelling of 3D data is difficult at a large scale, a system is developed for simulating LiDAR scans of tree crops for development and validation of techniques using infinite, perfectly-labelled datasets. Furthermore, processing scans at a large scale require rapid and relatively low-cost solutions, but many existing methods for point cloud analysis require a priori information or expensive high quality LiDAR scans. New tools are presented for structural analysis of noisy mobile LiDAR scans using a novel graph-search approach which can operate on unstructured point clouds with significant overlap between trees.
The light available to trees is important for predicting future growth and crop yields as well as making pruning decisions, but many measurement techniques cannot provide branch-level analysis, or are difficult to apply on a large scale. Using mobile LiDAR, which can easily capture large areas, a method is developed to estimate the light available throughout the canopy. A study is then performed to demonstrate the viability of this approach to replace traditional agronomic methods, enabling large-scale adoption.
The main contribution of this thesis is a novel framework for suggesting pruning decisions to improve light availability of individual trees. A full-tree quality metric is proposed and branch-scale light information identifies underexposed areas of the tree to suggest branches whose removal will improve the light distribution. Simulated tree scans are then used to validate a technique for estimating matter removed from the point cloud given specific pruning decisions, and this is used to quantify the improvement of real tree scans. The findings of this iv ABSTRACT v thesis demonstrate the value and application of mobile LiDAR in tree crops, and the tools developed through this work promise usefulness in scientific and commercial contexts.
8
BALAN, Bipin. "INVESTIGATION OF BIOTIC STRESS RESPONSES IN FRUIT TREE CROPS USING META-ANALYTICAL TECHNIQUES." Doctoral thesis, Università degli Studi di Palermo, 2020. http://hdl.handle.net/10447/400369.
Full textAbstract:
In recent years, RNA sequencing and analysis using Next Generation Sequencing (NGS) methods have enabled to understand the gene expression pertaining to plant biotic and abiotic stress conditions in both quantitative and qualitative manner. The large number of transcriptomic works published in plants requires more meta-analysis studies that would identify common and specific features in relation of the high number of objective studies performed at different developmental and environmental conditions. Meta-analysis of transcriptomic data will identify commonalities and differences between differentially regulated gene lists and will allow screen which genes are key players in gene-gene and protein-protein interaction networks. These analyses will allow delivering important information on how a specific environmental factor affects plant molecular responses and how plants activate general stress responses to environmental stresses. The identification of common genes between different biotic stress will allow to gain insight into these general responses and help the diagnosis of an early “stress state” of the plants. These analyses help in monitoring stressed plants to start early specific management procedures for each disease or disorder. In this meta-analysis study, I considered all transcriptomic data related to biotic stresses in fruit tree crops, which are already published. The aim was to determine which genes, pathways, gene set categories and predicted protein-protein interaction networks may play key roles in specific responses to pathogen infections.
9
Ford, Tracey Elaine. "Tennessee tree nursery : from nineteenth century Northern European desire for nature to American industry." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/23947.
Full text
10
Perulli, Giulio Demetrio <1990>. "Secondary treated wastewater as a valuable and safe source for drip irrigating tree crops." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amsdottorato.unibo.it/8981/1/Tesi_Giulio%20Demetrio%20Perulli.pdf.
Full textAbstract:
Wastewater represents a support source for irrigation and mineral nutrients supply in agricultural systems, offering agronomical and environmental advantages. This work investigates the effect of STW (secondary treated wastewater) irrigation on apple and nectarine crops. Physiological, nutritional status and contaminants accumulation in vegetative and reproductive organs were assessed based on the different physiological traits of the two species. Trees were grown, for two consecutive seasons, in pots and drip irrigated with: Tap water (TW), Tap water plus an addition of mineral fertilizer (TW+MF) and Secondary treated wastewater (STW). Furthermore a laboratory trial was carried out to asses two E.coli strains internalization on young GF 677 micropropagated plants. Regarding the pots trial, apple and nectarine tree physiological, vegetative and fruit growth/quality parameters were in most of the cases promoted by STW, compared to TW trees, although TW+MF trees showed the highest values. This response is related to the different amount of nutrients supplied to the trees. Although STW provided a “fertigation-like” effect, results suggest that it did not completely fulfil tree nutrient demand. Treatments affected mainly leaf rather than fruit mineral concentration, with concentrations mostly in the optimal range for all treatments, except the TW, which showed nutritional deficiencies. STW irrigation improved nectarine fruit growth rate and influenced positively apple fruit quality parameters. Heavy metal concentration was unaffected by STW-irrigation with concentrations in fruit tissues within international limits imposed for human consumption in both species. No E.coli and few total coliforms were detected in the vegetative and reproductive tissue of both species. As for the laboratory trial, E.coli strains was able to enter roots but without any translocation in the areal part of the plant, not representing a hazard for human health. The overall results indicate STW as a convenient and safe source for drip irrigating tree crops.
11
Eltahir, Susan. "The management of food-producing trees in the public places of metropolitan Adelaide /." Title page, table of contents and abstract only, 1992. http://web4.library.adelaide.edu.au/theses/09ENV/09enve51.pdf.
Full text
12
BRUNO, MARIA ROBERTA. "Sustainable use and practical application in the industrial sector of permanent crops biomass: Orange tree (C. sinensis L.), Apricot tree (P. armeniaca L.) and Olive tree (O. europea L.)." Doctoral thesis, Università degli studi della Basilicata, 2021. http://hdl.handle.net/11563/149565.
Full textAbstract:
Of the Earth's surface the 30% is occupied by forest and almost 50% is occupied by agricultural crops. Both the forest and agricultural besides producing food, feed, fiber, and a wide range of necessary products like shelter, packaging, clothing, and communications, produce a huge quantity of biomass about 956 Mt of dry matter for agriculture and the forest 18,600 Mt dry weight. Much of forest biomass is used to produce energy and heat while most of the agriculture biomass remains in the field or is burned. The recent EU Directives have encouraged state members to follow circular economy guidelines on waste reuse, especially for waste originating from wood agro-forest biomass. The biorefinery that used the lignocellulosic material has increased the production of biobased material, due to the composition of the biomass. Within the biomass are present lignin, polysaccharides, and extractives. The extractives have a huge potential in the industrial sectors. Orange trees, apricot trees, and olive trees are typical Mediterranean crops and a major feature of the heritage in the Mediterranean basin, where they play an important environmental and economic role. Given the potential of biomass in the different industrial sectors, the research was focused on the valorization of biomass of orange trees, apricot trees, and olive trees. The biomass coming of these trees was selected and bark was separated from the wood. After that different extraction techniques were applied, including maceration, ultrasound-assisted extraction, accelerated solvent extraction, and autoclaving. The extractives obtained were evaluated of the antioxidant capacity with the measurement of total polyphenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), β-Carotene bleaching assay (BCB). Integrating the antioxidant capacity values generated from the different in vitro methods above mentioned was determined the relative antioxidant capacity index (RACI). Results demonstrated the potential antioxidant activity of the bark and wood, not investigated before. Then it is moved on to analyze the molecular compound present in these extract through the LC-MS analyses and GC-MS analyses. The chemical characterization showed the presence of different natural compounds, including polyphenols, alkaloids, and flavonoids. These analyses were necessary to build an industrial product. The extract with the best antioxidant activity and the antioxidant compound was the apricot bark extract through the maceration. Studying the market of cosmetic products it was chosen to make a prototype of face cream. It was necessary to make a cytotoxicity assay both for the extract and for the cream plus the extract. These preliminary assays have demonstrated the possibility of using the extracts from orchards and olive grove in the industrial fields. Therefore, the development of innovative applications that use biomass derivatives could lead to their possible use in the market as a commodity for the chemical or cosmetic industries, giving new added value to the current use of biomass from agricultural practice. Through multi-criteria analysis, it was possible to recognize the sustainability of these cropping models and their ecological function, turning into the preservation of environmental resources, environmental quality, and quality of life.
