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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.
291

Cooperação e conflito nas águas da Bacia do Rio Paraíba do Sul: limites e possibilidades de gestão integrada no \'trecho paulista\" / Integrated Water Resource Management System in the Paraiba do Sul River Basin.

Ricardo Carneiro Novaes 21 August 2006 (has links)
Esta Tese analisa os condicionantes, os limites e as possibilidades postos à efetivação de uma gestão efetivamente integrada em bacias hidrográficas de dupla dominialidade, contextualizando tais questões ao modelo de gestão em implantação no Brasil a partir do início da década de 90. O trabalho está focado na gestão das águas da bacia do Rio Paraíba do Sul, analisando o processo histórico de construção do sistema e seus impactos nas estratégias de convivência entre os dois diferentes organismos atuantes no trecho paulista da bacia: o Comitê da Bacia Hidrográfica do Rio Paraíba do Sul (CBH-PS), responsável especificamente pela gestão no trecho paulista da bacia; e o Comitê para a Integração da Bacia do Rio Paraíba do Sul (CEIVAP), com jurisdição sobre a totalidade da bacia. O marco conceitual deste estudo apóia-se, principalmente, nas contribuições de autores situados no campo reconhecido como neoinstitucionalista. Promoveu-se um minucioso resgate do processo de implantação das diferentes “instituições políticas” relacionadas à gestão das águas da bacia, contextualizando assim o “processo político” de convivência entre os dois modelos de gestão retratados, abrindo-se dessa maneira perspectivas mais amplas para a análise dos conteúdos e dos impactos decorrentes dessas políticas. Para o adequado desenvolvimento deste estudo foi realizado o acompanhamento – tanto documental, quanto presencial - das atividades de ambos os Comitês. A pesquisa está também apoiada em entrevistas com um amplo conjunto de informantes centrais. O relato do histórico da gestão no trecho analisado foi organizado em cinco períodos, retratando movimentos de conflito e cooperação entre os atores. Apesar dos diversos desafios ainda a serem enfrentados rumo à integração, os dados coletados apontam para um gradual avanço na maturidade do sistema de gestão de recursos hídricos, com perspectivas positivas rumo à implantação de ações coordenadas e cooperativas na bacia. Esse movimento também explicita a dimensão temporal como um importante fator a ser considerado no processo de mudança institucional. / This study examines the possibilities and the restraints of the estabilishent an effective Integrated Water Resource Management System in the Paraiba do Sul River Basin in the context of the new Brasilian water management policy started in the 1990s. The research focused on the institutional an jurisdictional complexity of this management, particularly in the São Paulo State section. This study analyzes those institutional frameworks, their articulations and overlaps, and the outcomes on sustainable water use. The research was based on documental analysis and interviews. The management history report of the analyzed section was organized into 5 moments, depicting points of contention and cooperation among the ones involved. The gathered data point to a gradual improvement in the evolution of Integrated Water Resource Management System with positive perspectives towards the implementation of coordenated and cooperative actions in the Basin.
292

Otimização do uso da água no Perímetro Irrigado Formoso, utilizando a técnica da programação linear / Optimization of water use in Formoso Irrigation District using the technique of linear programming

