Stormwater detention basins are commonly used in the Eastern United States to temporarily store and attenuate stormwater runoff, and also serve as habitats for native and exotic plants. However, during winter, these basins receive saline runoff from road salt application, which contributes to Freshwater Salinization Syndrome (FSS). Since limited research has connected direct measurement of soil and stormwater salinities to biodiversity and phytoremediation potential of salt-tolerant plant species, this thesis aimed to fill this gap. We selected a set of detention basins draining mostly pervious areas, parking lots, or roads in Northern Virginia and measured temporal variations in stormwater and soil salinities, depth profiles of soil salinities, plant community composition, and plant tissue ion concentration. The results indicated elevated levels of sodium, chloride, electrical conductivity (EC), and exchangeable sodium percentage (ESP)/sodium adsorption ratio (SAR) in soil and stormwater after road salt application during winter, followed by a decrease during the growing season for basins draining parking lots and roads. A subsequent increase at the end of the season was observed for all site types. While some stormwater samples exceeded toxicity thresholds, most soil samples did not exceed their respective thresholds nor reach saline or sodic conditions, and native and exotic plant species of both salt-sensitive and salt-tolerant classifications were observed at almost all sites, although proportions of each varied by site type. Tissue analysis of select plants revealed ionic concentrations that generally coincided with observed soil and stormwater concentrations at each major site type. These findings have implications for future detention basin planting regimes to mitigate FSS, and the thesis discusses native plants found to provide the most benefit for phytoremediation. / Master of Science / Stormwater detention basins are commonly used in the Eastern United States. They slowly release stormwater runoff and serve as habitats for native and exotic plants. However, during winter, these basins receive saline runoff from road salt application. This contributes to Freshwater Salinization Syndrome (FSS). Limited research has connected direct measurement of soil and stormwater salinities to biodiversity and plants' ability to uptake salts, so this thesis aimed to fill this gap. A set of detention basins draining mostly pervious areas, parking lots, or roads in Northern Virginia were selected. Next, stormwater and soil salinities over time, depth profiles of soil salinities, plant community composition, and plant tissue ion concentration were measured. The results showed higher levels of standard salinity benchmarks in soil and stormwater after road salt application during winter, followed by a decrease during the growing season for parking lot and road sites. A final increase in the fall was observed for all site types. While some stormwater samples were toxic to plants, most soil samples were not toxic, saline, or sodic. Also, native and exotic plant species of both salt-sensitive and salt-tolerant classifications were observed at almost all sites, but proportions of each varied by site type. Plant tissues contained ionic concentrations that reflected observed soil and stormwater concentrations at each site type. These findings can inform future detention basin planting regimes to mitigate FSS. The thesis also discusses native plants that provide benefits for phytoremediation.

Thesis (MScAgric (Agronomy)--University of Stellenbosch, 2007. / Soil salinity is a serious constrain to crop production in many countries. In the Western Cape canola production area, large variability in soil properties within the same field is a very common feature. Some of this variability may be ascribed to differences in salinity. These saline patches affected the germination and survival of cereal crops like wheat and may therefore also be a reason for the high variability and generally low canola yields obtained in this area. It will therefore be important to quantify the effect of such saline conditions on the germination and seedling establishment of canola in an effort to improve yields. In this study several experiments were conducted under controlled conditions in either Petri dishes in an incubator or pots in a temperature controlled glasshouse to determine the salinity response of canola. Results of the experiments done in Petri dishes, showed that the germination response of canola (Brassica napus L., cv. Tornado) to increasing levels of salinity is very similar to that of wheat (Triticum aestivum L., cv SST 88). Although canola germinated more rapidly than wheat at a temperature of 20 ºC, the final percentage germination for both crops decreased severely when NaCl induced salinity exceeded levels of an EC of 8 dS m-1, but less severe responses were obtained with NaCl/CaCl2 induced salinity. Under soil conditions an interaction between soil type and salinity level showed that the responses in sandy soil to an increase in salinity from 0 to 8 iv dS m-1 were less severe than in loamy soil and especially when salinity stress was induced by NaCl. Although cultivar Spektrum showed more tolerance to saline conditions during the germination and seedling stages in pot experiments when compared to other cultivars tested, these results will have to be confirmed in field trails where grain yield and quality can be measured.