13
Wildy, Daniel Thomas. "Growing mallee eucalypts as short-rotation tree crops in the semi-arid wheatbelt of Western Australia." University of Western Australia. School of Plant Biology, 2004. http://theses.library.uwa.edu.au/adt-WU2004.0031.
Full textAbstract:
[Truncated abstract] Insufficient water use by annual crop and pasture species leading to costly rises in saline watertables has prompted research into potentially profitable deep-rooted perennial species in the Western Australian wheatbelt. Native mallee eucalypts are currently being developed as a short-rotation coppice crop for production of leaf oils, activated carbon and bio-electricity for low rainfall areas (300—450 mm) too dry for many of the traditional timber and forage species. The research in this study was aimed at developing a knowledge base necessary to grow and manage coppiced mallee eucalypts for both high productivity and salinity control. This firstly necessitated identification of suitable species, climatic and site requirements favourable to rapid growth, and understanding of factors likely to affect yield of the desirable leaf oil constituent, 1,8-cineole. This was undertaken using nine mallee taxa at twelve sites with two harvest regimes. E. kochii subsp. plenissima emerged as showing promise in the central and northern wheatbelt, particularly at a deep acid sand site (Gn 2.61; Northcote, 1979), so further studies focussed on physiology of its resprouting, water use and water-use efficiency at a similar site near Kalannie. Young E. kochii trees were well equipped with large numbers of meristematic foci and adequate root starch reserves to endure repeated shoot removal. The cutting season and interval between cuts were then demonstrated to have a strong influence on productivity, since first-year coppice growth was slow and root systems appeared to cease in secondary growth during the first 1.5—2.5 years after cutting. After decapitation, trees altered their physiology to promote rapid replacement of shoots. Compared to uncut trees, leaves of coppices were formed with a low carbon content per unit area, and showed high stomatal conductance accompanied by high leaf photosynthetic rates. Whole-plant water use efficiency of coppiced trees was unusually high due to their fast relative growth rates associated with preferential investments of photosynthates into regenerating canopies rather than roots. Despite relatively small leaf areas on coppice shoots over the two years following decapitation, high leaf transpiration rates resulted in coppices using water at rates far in excess of that falling as rain on the tree belt area. Water budgets showed that 20 % of the study paddock would have been needed as 0—2 year coppices in 5 m wide twin-row belts in order to maintain hydrological balance over the study period. Maximum water use occurred where uncut trees were accessing a fresh perched aquifer, but where this was not present water budgets still showed transpiration of uncut trees occurring at rates equivalent to 3—4 times rainfall incident on the tree belt canopy. In this scenario, only 10 % of the paddock surface would have been required under 5 m wide tree belts to restore hydrological balance, but competition losses in adjacent pasture would have been greater
14
Gunathilaka, R. P. Dayani. "Economic impacts of climate change on perennial plantation tree crops: the case of tea production in Sri Lanka." Thesis, Griffith University, 2018. http://hdl.handle.net/10072/377583.
Full textAbstract:
Agriculture is one sector of the economy which is highly vulnerable to climate change because of the natural relationship between environment, particularly temperature and water availability, and agricultural productivity. Changing climate is increasingly affecting high-value perennial plantation crops such as tea, rubber, coconut, palm oil, and coffee which generate significant export revenues and provide a major source of employment for rural populations in developing countries. Many studies in the literature have focused on climate change impacts on major annual crops; however, to date, there have been very few assessments of the economic impacts of climate change on perennial plantation agriculture. This thesis therefore seeks to estimate the impacts of climate change on two important aspects of plantation agriculture - crop production and labour demand - for the case of the tea plantation sector in Sri Lanka, as an example of a high-value perennial plantation crop in a developing country. The thesis also aims to identify enablers and barriers of adaptation to climate change for this sector of Sri Lanka’s economy.
The impacts of climate change on production in Sri Lanka’s tea plantations are studied at estate-level (the primary decision making production unit) across all of the country’s tea growing regions using monthly resolution primary data for the period 2000-2014. The study employs a novel two-stage panel data approach to analyse weather and climate change effects on tea production and then to estimate production impacts for the short-, medium- and long-term future under three different global emissions scenarios. These analyses indicate that a hotter and wetter climate will have a detrimental effect on production. In high, medium and low emissions futures, the predictions show a negative proportional impact on production from increased rainfall and increased average temperature. On average across the data sample, a 12% decline in annual tea production is predicted under a high emissions scenario by 2050.
The impacts of climate change on labour demand in tea plantations in Sri Lanka are investigated by implementing a panel structural model of profit maximisation based on a normalised quadratic functional form. The analysis uses historical primary data on estate profits, input prices and output prices, together with monsoonal rainfall, temperature and wet days for years between 2002-2014 to quantify climate impacts on estates’ demand for labour. Anticipated changes in rainfall are predicted to reduce annual labour demand by 2.6% across the tea plantation sector. This could have considerable social and welfare implications, particularly for the Indian Tamil women who comprise the majority of the sector’s workforce.
Plantation agriculture is likely to be highly vulnerable to climate change because of its reliance on rain-fed production, long economic life span and the inability to easily switch crops due to high upfront capital costs. These distinct differences between annual and perennial agriculture, and the important role which plantation cropping plays in developing world agriculture, suggest that it is important to identify factors which affect choice of climate adaptation options in perennial crop production. Comprehensive knowledge of available adaptation options is of utmost importance if Sri Lanka’s tea estate managers are to counteract production losses from climate change and maintain their competitiveness in the international market. This is also vital for efficient and effective channeling of society’s resources to address the consequences of climate change. Employing data derived from face-to-face interviews with 50 tea estate managers in Sri Lanka, this study examines factors affecting choice of preferred adaptation options, barriers to adaptation and associated policy implications for tea production in Sri Lanka, as an example of a perennial tree crop system in a developing country.
Tea estate managers are already adapting to a changing climate; however, particular adaptation methods are only adopted in some situations and locations. Multinomial logit analysis of data from estate manager interviews indicates that availability of information on climate change, company size, tea growing elevation, and observed increases in temperature and rainfall are key factors influencing the choice of preferred adaptation option. Analysis also finds that barriers such as a lack capital, inadequate access to near-term and medium-term climate knowledge, and poor governmental and institutional support may prevent estate managers from experimenting with new adaptation options. Policies should, therefore, be aimed at promoting new adaptation options through information exchange between stakeholders and integrating climate change adaptation with Sri Lanka’s national sustainable developmental goals. The primary message of the adaptation analysis in this study is that governmental and institutional support and involvement are critical requirements for facilitating effective adaptation.