Jorge Luis Copquer dos Santos Júnior 10 February 2011 (has links)
A otimização do uso da água é um desafio para os gerenciadores, pois o planejamento da irrigação requer cuidados especiais, a fim de compatibilizar o balanço hídrico com a demanda, tanto no que se refere à quantidade como a sua repartição espacial e temporal. Técnicas de otimização têm sido empregadas nas recentes décadas para tratar problemas de planejamento e manejo de sistemas de recursos hídricos. O objetivo do presente trabalho consistiu em propor planos ótimos de cultivos, utilizando modelos de programação linear que proporcionem a maximização do retorno líquido do Perímetro de Irrigação Formoso, especificamente quanto a área de lotes familiares. Os modelos utilizados neste estudo foram baseados nos dados que compõem os Relatórios de Monitoria Ano Agrícola de 2008 e 2009 da 2ª Superintendência Regional da CODEVASF, Relatório do Distrito de Irrigação do Projeto Formoso e em informações adicionais fornecidas pela referida empresa pública. O modelo estudado é uma formulação-padrão de programação linear, cuja função-objetivo consistiu em maximizar a receita líquida do projeto, utilizando-se as culturas mais cultivadas nessa área, sob regime de irrigação. Com base nas culturas consideradas e suas respectivas funções de resposta à água, nas restrições de área cultivada, nos preços e nos custos de produção, os resultados permitem as seguintes conclusões: A maximização da receita líquida no Perímetro Irrigado Formoso foi obtida com o modelo de lâminas alternativas, com um retorno financeiro de R$ 68.384.956,53, utilizando o seguinte padrão de cultivo: 30 ha de abóbora, 30 ha de feijão Phaseolus, 977 ha de melancia, 1868 ha de banana, 1200 ha de mamão e 300 ha de limão Tahiti, para o volume anual de 79.649.300 m3. Em qualquer nível de volume de água disponível os valores das lâminas de água foram maiores no modelo lâminas fixas do que no modelo lâminas alternativas. / The optimization of water use is a challenge for managers, because the planning of irrigation requires special care to reconcile the water balance with demand, both in terms of quantity as spatial and temporal distribution. Optimization technique have been employed in recent decades to address problems of planning and management of water resources systems. The aim of this study was to propose optimal crop plans, using linear programming models, providing the maximization of net return on Formoso Irrigation District, regarding the area of farming family. The models used in this study were based on data of the Reports Agricultural year 2008 and 2009 of the 2th Regional Superintendent of CODEVASF and additional information submitted by that government department. The studied model is a traditional linear programming formulation, in which the objective function consisted into maximizing the net income of the project using the most cultivated crops in the area, under irrigation conditions. Based on the crops considered and their response functions to water restrictions on acreage, prices and production costs, the results allow the following conclusions: the maximization of net revenue in Formoso Irrigation District was obtained with the model of alternative irrigation depths, with a payback of R $ 68,384,956.53, using the following crop pattern: 30 ha of squash, 30 ha of Phaseolus beans. 977 ha of watermelon, 1868 ha of banana, 1200 ha of papaya and 300 ha of Tahiti lime, for the annual volume of 79,649,300 m3. At any level of available water the irrigation depths in the model fixed was higher than the irrigation depths in the model alternatives.
293

The Role of Community Participation in Water Production and Management: Lessons From Sustainable Aid in Africa International Sponsored Water Schemes in Kisumu, Kenya

Ananga, Erick Oniango 14 October 2015 (has links)
Few studies have attempted to determine the tenability of Community Participation (CP) theory is explicating Water Production and Management dynamics in Urban Informal Settlements. Consequently, several gaps exist in knowledge of the value of this important theory for efforts to improve water service delivery in such settlements. The main purpose of this study is to contribute to efforts addressed to filling these gaps. Four water schemes established by Sustainable Aid in Africa International in partnership with different communities in the informal neighborhoods of Kisumu Kenya are used as empirical referent. The study is guided by the following three Research Questions; 1) what is the relationship between community participation and beneficiary satisfaction with the work of the water management committees in the four schemes? 2) what are the contributions (positive or negative) of community participation on the production of clean potable water supply in the informal settlements? 3) what are the participation-related factors affecting the performance of the schemes? Uncovering answers to these questions entailed the use of a mixed methods approach. The approach involved the application of both quantitative and qualitative techniques. The former was employed mainly to answer the first two Research Questions and latter to deal with Research Question Three. The quantitative component of data collection involved administering a survey questionnaire through a simple random sampling technique. Logistic Regression and Chi-square Tests were employed to analyze the quantitative data. In the qualitative phase, Focus Group Discussions, Observation, Transect Walks and Photographic evidence was used to collect data analyzed through Constant Comparison Analytic technique. For Research Question One, the logistic regression results indicate that five participatory variables are significantly associated with beneficiary satisfaction with the work of the water management committees. These are provision of paid or unpaid labor to the water schemes, household willingness to intervene against pipe vandalism, meeting attendance, willingness to contribute money or time to the community water scheme and whether a household has ever made a complaint about water supply/quality issues. For Research Question Two, the chi-square test shows that households who use community managed water schemes and attend water and sanitation meetings tend to practice better water handing hygiene in the settlements. For Research Question Three, the following factors are identified to be either aiding and/or impeding the success of the schemes; networking and collaboration, continuous community engagement/participation, the formation of water consumer groups, coordination and organizational management, extent of institutional formalization, provision of dividends to the community, clannism, population increase, and poverty and community fatigue. This dissertation sheds new light on the role played by CP in managing vital resources such as water in urban informal settlements/neighborhoods. An important policy contribution is that CP can be used as a viable strategy in the establishment of effective water schemes in urban informal settlements. Furthermore, it can act as an antidote with regards to water quality improvements in urban informal settlements/neighborhoods.
294