Thesis (MScEng (Civil Engineering))--Stellenbosch University, 2008. / In recent years, concern about the water quality in the Berg River received a fair degree of attention, particularly with the imminent construction of the Berg Water Project (BWP). Particular concerns have been expressed about the water quality with respect to total dissolved salts (TDS) at Misverstand Dam. In previous studies (Fourie and Görgens, 1977) it was identified that the saline water was mostly generated in the lower portion of the Berg River Catchment (Matjies, Moorreesburg and Sandspruit Rivers) and that the abstraction of acceptable quality water higher up in the Berg River could possibly result in salinity problems at Misverstand Dam. Contrary to expectation, these studies also showed that for the most saline catchments, a winter peak in TDS concentrations also existed. To help address these concerns, a Water Research Commission (WRC) project was initiated in 2003 in which the newly-developed salinity module of the daily Agricultural Catchment Research Unit (ACRU) agrohydrological model, known as ACRUSalinity, would be configured for the Berg River Catchment. This model had previously been configured and calibrated for the Mkhomazi Catchment (Teweldebrhan, 2003) which exhibited relatively low streamflow TDS concentrations (100 mg/l) and it was deemed necessary to ascertain whether comparable TDS values could be simulated in the Berg River Catchment, where TDS concentration could rise to well above 1 000 mg/l in certain tributaries. In this project, ACRUSalinity was configured for the Berg River Catchment on a distributed basis, aiming to capture the spatial distribution of rainfall and geophysical characteristics which inherently exist in a catchment as expansive as the Berg. Initial application of the "Beta version" of ACRUSalinity to the Berg River Catchment revealed that it failed to produce simulated TDS values which were representative of the observed data. It became evident that the model required both additional salinity-related functions and modifications of existing functions. After the implementation of these algorithm changes the correspondence of simulated and observed TDS concentrations improved markedly. Verification of the ACRUSalinity simulated flows and calibration of the salinity-related parameters was based on the values of predefined objective functions. Reasonably representative flows could be obtained provided that the catchment discretisation and driver rainfall selection process were adequate. Salinity related parameters were determined purely on an iterative basis, although a priori estimation of these parameters was possible. Preliminary interdependency tests of these parameters revealed that the final calibrated set of salinity-related parameters was probably not unique and that some a priori decision making would be required when selecting the most realistic set of parameters. Quantification of the potential effect of the Berg River Dam on the TDS concentrations at Misverstand Dam was achieved as follows: the ACRUSalinity model was verified for flow and calibrated for TDS at available and reliable flow gauging stations. This was then followed by a long-term simulation run which yielded daily TDS time series for comparison, on an exceedance basis, with the observed record. Since the concern about the possible deterioration of water quality at Misverstand Dam was only a winter concern (May to September), comparisons were only drawn over this period. The flow-routing option in ACRUSalinity was not activated and a 1:1 daily comparison of flows and TDS concentrations, based on values of the objective function, was thus not possible. Results from this study showed that even with a daily model, the exceedance percentages of the TDS concentrations after the construction of the Berg River Dam were comparable with the exceedance percentages obtained from the original monthly modelling study (DWAF, 1993). In this study, however, it was possible to capture the increasing TDS concentration which was evident over winter months in the observed data record for the Matjies River and Sandspruit River catchments. The testing of the model’s effectiveness in the evaluation of engineering options was accomplished as follows: several options for ameliorating the possible deterioration of water quality at Misverstand Dam were defined, based on its practicality and cost of implementation. For example, the Withoogte water treatment works abstracts water from Misverstand Dam for supply to the West Coast region when water quality is acceptable (i.e. a TDS lower than 450 mg/l). It was proposed that to minimise the effect of periods when no abstraction from Misverstand could occur due to unacceptable water quality, a second reservoir at the treatment works should be lined and used to provide bridging storage for water from Misverstand Dam when the water quality was acceptable. The calibrated ACRUSalinity model was then modified to reflect the physical attributes of this engineering scenario of interest to produce sets of flow and TDS time series which could be further analysed to determine assurance of supply, in terms of predetermined TDS concentration thresholds in Misverstand Dam. Using this particular engineering option, the analysis revealed that a 300 mg/l TDS upper-limit at Misverstand was too stringent and that 450 mg/l was probably more realistic.