Findings from the thesis will help inform decision makers of the likely impacts of climate change on plantation cropping systems, and provide insights into barriers to adaptation and potential policy responses to improve the effectiveness of adaptation.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
Full Text
15
Pakiam, Geoffrey Kevin. "Smallholder involvement in tree crops in Malaya, with special reference to oil and coconut palms in Johor, 1862-1963." Thesis, SOAS, University of London, 2017. http://eprints.soas.ac.uk/26485/.
Full text
16
Dorr, Hilary R. "Non-operator and farm operator landowner interest in agroforestry in Missouri." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4610.
Full textAbstract:
Thesis (M.S.) University of Missouri-Columbia, 2006.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (May 20, 2007) Vita. Includes bibliographical references.
17
Spokevicius, Antanas Vytas. "The use of induced somatic sectors for the elucidation of gene function and developmental patterns in xylogenic tissue /." Connect to thesis, 2006. http://eprints.unimelb.edu.au/archive/00002300.
Full text
18
Rector, Ryan Jeffery. "The Use of an Automatic Spot-Sprayer in Western Tree Crops and Weed Control in a Pecan Orchard Using Preemergence and Postemergence Herbicides." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/194435.
Full textAbstract:
Weed control is typically achieved by broadcast spraying postemergence herbicides on the entire orchard floor which wastes chemical by spraying bare ground. Growers can account for spatial variation in weed density and only spray weedy areas instead of applying herbicide to entire fields by using the automatic spot-sprayer, WeedSeeker sprayer. We conducted field experiments in flood- and microsprinikler-irrigated lemon orchards, and flood- and sprinkler-irrigated pecan orchards to measure the amount of herbicide applied, weed control, tree yield, and the economic value of adopting the WeedSeeker sprayer compared to conventional boom spray technology. The WeedSeeker sprayer reduced cumulative herbicide use by at least 36% compared to the conventional boom sprayer at all sites. Weed control obtained using the WeedSeeker sprayer was usually similar to the conventional boom sprayer. There were no effects of the treatments on yield at any location. The partial budget analysis, used to determine the economic value of adopting the technology, showed that as the area of the orchard and the cost of the herbicide increased, the time to recover the initial investment in the WeedSeeker sprayer decreased. The investment in the technology can typically be recovered in less than five years in Arizona lemon and pecan orchards.We also conducted greenhouse experiments to determine the effect of various sensitivity settings and leaf area on the operational efficiency of the WeedSeeker sprayer. The WeedSeeker sprayer did not detect and spray all broadleaf and monocot plants unless a sensitive setting was used. The WeedSeeker sprayer was more efficient when detecting broadleaf plants compared to monocot plants. Our results indicate that operating the WeedSeeker sprayer using a sensitive setting (sensitivity level 2) will result in the most efficient detection of weeds.Finally, field studies were conducted in a non-bearing pecan orchard to evaluate weed management systems using various postemergence and preemergence herbicides. Most postemergence herbicides controlled the weed species present in the orchard. Tank mixing the herbicides generally resulted in greater control compared to applying them alone. All preemergence herbicides reduced the weed emergence compared to not using a preemergence herbicide. No pecan tree damage was observed in any treatment.
19
Sande, Bueno Dickens. "Pollarding and root pruning as management options for tree-crop competition and firewood production." Thesis, Stellenbosch : University of Stellenbosch, 2003. http://hdl.handle.net/10019.1/2355.
Full textAbstract:
Thesis (MScFor) (Forest and Wood Science)--University of Stellenbosch, 2003.Planting of upperstorey trees along boundaries has been introduced in KabaleUganda with good reception from local farmers. Trees have been planted along agricultural fields, but both Alnus acuminata and Grew/lea robusta out-compete food crops. Managing competition between trees and crops for water, light, and nutrients to the benefit of farmers is a determinant of successful agroforestry. The scarcity and fragmentation of farmland coupled with the hilly nature of Kabale, highlights the need to address the question of tree-crop competition for resources if the technology of on-farm tree planting is to be widely disseminated and adopted in its different guises. Five-year old trees of A acuminata and G. robusta were subjected to treatments of pollarding, or a combination of pollarding and one side root pruning and compared with unpruned controls. The objectives were to assess their potential in reducing competition with food crops and providing firewood to farmers as well as their effects on tree growth. Pollarding has many benefits to farmers because it provides firewood and stakes for climbing beans, it reduces competition for resources between trees and crops and enables continued tree planting on-farm. Continued on-farm tree planting alleviates problems associated with limited land and contributes to environmental resilience. To ensure this, effect of pollarding and root pruning of upperstorey boundary trees of A acuminata and G. robusta was tested on 12 farmers' fields in Kabale. Food crops (beans and maize) grown in the sequence beans-maize-beans, grew very well at less than 50 em from trees that had been pollarded and root pruned one side. In general, pooled data from 12 sites over 5 m away from trees indicated that a combination of pollarding and root pruning increased bean yield by 240% and maize by 154%, while pollarding alone increased bean yield by 181% and maize yield was increased by 123% in comparison to non-pruned trees. However, pollarding and root pruning treatments reduced tree growth rates.Notable was more competition with crops by A. acuminata than by G. robusta. This was attributed to differences in root architecture, diameter at breast height (dbh) sizes, crown spread and crown density between the two species. Five-year-old A. acuminata had bigger dbh (12.40 cm), wider crown spread (6 m) and a dense crown, while G. robusta had dbh 10.82 em, 3 m crown spread and a light crown. A. acuminata also had more branches per tree (34) compared to G. robusta with only 25. These factors influence water uptake, light penetration through the canopy and transpiration rates, and thus affect tree-food crop competition. It is concluded that pollarding and root pruning have a great potential to reduce tree-crop competition, thereby paving the way for continued on-farm tree planting. The effect of pollarding on timber quality, moisture seepage into timber through the cut surface, if any, and the extent of its damage are areas for further research. The rate of root recovery is also to be followed closely to determine an appropriate frequency for cutting back of roots to recommend to farmers how often they need to prune their trees. It is also suggested that a thorough study be conducted on the amount of water uptake from the soil by each of the species Alnus acuminata and Grevillea robusta. This will help further explain the differences in competition between the two species.
20
Walker, Keitirele Patricia. "Productivity of four fodder tree species, their nutritional value and potential role in ruminant production in Eastern Botswana." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/1421.