Modeling the Extent of Virus Removal in Waste Stabilization Ponds to Support Reuse of Wastewater

Vannoy, Kelly James 17 March 2016 (has links)
Waste stabilization ponds (WSPs) are one of the most prevalent types of domestic wastewater treatment technologies employed worldwide, and global stressors such as urbanization, population growth, climate change, and water scarcity have increased the demand for reusing treated wastewater. The safe reuse of treated wastewater in agriculture can ease water scarcity, aid in food production, and reduce environmental degradation from the discharge of wastewater effluent to surface waters. The ability to predict virus concentrations in wastewater effluent is an important criterion for determining whether wastewater is suitable for discharge to the environment or for reuse in agriculture. However, many uncertainties remain about virus removal efficiency in WSPs and there is currently no mechanistic or empirical model that reliably predicts virus removal in WSPs. The overall objective of this thesis research was to model the extent of virus removal in individual waste stabilization ponds to support the reuse of wastewater. A literature review was used to create a database of estimated apparent virus removal rate coefficients (Kv,app) in three different WSP types (anaerobic, facultative, and maturation ponds). The database consisted of 249 paired influent and effluent concentrations of enteric viruses or bacteriophages from 44 unique WSP systems, comprised of 112 individual WSPs from 19 different countries. Apparent virus removal rate coefficients (Kv,app) were calculated for each individual WSP using the following three mathematical models from reactor theory: complete mix, plug flow, and dispersed flow. Pearson’s correlation analysis was used to determine correlations between Kv,app values and the following design, operational, and environmental parameters: solar radiation, air temperature, pond depth, hydraulic retention time (HRT), and virus loading rates. The median Kv,app values were greater for anaerobic ponds than for facultative and maturation ponds; however, Kv,app values in facultative and maturation ponds had more significant correlations with design, operational, and environmental parameters. Additionally, Kv,app values appear to be significantly different for various types of enteric viruses and bacteriophages. Alternative multiple linear regression equations were developed to predict Kv,app values using the design, operational, and environmental parameters as explanatory variables. Analysis of variance (ANOVA) tests were used to select the most appropriate multiple linear regression equations with the least amount of explanatory variables. The most appropriate plug flow and dispersed flow multiple linear regression equations for predicting Kv,app values included air temperature and HRT as explanatory variables. The results indicate that the plug flow regression equation was able to better predict Kv,app values (R2 = 0.38) than the dispersed flow regression equation (R2 = 0.24) in facultative and maturation ponds based on the dataset. However, both the dispersed flow and plug flow models had R2 values of approximately 0.84 when they were used to predict effluent virus concentrations in facultative and maturation ponds based on the dataset. According to this research, the plug flow regression equation is recommended for predicting apparent virus removal rate coefficients in WSPs. However, a multi-model approach that utilizes both the plug flow and dispersed flow models may yield a more robust mathematical model that can improve WSP design, reliably predict virus removal in WSPs, and ultimately be used to support wastewater reuse.
295

The Ability of an Aquatic Invader to Uptake Nutrients in an Upstream Estuarine Environment: Implications for Reducing the Intensity and Frequency of Massive Fish Kills in Florida

Kerr, Melissa L. 25 May 2017 (has links)
The purpose of this study was to assess whether nutrient absorption rates by water hyacinths are affected by low-salinity levels. In a controlled experiment, water hyacinths demonstrated the ability to absorb a significant amount of nutrients in low-saline waters while maintaining a slowed growth rate and shortened life span. Nutrient rates were reduced by an average of 36% in ammonia nitrogen and 48% in reactive phosphorus in the tanks of 4.45 parts per thousand (ppt) salinity. Growth rate in the experimental tanks of 4.45 ppt was observed at 33% slower than that of the control. The high salinity comparison tank of 7.0 ppt experienced complete mortality after three days. Phytoremediation practices through the use of an aquatic invader, water hyacinths, can be used to reduce large-scale fish kills along the eastern U.S.’s major estuarine systems, focusing on Florida’s waters. Toxic dinoflagellates and other harmful algal blooms have been plaguing the contributing waterways of North Carolina and the Chesapeake Bay and are the main causes of these massive fish kills. The characteristics and trends that these upstream estuarine systems are following could serve as a warning for Florida. An analysis of Florida’s fish kill database, as well as patterns and trends of the fish kills in North Carolina and the Chesapeake Bay, were used to determine areas at an increased risk for toxic dinoflagellates and harmful algal blooms to occur. Areas are proposed for water hyacinths to be implemented in a controlled method to reduce massive fish kills in Florida’s waters.
296