The feasibility of predicting porewater salinity based on calibrated surface electromagnetic methods is discussed in a coastal wetland on the southern banks of Tampa Bay in West-Central Florida. This study utilizes a new method to float commercial land based electromagnetic (EM) instruments in shallow marine waters of less than 1.5 meters. The floating EM-31 (Geonics, Ltd.) effectively sensed the magnitude and lateral extent of high and low salinity porewaters within mangrove lined ditches and ponds. Resistivity and EM geophysical methods are merged with direct sampling data to calibrate layers in electromagnetic models to infer shallow (<30m) groundwater salinity patterns. Initial marine resistivity surveys are necessary to discriminate between equivalent EM model solutions for seafloor conductivities beneath shallow (0.1-1.5m) marine (~30 ppt) waters. Using formation factors computed from nearby resistivity surveys, porewater conductivity predictions based on surface EM-31 and EM-34 measurements are successful at distinguishing overall porewater salinity trends. At the Tampa Bay study site, the most distinctive terrain conductivity anomalies are associated with mangroves bordering marine waters. Highly elevated porewater conductivities are found within 5m of the mangrove trunks, falling sharply off within 10m, presumably due to saltwater exclusion by mangrove roots. Modeling indicates the shallow water EM-31 measurements probably lack the resolution necessary to image more subtle porewater conductivity variations, such as those expected in association with diffuse submarine groundwater discharge. However, the technique has potential application for locating high contrast zones of freshwater discharge and other salinity anomalies in shallow and nearshore areas not accessible to conventional marine resistivity or land-based arrays, and hence may be useful for interdisciplinary studies of coastal wetland ecosystems.

"January 14, 2004" Includes bibliographical references (leaves 201-213)

The movement of a fluid and solute through a porous medium is of great practical interest because this describes the spread of contaminants through an aquifer. Many contaminants occur at concentrations sufficient to alter the density of the fluid, in which case the physics is typically modelled mathematically by a pair of coupled, nonlinear partial differential equations. There is disagreement as to the exact form of these governing equations. Codes aiming to solve some version of the governing equations are typically tested against the Henry and Elder benchmark problems. Neither benchmark has an analytic solution, so in practice they are treated as exercises in inter code comparison. Different code developers define the boundary conditions of the Henry problem differently, and the Elder problems results are poorly understood. The Henry, Elder and some other problems are simulated on several different codes, which produce widely-varying results. The existing benchmarks are unable to distinguish which code, if any, simulates the problems correctly, illustrating the benchmarks' limitations. To determine whether these discrepancies might be due to numerical error, one popular code, SUTRA, is considered in detail. A numerical analysis of a special case reveals that SUTRA is numerically dispersive. This is confirmed using the Gauss pulse test, a benchmark that does have an analytic solution. To further explain inter code discrepancies, a testcode is developed which allows a choice of numerical methods. Some of the methods are based on SUTRA's while others are finite difference methods of varying levels of accuracy. Simulations of the Elder problem reveal that the benchmark is extremely sensitive to the choice of solution method: qualitative differences are seen in the flow patterns. Finally, the impact of numerical error on a real-world application, the simulation of saline disposals, is considered. Saline disposal basins are used to store saline water away from rivers and agricultural land in parts of Australia. Existing models of disposal basins are assessed in terms of their resemblance to real fieldsite conditions, and in terms of numerical error. This leads to the development of a new model which aims to combine verisimilitude with numerical accuracy. / Thesis (Ph.D.)--School of Mathematical Sciences (Applied Mathematics), 2004.

Non-dilute salt strength solutions occur in many near surface geologic environments. In order to better understand the occurrence and movement of the water and salt, mathematical models for this non-ideal fluid need to be developed. Initial boundary value problems may then be solved to predict behavior for comparison with observations. Using the principles of equilibrium reversible and irreversible thermodynamics, relationships describing the thermo-physics of non-dilute saline solutions in variably saturated porous media are investigated. Each of four central chapters investigates a particular aspect of the flow of saline solutions through porous media. The first chapter derives the general relationships describing the effects of salt on the vapor content in the gas phase and also on the liquid pressure. The second chapter summarizes an example using the new theory for sodium chloride (NaCl) from zero to saturated strength. Additional terms beyond the dilute approximation are shown to be more important in very dry, fine textured soils with significant salt content. The third chapter derives the salt corrections for Darcy-type flow laws for variably saturated porous media, and an example for NaCl is given. Agreement between theory and experimental data is good, though there appear to be some unaccounted for effects. These effects may be the result of ionic interaction of the salt with the loamy sand used, and/or the effect of hysteresis of the water content-pressure relationship. The final chapter investigates two fundamental assumptions commonly used in process thermodynamics when considering mixtures described by porous media, saline water, and moist air. The first assumption is that temperature is the generalized intensive variable associated with entropy. The second assumption is that the form of the differential of total energy is known a-priori. It is shown that the first assumption is suspect under some circumstances, and a generalized notion of how to select extensive variables for a given system is introduced for comparison with the second assumption. Examples comparing the "usual" and new theories are accomplished for ideal gases and for isotropic Newtonian liquids, with results being favorable except possibly for the Gibbs-Duhem Relation of the Newtonian liquid for the "usual" theory. / Graduation date: 2005