Full textAbstract:
Thesis (PhD (Forest and Wood Science))—University of Stellenbosch, 2007.Sustainable livestock production in semi-arid Botswana could be improved through tree planting on-farm to provide much needed protein and shade. Such action can be encouraged if the growth, productivity, nutritional value of trees and their contribution to mass gain of livestock are known.. A study at Malotwana investigated two indigenous species, Acacia galpinii and Faidherbia albida, and two exotic species, Leucaena diversifolia and L. leucocephala, at three spacings in a randomised complete block design replicated five times. The three spacings represented 400, 317 and 241 trees per hectare. The study was conducted over 6.5 years. Indigenous trees were sampled biennially and exotics annually to evaluate crown width, height, stem diameter, stem number and stem volume index. Complete plant harvesting of exotic trees at 2.5, 4.5 and 6.5 years evaluated agroforestry production. Leaves from all four species and pods of exotic species were analysed for chemical composition. Two groups of eight lambs were balanced for mass at selection for an on-farm feeding trial. Browse from exotic trees, comprising a 2:1 ratio of pods to leaves, was fed at 30% as supplement to hay to one group whose mean mass was contrasted with that of the control group fed sorghum bran at 30%. A. galpinii was a promising species, adaptable to planting away from its origin. Its crown width ranged from 5.86 m in high density plots to 6.08 m at low density and was significantly different among stands (p = 0.0406) at 6.5 years. Diameter at breast height (dbh) was significantly different among stands aged 6.5 years (p = 0.0003) and ranged between 10.38 cm at high density to 12.48 cm in low density plots, demonstrating a capacity to provide both shade and poles on-farm. At 4.5 years, F. albida attained a mean height of 4.5 m and 4.5 cm in dbh but suffered 67% mortality during a severe drought. Annual fodder production of 0.647 and 0.996 metric tonnes ha-1 for leaves and pods of L. diversifolia and 1.237 and 1.431 for L. leucocephala was recorded in years of average rainfall. Yields of 0.3 and 0.59 metric tonnes ha-1 were recorded for both species in the driest year. Equally good agroforestry production was obtained from both low and high density stands suggesting that low density plantings, which foster higher plant survival and reduce disease incidence, are best suited to the semi-arid conditions of Botswana. The crude protein of leaves ranged between 16.26 (L. diversifolia) and 25.25% (F. albida). They were highly digestible with more than twice the calcium content livestock require. Crude protein and digestibility measures were significantly different among leaves and varied significantly at different spacings (p<0.0001). Pods of the exotic species contained significantly more protein than the leaves (p<0.0001). Lambs supplemented with browse gained 102.33 g per animal per day while the control group gained 83.95 g. There were significant differences between groups during growth (p<0.05). Growing of A. galpinii, complemented with L. diversifolia and L. leucocephala, can supply short and long term feed, and greatly enhance livestock production while diversifying farm feed sources
21
Noorduijn, Saskia L. "Temporal and spatial effects of a long term large scale alley farming experiment on water table dynamics : implications for effective agroforestry design." University of Western Australia. School of Environmental Systems Engineering, 2009. http://theses.library.uwa.edu.au/adt-WU2010.0102.
Full textAbstract:
[Truncated abstract] Removal of native vegetation to facilitate traditional agriculture practices has been shown to reduce ecosystem health, and restricts the native habitat. The subsequent change in the predominant vegetation water use patterns has altered the catchment water balance, and hydrology which results in land degradation through such processes of salinisation and water logging. More recently, moves toward more sustainable farming practices have been taken to help re-establish catchment hydrological equilibrium and improve catchment ecosystem services. Agroforestry is one such vehicle for this reestablishment. Perennial native vegetation has been shown to have a significant effect on catchment processes, mitigating any further degradation of the land. The effect of alternating native perennial tree belts with traditional broad acre agriculture in the alleys, referred to as alley farming, is investigated in this thesis due to the potential environmental and economic benefits that can result. This thesis investigates the impact of tree belts upon the water table and aims to gauge the ability of alley farming at controlling recharge within the low-medium rainfall zone on the valley floor. The basis of this research is the analysis of data collected from the Toolibin Alley Faring Trial. This experiment was established in 1995 to assess the viability of alley farming and incorporates different combinations of belt width, alley width and revegetation density. Transects of piezometers within each design have been monitored from October 1995 to January 2008. The piezometers were sporadically monitored over this period on a total of 39 dates. ... To further understand the response observed in the water table data, in depth hydrograph analysis of the control piezometer water levels was conducted. The statistical analysis demonstrates that the belts are having a very limited impact on the water table morphology, this is associated with the restricted use of groundwater by the perennial tree belts due to the poor quality, has been applied. This explains why there is limited signature of increased water table depth in the statistical analysis; there is evidence that alley farming as a means of reducing recharge may work however the overriding control on the trial are the rainfall trends rather than perennial growth. The low perennial biomass production at the site is an effect of limited water resources; however a significant distinction can be made between the water table depth and variability beneath high and low biomass belts. There are three main controls at the site; climate, development of perennial biomass and development of perennial root systems (both vertically and laterally). The regional climatic trends will influence water table levels creating a greater soil water storage capacity; therefore the contribution of soil water to transpiration rates will enable the tree belts to have some impact on recharge. Of the alley farming designs tested, the optimal planting density and belt/alley design, from an economic perspective, is identified as having a 4m belt width which generated the greatest biomass. As a means of controlling recharge at the site the effectiveness of alley farming is limited due the shallow saline water table limiting perennial growth.
22
Pandeya, Hemant Raj. "Carbon and nitrogen flux dynamics in highly weathered tropical mango soils: Effect of leaf litter and nitrogen fertiliser." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/232828/1/Hemant%20Raj_Pandeya_Thesis.pdf.
Full textAbstract:
This thesis is a comparative study of carbon and nitrogen flux dynamics following sole and combined application of mango leaf litter mulch and inorganic fertiliser in highly weathered tropical mango orchard soils. In doing so, the thesis investigated litter decomposition dynamics and litter carbon mass balance and provided baseline datasets of seasonal and annual reactive nitrogen losses (through hydrological and gaseous pathways) under the tropical environmental conditions of Northern Territory Australia.
23
Afreh-Nuamah, K. "Spray distribution in a tree crop." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/38212.
Full text
24
Demiris, John. "Radar cross section of a planar fractal tree." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/27232.
Full textAbstract:
Electromagnetic scattering from trees and vegetation is of prime importance in radar and remote sensing. The actual problem of scattering from trees is rather complicated and involves three dimensional scattering from lossy, electrically large, and randomly oriented objects. In this thesis, the radar cross section of a planar fractal tree is considered. Although a planar tree is far from being real, scattering from it shed light on the scattering phenomenon from an actual tree. The planar tree is generated using fractal geometry and its branches are considered perfectly conducting. The tree is illuminated by a plane wave and the problem is solved using the moment method. Data is presented for the radar cross section for different branching angles of the tree and at different frequencies
25
Yamaguchi, David K. "Interpretation of Cross Correlation Between Tree-Ring Series." Tree-Ring Society, 1986. http://hdl.handle.net/10150/261724.
Full text
26
Brenner, Andrew J. "Tree-crop interactions within a Sahelian windbreak system." Thesis, University of Edinburgh, 1991. http://hdl.handle.net/1842/12747.
Full textAbstract:
The advantages of windbreak in terms of reducing soil erosion and providing tree products for farmers in the Sahel are well known. There is less certainty about the effect of shelter on crop growth, the degree of competition for water and light between windbreak and crop, and almost no information on the amount of water a windbreak transpires over a year. Field measurements of millet (Pennisetum typhoides) growth and microclimate behind a young double row neem (Azardirachta indica) windbreak at the ICRISAT Sahelian Centre, Sadore, Niger, were carried out in 1988 and 1989. Measurements of tree transpiration were made using a commercial sap flow meter, along with measurements of tree heights, stem basal areas and leaf areas. The reduction in wind speed produced by the windbreak changed over the season, as a result of the reduction of the porosity of the lower half of the windbreak by the growth of the millet crop on the windward side of the windbreak. Maximum shelter was found at 6h at the beginning of the cropping season and 3h during the middle and end of the season, where h is the height of the windbreak. Factors influencing the magnitude of shelter are discussed.