Quantifying and Modeling Surface Inflow and Groundwater Infiltration into Sanitary Sewers in Southern Pinellas County, FL

Long, Megan E. 20 June 2017 (has links)
Following large rain events, excess flow in sanitary sewers from inflow and infiltration (I/I) cause sanitary sewer overflows (SSO), resulting in significant problems for Pinellas County and the Tampa Bay area. Stormwater enters the sanitary sewers as inflow from improper or illegal surface connections, and groundwater enters the system as infiltration through cracks in subsurface infrastructure. This pilot study was designed to develop methods to separate and quantify the components of I/I and to build a predictive model using flowmeter and rainfall data. To identify surface inflow, daily wastewater production and groundwater infiltration patterns were filtered from the flow data, leaving a residual signal of random variation and possible inflow. The groundwater infiltration (as base infiltration, BI) was calculated using the Stevens-Schutzbach method, and daily wastewater flow curves were generated from dry weather flow (DWF) data. Filtered DWF values were used to construct a range of expected residuals, encompassing 95% of the variability inherent in the system. Filtered wet weather flows were compared to this range, and values above the range were considered significant, indicating the presence of surface inflow. At all 3 flow meters in the pilot study site, no surface inflow was detected, and the I/I was attributed to groundwater infiltration (as BI). Flow data from 2 smaller sub-sewersheds within the greater sewershed allowed analysis of the spatial variability in BI and provided a method to focus in on the most problematic areas. In the sub-sewershed with the shallowest water table and most submerged sanitary sewer infrastructure, an average of 56% of the average daily flow consisted of groundwater, compared to 44% for the entire study site. Cross-correlation analysis suggests that rain impacts the water table for up to 9 days, with the highest impact 1 to 3 days after rain events, and the water table, in turn, impacts infiltration for up to 6 days. The highest correlation between rainfall and infiltration occurs 3 to 5 days after a rain event, which corroborates observations from Pinellas County that severe flows to the reclamation facility continue for 3 to 5 days after severe storms. These results were used to build a linear regression model to predict base infiltration (per mile of pipeline) during the wet season using the previous 7 days of daily rainfall depths. The model tended to under-predict infiltration response to large storm events with a R2 value of 0.52 and standard error of regression of 5.3. The results of the study show that inflow can be detected using simple time series analysis instead of traditional smoke and dye testing. In this study site, however, groundwater infiltration is the only significant source of I/I. Additionally, water table and sewer invert elevations serve as useful indicators of potential sites of groundwater infiltration. Infiltration can be modeled as a function of the previous 7 days of rainfall, however simple linear regression cannot fully capture the complexity of the system response.
297

Environmental and Community Health in South San Diego County: A Behavior Analysis of Recreational Ocean Users Along Imperial Beach, California

Brophy, Trista 28 June 2016 (has links)
Garbage & sewage runoff into the Pacific Ocean at the shoreline along the U.S./Mexico Border region poses serious health and environmental threats. The purpose of this study was to analyze the current beach users’ behavioral factors that may be linked to illness prevalence from Coronado Island to the U.S./Mexico border at Imperial Beach in San Diego County. It is a continuation of a study completed by Wildcoast and Imperial Beach Clinic in 2011. The study tried to answer the following two major questions: How have the number of illnesses reported by users along South San Diego County beaches changed in the last 5 years? What relationships exist between reported illness and beach user behavior, if any? To accomplish this, a 2-page self-reporting survey was administered asking about demographics, beach recreation habits, illness and exposure information, and allowed for comments. Surveys were distributed to beach users along Imperial Beach northward to Coronado Island during May, June, and July of 2014. Quantitative as well as qualitative data were collected. The results show that the majority of respondents did not report suffering from an illness, however, for those who did report an illness, frequency of water entry, seasonality of water entry, entry during beach closures, and primary means of water contact were significantly correlated to illness prevalence.
298

Analysis of Managerial Decision-Making within Florida’s Total Maximum Daily Load Program

Barthle, Justin 31 October 2016 (has links)
Water quality has evolved legislatively from protection of navigation routes and quantity of sources to more emphasis on impairments on water quality for surface and groundwater sources. Nonpoint or diffuse sources of impairments represents a major challenge for management due to the complexity of its sources and difficulty in tracking. The most cited sections on public policy analysis focuses on the overall process agencies employ to understand the results the program yields. Often overlooked are finer details and mechanisms, such as decision-making and priority setting, which have a great impact on the overall process. To investigate these factors, we need to analyze the decision-making process used by managers. This study focuses on using information from those with direct involvement in the establishment and implementation of the Total Maximum Daily Load program for the state of Florida. This study used decision-making analysis models from Rational-Decision-Making and Multi-Criteria Decision Analysis concepts to construct questionnaires that looks to develop priorities as seen by managers’ preferences for several presented options. This methodology allowed us to structure the viewpoints and processes water quality managers use to breakdown decisions. The analyzed results show water quality managers prefer strong management options, involvement from stakeholders with scientific knowledge, and data collected from the source or point of impact. Interestingly, opinions in the group show that urban best management practices are considered more effective than their agriculture counterparts with a disfavor for volunteer derived data. Ultimately, the survey highlights the need for more robust enforcement and reliable measurement of non-point source of impairments. Continued public outreach and education, especially through workshops, are denoted as important tasks to completing successful TMDLs and should be expanded and strengthened by both the Florida Department of Environmental Protection and its boundary programs.
299

Impact of Sludge Layer Geometry on the Hydraulic Performance of a Waste Stabilization Pond

Ouedraogo, Faissal Romaric 28 June 2016 (has links)
Improving the hydraulic performance of waste stabilization ponds (WSPs) is an important management strategy to not only ensure protection of public health and the environment, but also to maximize the potential reuse of valuable resources found in the treated effluent. To reuse effluent from WSPs, a better understanding of the factors that impact the hydraulic performance of the system is needed. One major factor determining the hydraulic performance of a WSP is sludge accumulation, which alters the volume of the pond. In this study, computational fluid dynamics (CFD) analysis was applied to investigate the impact of sludge layer geometry on hydraulic performance of a facultative pond, typically used in many small communities throughout the developing world. Four waste stabilization pond cases with different sludge volumes and distributions were investigated. Results indicate that sludge distribution and volume have a significant impact on wastewater treatment efficiency and capacity. Although treatment capacity is reduced with accumulation of sludge, the latter may induce a baffling effect which causes the flow to behave closer to that of plug flow reactor and thus increase treatment efficiency. In addition to sludge accumulation and distribution, the impact of water surface level is also investigated through two additional cases. Findings show that an increase in water level while keeping a constant flow rate can result in a significant decrease in the hydraulic performance by reducing the sludge baffling effect, suggesting a careful monitoring of sludge accumulation and water surface level in WSP systems.
300

Vergers plurispécifiques : piloter l’enracinement des arbres en profondeur par l’association d’herbacées dès la plantation / Plurispecific orchards : shape in depth trees root system by association herbaceous crops at plantation