27
Shyu, Eric. "Latent tree structure learning for cross-document coreference resolution." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/91867.
Full textAbstract:
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 77-79).
Cross Document Coreference Resolution (CDCR) is the problem of learning which mentions, coming from several different documents, correspond to the same entity. This thesis approaches the CDCR problem by first turning it into a structure learning problem. A latent tree structure, in which leaves correspond to observed mentions and internal nodes correspond to latent sub-entities, is learned. A greedy clustering heuristic can then be used to select subtrees from the learned tree structure as entities. As with other structure learning problems, it is prudent to envoke Occam's razor and perform regularization to obtain the simplest hypothesis. When the state space consists of tree structures, we can impose a bias on the possible structure. Different aspects of tree structure (i.e. number of edges, depth of the leaves, etc.) can be penalized in these models to improve the generalization of thes models. This thesis draws upon these ideas to provide a new model for CDCR. To learn parameters, we implement a parameter estimation algorithm based on existing stochastic gradient-descent based algorithms and show how to further tune regularization parameters. The latent tree structure is then learned using MCMC inference. We show how structural regularization plays a critical role in the inference procedure. Finally, we empirically show that our model out-performs previous work, without using a sophisticated set of features.
by Eric Shyu.
M. Eng.
28
Nyamai, D. O. "Crop production in an intercropping system with tropical leguminous trees." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382474.
Full text
29
Hänninen, K. (Kaarina). "Tree - cover crop interactions: birch growth, competition and soil properties." Doctoral thesis, University of Oulu, 2002. http://urn.fi/urn:isbn:9514267184.
Full textAbstract:
Abstract
The main objective of this thesis was to investigate tree - cover crop interactions and soil response in an intercropping system, in which leguminous and grass cover crops were used with birch (red-leaved Downy birch Betula pubescens L.). The investigation was conducted in two field experiments in a nursery and in a greenhouse experiment. In the latter the effect of the water supply in interspesific competition was also investigated. The cover crops in the field experiments were perennial clovers Trifolium pratense L., T. repens L. and T. hybridum L. and annual clovers T. incarnatum L., T. resupinatum L. and T. subterraneum L. and perennial Festuca rubra L. The height, stem diameter, leaf area and nutrient status of the birch were determined, as well as soil nutrient status and microbial characteristics. The cover crops in the greenhouse experiment were T. repens, T. subterraeum and F. rubra. The biomass, height, leaf area, leaf area index, specific leaf area and N concentration of the birch, the biomass and N concentration of the cover crops were measured, and soil N and microbial characteristics, as well. Bare ground was the control in all the experiments.
The perennial clovers and Festuca strongly decreased the birch growth and nutrient status, but the annual clovers sown in midsummer in the field experiments provided about as good growth as bare ground. In the greenhouse experiment all cover crops were effective competitors with the birch. The soil NO3-N was, in general, the highest on bare ground and second highest in the annual clover plots. Though there were, in general, only minor differences in the soil nutrient concentrations between the treatments, there were significant differences in the tree growth and nutrient concentrations. The interspecific competition in this kind of intercropping system is mainly belowground. The growth reduction in the birch was mainly due to competition for nitrogen but water seems to play an important role in regulating the competitive interaction between the birch and cover crops. The competition for these resources seems to be most crucial at the beginning of the growing season. The microbial biomasses and soil respiration were greatest in the Festuca and perennial clover treatments, which may indicate that microorganisms together with these cover crops may seriously compete with birch for nutrients.
Intercropping system is complex and comprises both negative and positive influences. In order to minimize negative competition effects, the cover crop should be non-competitive or the ground should be kept free of vegetation at the beginning of the growing season. By improving soil microbial characteristics, the vegetative ground covers make this cropping system one possiblity towards sustainability in the long-term.
30
Heyerdahl, Emily K., and Steven J. McKay. "Condition of Live Fire-Scarred Ponderosa Pine Trees Six Years after Removing Partial Cross Sections." Tree-Ring Society, 2001. http://hdl.handle.net/10150/251619.
Full textAbstract:
Our objective was to document the effect of fire-history sampling on the mortality of mature ponderosa pine trees in Oregon. We examined 138 trees from which fire-scarred partial cross sections had been removed five to six years earlier, and 386 similarly sized, unsampled neighbor trees, from 78 plots distributed over about 5,000 ha. Mortality was low for both groups. Although mortality was significantly higher for the sectioned trees than their neighbors (8% versus 1 %), removing a partial section did not appear to increase a tree's susceptibility to death from factors such as wind or insect activity. Specifically, the few sectioned stems that broke did so well above sampling height. Most sectioned trees (79 %) had evidence of insect activity in 1994/95, while only an additional 5% had such evidence in 2000. Mortality among sectioned trees in this study was low probably because we removed relatively small sections, averaging 7 cm thick and 8% of the tree's cross-sectional area, from large trees of a species with effective, resin-based defenses against insects and pathogens. Sampling live ponderosa pine trees appears to be a non-lethal method of obtaining information on past fire regimes in this region because it only infrequently led to their death in the early years after sampling.
31
Murray, Edward Thomas. "Harvesting crops between the trees : a study of recreation valuation." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28291.
Full textAbstract:
A non-market valuation of recreation activities on private forest land is undertaken to provide information for integrated forest management decision making. The Contingent Valuation Method is applied, through the use of a mailed questionnaire to a random sample of the households within the Capital Regional District
on Vancouver Island, to estimate willingness-to-pay values and derive potential gross benefits for hunting, fishing and camping on the study area. Recreation activity participation levels and socio-economic characteristics of participants are discussed for each activity on the landbase. Recreation activities,
in particular fishing, have a good potential for producing substantial benefits on the study area.Forestry, Faculty of
Graduate
32
Tran, Xuan Tri. "Les plantations d'hévéa en Cochinchine (1897-1940)." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0016/document.