Forey, Oswaldo 13 December 2016 (has links)
L'agroforesterie consiste à mélanger sur la même surface des arbres et des cultures et nécessite que des relations de complémentarité s'établissent entre les deux espèces pour diminuer la compétition pour les ressources, notamment au niveau des interactions racinaires. L'objectif du travail de cette thèse était de tester et d'évaluer la possibilité de piloter l'enracinement de jeunes pêchers sous les racines de la culture associée (enherbement) afin d'établir une complémentarité dans l'utilisation des ressources du sol et en utilisant deux leviers: (i) un déficit hydrique modéré pour changer le patron d'allocation du carbone entre les compartiments aérien et souterrain en faveur des racines et (ii) la compétition interspécifique pour l'eau pour exclure les racines de l'arbre des horizons de sol superficiels et le contraindre à pousser en profondeur. Pour cela, un verger de pêchers composé de trois traitements (témoin bien irrigué, déficit modéré, déficit modéré + enherbement) a été installé en janvier 2013 et suivi pendant deux ans. La croissance du compartiment aérien a été suivie de manière dynamique sur la saison de croissance et des excavations racinaires ont été effectuées chaque année à la fin de la saison de croissance. Nos résultats montrent que tous les composants de la croissance ont été significativement réduit par le déficit hydrique très modéré. La combinaison d'un déficit hydrique modéré et d'un enherbement total ont réduit par quatre la taille des arbres au bout de deux années de croissance, réduction causée par deux mécanismes probablement additifs: (i) la compétition de l'herbe pour l'espace, réduisant le volume de sol prospectable par les racines de l'arbre et par répercussion le volume de l'appareil aérien et (ii) la compétition de l'herbe pour l'eau, qui en créant un dessèchement du sol, amène probablement le pêcher à générer des signaux racinaires à destination des parties aériennes pour réduire la transpiration par fermeture des stomates. Nos résultats sur les racines montrent que le développement du système racinaire du pêcher dans les conditions de notre étude pendant les deux premières années après la plantation est essentiellement plagiotrope. Le rapport racines/branches n'a pas été significativement modifié en faveur des racines sous l'effet du déficit hydrique mais la combinaison du déficit hydrique et de la compétition avec l'enherbement a diminué par trois la biomasse racinaire des arbres et exclu totalement les racines de l'horizon de surface (0-10 cm) au bout de deux ans. Cependant, la croissance racinaire se concentre majoritairement dans les 30 premiers cm de sol pour tous les traitements, mais une faible proportion du système racinaire totale (5%) des pêchers en condition hydrique non limitante dépasse les 70 premiers cm de sol (profondeur d'excavation maximale de l'étude) et est capable de prélever de l'eau jusqu'à 2 m de profondeur. Ainsi, nos résultats amène à penser que la séparation des systèmes racinaires entre l'arbre et la culture est très certainement une propriété émergente pilotable, à conditions de caractériser l'architecture racinaire de l'arbre et notamment sa plasticité chez des arbres jeunes. Des pratiques innovantes telles que l'installation des arbres par semis puis greffage au champ de la variété de production pourraient permettre de s'affranchir des traumatismes racinaires inhérents au mode de production des plants en pépinière. Il est également possible de moduler l'effet de la culture associée en sélectionnant des espèces et variétés dont la capacité compétitive souterraine est adaptée au stade de développement de l'arbre, en associant par exemple des espèces à faible capacité compétitive au début de son développement et à capacité compétitive graduellement plus importante au fur et à mesure qu'il grandit. / Agroforestry consists of association trees and crop in the same plot and requires that complementarity relationships be established between the two species in order to reduce competition, especially at the root level. The aim of this work was to test and evaluate the possibility of driving young peach tree roots under the roots of the associated crop (grass) in order to establish complementarity in resources uptake using two levers: (i) e moderate water deficit to change the carbon allocation pattern between shoots and roots in favour of roots and (ii) interspecific water competition to exclude tree roots from the first soil horizons and force them to grow at depth. To do so, we planted in January 2013 a peach tree orchard composed of three treatments (well-watered control, moderate water deficit and moderate water deficit + grass groundcover) which was monitored for two years. Shoot growth was dynamically monitored over the growing season and root excavations were performed each year at the end of the growing season. Our results show that all components of aerial growth were significantly reduced by the very moderate water deficit applied. The combination of a moderate water deficit and a grass groundcover led to a fourfold reduction in tree size after two years due to (i) grass competition for space, which reduced soil volume for the tree roots and consequently reduced shoot size and (ii) grass competition for water which by drying the soil led the tree to send root to shoot signals in order to reduce transpiration by stomatal closure. Our results on roots show that peach tree roots in the first two years of growth are mainly plagiotropic in the conditions of our study. The root/shoot ratio was not significantly modified in favour of roots under a moderate water deficit but combination of water deficit with grass competition led to a threefold reduction in root biomass et excluded tree roots from the topsoil horizon (0-10 cm) after two years. However, root growth mainly concentrated in the first 30 cm of soil in all treatments, but a small fraction of the root system (5%) in the control treatment was growing below the first 70 cm of soil (maximal excavation depth in our study) and was able to take up water up to 2 m depth. Thus, our results suggest that root system separation between trees and crop is a manageable emerging property, given that tree root architecture is characterized, and especially its plasticity in young trees. Innovating practices such as sowing trees and grafting them in the field could alleviate root injuries inherent to nursery practices. It is also possible to adjust the effect of the associated crop by selecting species and cultivars whose competitive ability is adapted to the tree age, by associating species with low competitive ability at the beginning of the tree development and with gradually more important competitive ability as the tree ages.

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