Full textAbstract:
Dès la conquête de la Cochinchine en 1862, l’Administration coloniale et des particuliers français exploitèrent l’agriculture locale et y développèrent l’économie. Ils tentèrent de faire l’essai et d’introduire diverses cultures, en particulier des arbres à caoutchouc. L’année 1897 marqua le début de l’hévéaculture de Cochinchine, lorsqu’on planta avec succès près de deux mille hévéas brasiliensis. La superficie de l’hévéaculture en Cochinchine se développait prodigieusement, allant de cent hectares à la fin du XIXème siècle à près de cent mille hectares au début des années trente, grâce d’une part à des capitaux provenant de la Métropole et, d’autre part à des mesures d’encouragement du Gouvernement colonial. Les plantations d’hévéa attirèrent les travailleurs locaux, surtout en provenance du Tonkin et de l’Annam, à raison d’une dizaine de mille, parfois une vingtaine de mille par an.Parallèlement à l’extension des superficies plantées, la production du caoutchouc de la colonie s’accrut rapidement, allant d’un peu plus d’une tonne en 1908 à plus de soixante mille tonnes en 1939. Les plantations d’hévéa devinrent l’une des cultures les plus importantes de Cochinchine à l’époque coloniale française. Non seulement elles apportèrent la fortune aux planteurs de la colonie, mais elles assurèrent une partie, et depuis 1938, la totalité des besoins de caoutchouc de l’industrie métropolitaine. Les plantations d’hévéa de Cochinchine représentaient un symbole de la colonisation agricole française, mais aussi hélas l’une des pages noires de l’histoire du colonialisme français au Vietnam par l’exploitation brutale des planteurs envers les travailleurs vietnamiensAs early as the conquest of Cochinchina in 1862, the colonial administration and French individuals exploited the local agriculture and developed the economy there. They tried to experiment and introduce various crops, especially rubber trees. The year of 1897 marked the beginning of the rubber plantation of Cochinchina, when two thousand rubber trees brasiliensis were successfully planted. The area of rubber tree plantation in Cochinchina grew tremendously, ranging from one hundred hectares at the end of the 19th century to nearly one hundred thousand hectares in the early 1930s, because of, on the one hand, the capital invested from the metropolis, and, on the other hand, the measures of encouragement taken by the colonial Government. The rubber plantations attracted local workers, mainly from Tonkin and Annam, at a rate of about 10.000, sometimes 20.000 persons a year. In parallel with the extension of the area of rubber plantation, the colonial rubber production rapidly increased from just over one tonne in 1908 to more than 60.000 tons in 1939.The rubber tree plantation became one of the most important crops of Cochinchina during the French colonial era. Not only they brought fortune to the planters of the colony, but they secured a part, and since 1938, the whole of the rubber demands of the metropolitan industries. The Cochinchina rubber plantations represented a symbol of French agricultural colonization and, unfortunately, one of the black pages of the history of French colonialism in Vietnam by the brutal exploitation of Vietnamese workers by rubber planters
33
Bellow, John G. "Fruit-tree-based agroforestry in the western highlands of Guatemala an evaluation of tree-crop interactions and socioeconomic characteristics /." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0003920.
Full text
34
Venturieri, Giorgini Augusto. "Floral biology of cupuassu (Theobroma grandiflorum (Willdenow ex Sprengel) Schumann)." Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386982.
Full textAbstract:
Cupuassu (Theobroma grandiflorum), one of the most profitable crops of Amazonia, is now attracting world-wide attention as an exotic fruit, used in juices, ice cream and sweets. It is a shade tolerant tree that can be grown as a component of agroforestry systems. Nevertheless it is still a wild species and little is known about its biology. Floral biology of cupuassu was studied in Belem-Brazil during 2 floweringfruiting seasons between June 1991 and December 1993. Flowering occurs in the drier period of the year. Flowers commence opening at any time of the day, but open fully at the end of afternoon. The anthers dehisce and the stigmas are receptive as soon as the flowers are fully open. Stigmas remain receptive until 10:00 am the following day. Throughout this period, the pollen grains remain viable. The flowers have a complex morphology which favours allogamy. The species is also self-incompatible. Experimental pollinations, using compatible pollen grains, have shown that a flower which receives 60 compatible pollen grains has 20% probability of setting fruit; a flower which receives more than 400 pollen grains always sets fruit. However, only around 2% of naturally pollinated flowers receive more than 60 pollen grains. A stingless bee, Plebeia minima, is considered an effective pollinator of cupuassu. Another stingless bee, Trigonisca pediculana, also visits cupuassu flowers. Both bees are small insects, which are unlikely to fly very far. Ants (Wasmannia sp.) and weevils (Baris sp.) were considered secondary pollinators, unlikely to promote effective pollinationsFruits mature during the wet period of the year, approximately 5.5 months after the flowers open. The limited and irregular fruit set is probably caused by scarcity of pollinators. The transformation of cupuassu to a plantation crop will therefore require conditions which favour natural pollinators and their access to receptive and compatible flowers
35
Boshoven, Anne Elizabeth. "Arboreal adventure: A cross curricular unit on trees." CSUSB ScholarWorks, 1997. https://scholarworks.lib.csusb.edu/etd-project/1423.
Full text
36
Sencan, Secil. "Decision Tree Classification Of Multi-temporal Images For Field-based Crop Mapping." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605503/index.pdf.
Full textAbstract:
ABSTRACT
DECISION TREE CLASSIFICATION OF MULTI-TEMPORAL IMAGES FOR FIELD-BASED CROP MAPPING
Sencan, Seçil M. Sc., Department of Geodetic and Geographic Information Technologies Supervisor: Assist. Prof. Dr. Mustafa Tü
rker August 2004, 125 pages A decision tree (DT) classification approach was used to identify summer (August) crop types in an agricultural area near Karacabey (Bursa), Turkey from multi-temporal images. For the analysis, Landsat 7 ETM+ images acquired in May, July, and August 2000 were used. In addition to the original bands, NDVI, PCA, and Tasselled Cap Transformation bands were also generated and included in the classification procedure. Initially, the images were classified on a per-pixel basis using the multi-temporal masking technique together with the DT approach. Then, the classified outputs were applied a field-based analysis and the class labels of the fields were directly entered into the Geographical Information System (GIS) database. The results were compared with the classified outputs of the three dates of imagery generated using a traditional maximum likelihood (ML) algorithm. It was observed that the proposed approach provided significantly higher overall accuracies for the May and August images, for which the number of classes were low. In May and July, the DT approach produced the classification accuracies of 91.10% and 66.15% while the ML classifier produced 84.38% and 63.55%, respectively. However, in August nearly the similar overall accuracies were obtained for the ML (70.82%) and DT (69.14%) approaches. It was also observed that the use of additional bands for the proposed technique improved the separability of the sugar beet, tomato, pea, pepper, and rice classes.
37
Glaspole, Ian. "The human cellular response to peanut (Arachis hypogaea) and cross-reacting tree-nuts." Monash University, Dept. of Pathology and Immunology, 2004. http://arrow.monash.edu.au/hdl/1959.1/9665.
Full text
38
Mir, Saleem Obaidullah. "Enhanced Method Call Tree for Comprehensive Detection of Symptoms of Cross Cutting Concerns." NSUWorks, 2016. http://nsuworks.nova.edu/gscis_etd/962.
Full textAbstract:
Aspect oriented programming languages provide a new enhanced composition mechanism between the functional sub units as compared to earlier non aspect oriented languages. For this reason the refactoring process requires a new approach to the analysis of existing code that focuses on how the functions cross cut one another. Aspect mining is a process of studying an existing program in order to find these cross cutting functions or concerns so they may be implemented using new aspect oriented constructs and thus reduce the complexity of the existing code. One approach to the detection of these cross cutting concerns generates a method call tree that outlines the method calls made within the existing code. The call tree is then examined to find recurring patterns of methods that can be symptoms of cross cutting concerns. The conducted research focused on enhancing this approach to detect and quantify cross cutting concerns that are a result of code tangling as well as code scattering. The conducted research also demonstrates how this aspect mining approach can be used to overcome the difficulties in detection caused by variations in the coding structure introduced by over time.
39
Castellanos, de Varona Maria Elena. "Cross-cultural training program." Theological Research Exchange Network (TREN), access this title online, 2001. http://dx.doi.org/10.2986/tren.108-0017.
Full text
40
Kim, Seoung Bum. "Data Mining in Tree-Based Models and Large-Scale Contingency Tables." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6825.
Full textAbstract:
This thesis is composed of two parts. The first part pertains to tree-based models. The second part deals with multiple testing in large-scale contingency tables. Tree-based models have gained enormous popularity in statistical modeling and data mining. We propose a novel tree-pruning algorithm called frontier-based tree-pruning algorithm (FBP). The new method has an order of computational complexity comparable to cost-complexity pruning (CCP). Regarding tree pruning, it provides a full spectrum of information. Numerical study on real data sets reveals a surprise: in the complexity-penalization approach, most of the tree sizes are inadmissible. FBP facilitates a more faithful implementation of cross validation, which is favored by simulations.
One of the most common test procedures using two-way contingency tables is the test of independence between two categorizations. Current test procedures such as chi-square or likelihood ratio tests provide overall independency but bring limited information about the nature of the association in contingency tables. We propose an approach of testing independence of categories in individual cells of contingency tables based on a multiple testing framework. We then employ the proposed method to identify the patterns of pair-wise associations between amino acids involved in beta-sheet bridges of proteins. We identify a number of amino acid pairs that exhibit either strong or weak association. These patterns provide useful information for algorithms that predict secondary and tertiary structures of proteins.
41
Hla, A. K., E. C. Martin, P. Waller, and D. C. Slack. "Heat Unit Based Crop Coefficient for Grapefruits Trees." College of Agriculture, University of Arizona (Tucson, AZ), 1996. http://hdl.handle.net/10150/220557.
Full textAbstract:
Using portable sap flow sensors, the onset and volume of sap moving up the branches of grapefruit (Citrus Paradisi Macfadyen) trees was monitored on an hourly basis. Reference evapotranspiration (ETo) data was obtained from The Arizona Meteorological Network (AZMET). Crop evapotranspiration (ETc) was estimated from soil moisture measurements using a neutron probe. The threshold temperature limits were delineated from an evaluation of the hourly sap flow responses to cold winter and extreme summer temperatures. The heat based crop curve was derived from a correlation of the crop coefficients with heat unit over one crop year. The heat based crop coefficients were found to be similar to crop coefficients derived by other researchers.
42
Teklay, Tesfay. "Organic inputs from agroforestry trees on farms for improving soil quality and crop productivity in Ethiopia /." Umeå : Dept. of Forest Ecology, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/2005122.pdf.
Full text
43
Djanibekov, Utkur [Verfasser]. "Trees, crops, and rural livelihoods: Afforestation of marginal croplands in Uzbekistan / Utkur Djanibekov." Bonn : Universitäts- und Landesbibliothek Bonn, 2014. http://d-nb.info/1080591664/34.
Full text
44
Ssekabembe, Charles K. "Interactions at the tree/crop interface in a maize/black locust alley cropping system /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487780865410086.
Full text
45
Kochenderfer, Jeffrey Davis. "Herbicide Hardwood Crop Trees Release in Central West Virginia." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/44187.
Full textAbstract:
Repeated partial cutting in the Appalachian hardwood
region has often favored the development of tolerant
species like American beech (Fagus grandifolia Ehrh.)
and stands with a high proportion of cull trees.
Crop tree release is a widely recommended practice to
improve species composition and growth rates in these
unevenaged structured stands. Chemical control offers
some distinct advantages from the standpoint of safety
and residual stand damage, over mechanical methods.
Control of American beech was the primary focus of this
study. Beech is a low value timber tree, normally considered
difficult to control. It is a major competitor to more
valuable trees, especially on better sites in the Appalachians.
Research plots were established in hardwood stands at three sites in central West Virginia to evaluate the effectiveness of glyphosate (Accord), imazapyr (Arsenal AC and Chopper), and triclopyr (Garlon 3A and Garlon 4) using the hack-and-squirt application method and low volume basal spray treatments. In the injection treatments .051 fl oz (1.5 ml) of solution was used per inch of diameter (dbh). The basal spray treatments used 0.101 fl oz (3 ml) of solution per inch of diameter. The following concentrations were used: Accord (65.2%), Arsenal AC (7.5%), Garlon 3A (50%), Garlon 4 (26.25%), and Chopper (6.25% ). These concentrations were determined by using the highest costing injection and basal treatment at the lowest recommended labeled rate as standards, Garlon 3A and Chopper respectively. Eighteen 0.1 acre plots were systematically located at each study site where crop trees were present and to maximize the number of American beech on each plot. Crop trees, mostly black cherry (Prunus serotina Ehrh.) were chosen on a 0.025 acre subplot established at each plot center. All beech two inches and larger on the 0.1 acre plots and competing trees touching crop trees were treated in June 1998. The treatments were evaluated in September of 1998 and again in June of 1999. A numerical rating system ranging from 1-7, (0-100% crown affected), which utilized visual symptoms, was used to evaluate the efficacy of each treatment. Trees receiving a rating of 5 (75 % crown control) or greater were considered controlled. The relationship between the kinds of herbicide, application method, and numerical rating were analyzed by means of one-way analysis of variance with an incomplete random factorial design.
The most effective treatments for the three month evaluations were the Accord and Garlon 3A injection treatments.
Average beech crown control ranged from 95-99% for Accord to 96-99% for Garlon 3A across all study sites.
The basal spray treatments were not effective. Average crown control ranged from 1-22%, across all study sites.
Accord, Garlon 3A, and Arsenal AC were the most effective treatments for the 12 month evaluations, with average
beech crown control ranging from 99-100% across all study sites. The imazapyr treatments (Arsenal Ac and Chopper)
had adverse effects on the crop trees and are not recommended for hardwood crop tree release. The cost effectiveness
based on treatment costs and the amount of basal area (BA) controlled were averaged for all study sites. The average
treatment costs based on the 12 month evaluations expressed in dollars/ft2 BA controlled were as follows: Accord ($0.91),
Garlon 3A ($1.04), Arsenal AC ($0.84), Garlon 4 ($15.09), and Chopper ($7.74).
NE-TWIGS was used to predict future composition and value of the projected stands. The stem injection treatments decreased the amount of beech and increased the amount of black cherry sawtimber thereby dramatically increasing the future value of the stands. Real rates of return were calculated for the stem injection (8.81%) and low-volume basal spray (-0.81%).
Master of Science
46
Chioino, Jamil, Ivan Contreras, Alfredo Barrientos, and Luis Vives. "Designing a decision tree for cross-device communication technology aimed at iOS and android developers." Association for Computing Machinery, 2018. http://hdl.handle.net/10757/624656.
Full textAbstract:
El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.This analysis proposes a decision tree for selecting cross-device communication technologies for iOS and Android mobile devices. This tree accelerates the selection of cross-device technologies by taking into account known use cases of interaction. Five different communication technologies were tested (Real-time Multiplayer, Nearby Messages, PeerJS, iBeacon and Eddystone) by means of 13 proof of concept applications distributed between both operating systems (Android-iOS, iOS-iOS, Android-Android) and the design of 20 architecture diagrams of three types: sequence (connection to services and message sending), deployment and component. The decision tree was validated by mobile development experts resulting in a maximum reduction of up to 30 days of technology selection research. The effectiveness of the tree as a tool is 60%, its usefulness 80% and its ease of comprehension 90%, according to the results obtained from the experts.
Revisión por pares
47
Haggar, Jeremy. "Nitrogen and phosphorus dynamics of systems integrating trees and annual crops in the tropics." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306403.
Full text
48
De, Leon Maria P. "Immunological and molecular characterisation of major peanut allergens and their cross-reactive components in tree nuts." Monash University, Dept. of Pathology and Immunology, 2004. http://arrow.monash.edu.au/hdl/1959.1/9673.
Full text
49
Parisi, Rosaria. "Deficit Irrigation Strategies on young orange trees (cv Tarocco Sciara)." Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1335.
Full textAbstract:
The economical sustainability of citrus orchards has to cope with the availability of water resources. One way to optimise water resources is to employ deficit irrigation (DI) strategies. DI effects on some physiological characters of young orange orchards were analysed. The orchard includes 300, 4-years old, plants located at the CRA-ACM experimental farm in Lentini, Sicily (37° 20 N; 14° 53 E). Four irrigation strategies were replicated 4 times: (i) Subsurface drip irrigation, supplying 75% IR (irrigation requirement), (ii) Partial root-zone drying, supplying 50% IR, (iii) Regulated deficit irrigation, supplying 50-100% IR, depending on crop phenological phases and (iv) Surface drip irrigation, supplying 100% IR. The IR was calculated using the Penman-Monteith approach, by assuming a crop coefficient of 0.45, and correction coefficients accounting for the localized irrigation. On selected plants, measurements of LAI, PAR, xylematic potential, canopy temperature, gas exchanges, trunk diameter and shoot number were carried out. Soil water content (SWC) was monitored by using Time (and Frequency) Domain
Reflectometry. Preliminary results, obtained during the 2011 season, showed that: (i) xylematic potential and stomatal conductance were slightly variable between the investigated treatments with values quite below the stress condition, (ii) LAI and PAR were slightly variable between each plant and treatments, (iii) SWC was below the field capacity, (iv) trunk diameters were quite similar among the analysed plants.
50
Ghezehei, Solomon Beyene. "Plant productivity, radiation interception and water balance as indicators of tree-crop interactions in hedgerow intercropping systems : a Jatropha - Kikuyu case study." Thesis, University of Pretoria, 2012. http://hdl.handle.net/2263/40252.
Full textAbstract:
The potential of agroforestry to alleviate problems related to scarcities of arable land, water, food and fuel
wood is subject to understanding system functioning and implementing and managing an efficiently
designed system. The objectives of this study were to understand interactions and productivity of a
hedgerow intercropping system with reference to water and radiation use, and analyse system design and
management scenarios in order to enhance returns. Field trials monitoring soil water, solar radiation and
plant productivity were conducted during 2006-2008 at Ukulinga Research Farm (KwaZulu Natal, South
Africa) using a Jatropha-Kikuyu (Pennisetum clandestinum) hedgerow intercropping system as case study.
In order to extrapolate results, a process-based hedgerow intercropping model was developed by building
intercropping and tree growth into the SWB-2D model. Data collected from the field trials were used to
parameterise and evaluate the model, which was used to analyse hedgerow orientation and spacing to
determine income scenarios of virtual system and to help develop design criteria.
Allometric relationships of Jatropha using basal stem diameter and crown width as predictor variables were
found to be very reliable. Stem diameter was linearly related with wood and branch proportions and
inversely proportional to foliage. Neither below-ground (BG) interspecies competition nor tree spacing had
any significant effects on allometry. Allometric equations were proven valid for accurate, non-destructive
and rapid predictions of tree growth under various growing and non-destructive canopy management
conditions.
When interspecies competition was present, none of the tree spacing/arrangement options tested resulted
in consistently highest tree relative growth rates (RGR). Treatments had no effect on tree RGR when high
water availability and kikuyu dormancy coincided. The single-row treatment (SR) produced the shortest
trees, but generally had the highest stem RGR during low rainfall periods. The standard-spacing treatment
(SS) had the highest RGR during the spring and summer seasons. Jatropha-only treatment (JO) trees were
the tallest and biggest. Treatments affected post-pruning tree height increase, even when rainfall was high.
Length of tree-crop interface (TCI) generally decreased tree yield, especially as trees matured toward their
maximum-yield age (4-5 years). SR trees showed slow response to pruning due to a high TCI. They,
however, exhibited compensatory growth during May to August, when competition for water with grass
was low. BG competition reduced tree nut yield more than tree biomass. Tree spacing/arrangements had
no effect on tree harvest index.
Soil water varied among treatments and was asymmetrically distributed across tree hedgerows. System ET
was generally the highest in SR and lowest in the double-row treatment (DR). Differences were mainly due
to transpiration. Treatments affected tree root distribution, which was inferred using correlations between
tree RGR and soil water deficit (SWD). In JO and SR, fine tree roots were asymmetrically distributed. Their
distribution in DR was essentially symmetrical. Strong vegetative RGR-SWD correlations during the 2007/08
season indicated that tree growth was mainly water-limited. Though DR and SR had comparable tree RGRs,
DR produced less grass than SR. This implied DR had more intensive BG competition than SR. Interspecific competition was severe due to a lack of temporal complementarity between Jatropha and kikuyu and a
shallow soil profile (0.6 m). Tree water uptake predominantly came from the 0.2 – 0.6 depth, which had
about 8.6% of the total root biomass in the profile. There was no clear relationship between intercrop
growth and root distribution. Radiation use efficiency of kikuyu decreased towards tree hedgerows possibly
due to preceding interaction of the irradiance with tree canopy reducing photosynthetically active radiation.
The effect of radiation distribution on tree-crop (T-C) interactions was mainly to magnify effects of water.
Finally, tree spacing/arrangement could be manipulated to optimise radiation and soil water distribution
and intercrop growth.
Predictions of solar radiation distribution, profile water content and tree water use were quite accurate. In
general, intercrop productivity simulations were acceptable. Intercrop growth was overestimated when
rainfall was high and underestimated when rainfall was low. During model calibration, tree woody biomass,
leaf area index, crown width and nut yield were predicted adequately, while leaf dry mass was
overestimated. During model validation, woody biomass and crown width were simulated reasonably well.
However, foliage biomass, leaf area index and nut yield were overestimated. Overall, adequacy of the
model for simulating tree productivity was established. Using scenario modelling, model capabilities to
facilitate design/planning and management of hedgerow intercropping systems and interpretation of model
outputs were demonstrated. The model can be used to determine the T-C trade-off that yields maximum
income. By selecting best-case row orientation and spacing scenarios using the model, and keeping in mind
values of tree and intercrop yields, system returns can be maximised. Tree crown growth can also be
predicted in order to decide on the extent and timing of pruning.
The present model is applicable to any potential tree-intercrop combination. It should be linked to a
nutrient simulator of SWB, its component, and appraised further by considering shade-intolerant and
shade-loving crop species, along with evergreen and deciduous tree species. This provides model users
with numerous T-C combinations to choose from. Various tree spacing/arrangement options can also be
explored using the model in order to realise the full potential and implications of the experimental findings
of this study and others.Thesis (PhD)--University of Pretoria, 2012.
gm2014
Plant Production and Soil Science
unrestricted