[Truncated abstract] The salinisation of agricultural land, urban infrastructure and natural habitat is a serious and increasing problem in southern Australia. Government funding has been allocated to the problem to attempt to reduce substantial costs associated with degradation of agricultural and non-agricultural assets. Nevertheless, Government funding has been small relative to the size of the problem and therefore expenditure needs to be carefully targeted to interventions that will achieve the greatest net benefits. For intervention to be justified, the level of salinity resulting from private landholder decisions must exceed the level that is optimal from the point of view of society as a whole, and the costs of government intervention must be less than the benefits gained by society. This study aims to identify situations when government intervention is justified to manage dryland salinity that threatens to affect road infrastructure (a public asset). A key gap in the environmental economics literature is research that considers dryland salinity as a pollution that has off-site impacts on public assets. This research developed two hydrological/economic models to achieve this objective. The first was a simple economic model representing external costs from dryland salinity. This model was used to identify those variables that have the biggest impact on the net-benefits possible from government intervention. The second model was a combined hydro/economic model that represents the external costs from dryland salinity on road infrastructure. The hydrological component of the model applied the method of metamodelling to simplify a complex, simulation model to equations that could be easily included in the economic model. The key variables that have the biggest impact on net-benefits of dryland salinity mitigation were the value of the off-site asset and the time lag before the onset of dryland salinity in the absence of intervention. ... In the case study of dryland salinity management in the Date Creek subcatchment of Western Australia, the economics of vegetation-based and engineering strategies were investigated for road infrastructure. In general, the engineering strategies were more economically beneficial than vegetation-based strategies. In the case-study catchment, the cost of dryland salinity affecting roads was low relative to the cost to agricultural land. Nevertheless, some additional change in land management to reduce impacts on roads (beyond the changes justified by agricultural land alone) was found to be optimal in some cases. Reinforcing the results from the simple model, a key factor influencing the economics of dryland salinity management was the urgency of the problem. If costs from dryland salinity were not expected to occur until 30 years or more, the optimal response in the short-term was to do nothing. Overall, the study highlights the need for governments to undertake comprehensive and case-specific analysis before committing resources to the management of dryland salinity affecting roads. There were many scenarios in the modelling analysis where the benefits of interventions would not be sufficient to justify action.

Made available in DSpace on 2016-08-31T13:24:18Z (GMT). No. of bitstreams: 1 RozanaMSL_DISSERT.pdf: 880698 bytes, checksum: 1ba1c30a496b8eed63416cd7e399a20d (MD5) Previous issue date: 2013-10-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The increased demand for water for irrigation has led farmers to use water with higher salinity, and its use is subject to the crop tolerance to salinity and irrigation management . The nitrogen has provided a significant increase in production saline environment and reduces the effect of the salts . This work aimed to study the effects of different levels of salinity of irrigation water and nitrogen applied through fertigation in evapotranspiration and yield of pumpkin, the climatic conditions of the region of Mossoró - RN. An experiment in field conditions at the Experimental Farm UFERSA, Mossoró, RN was developed. The treatments consisted of irrigation application with five salinity levels (S1 = 0.5, S2 = 1.5, S3 = 2.5, S4 = S5 = 3.5 and 4.5 dS m- 1) and three Nitrogen doses ( 30 , 100 , 170 % of the recommended dose) . To estimate the ETo Penman - Monteith equation parameterized by FAO was used. The meteorological data required for estimating ETo were collected by an automatic weather station, installed in the experimental area. The ETc was measured by four weighing lysimeters installed in salinity levels S1 and S5. The nutritional status of plants was evaluated by foliar analysis of the flowering period. Periodic reviews of the evolution of soil salinity were performed using soil samples throughout the crop cycle. The results showed that ECT decreased between the irrigation water S1 and S5, where during the entire evaporation cycle was 300.29 and 279.20 mm, respectively. As for the mean values Kc's the phenological stages I, II, III, IV, 0.42 , 0.68 , 1.08, 0.78 for the S1 treatment and 0.41 , 0.62 , 0.92, 0.60 for the S5 treatment , showing that the obtained for Kc's were always higher than those obtained for Kc's S5 level S1 level . There was a significant effect of nitrogen on the yield components, except for the average mass of total and marketable fruit. The total and marketable yield of fruits were significantly affected by the quality of the irrigation water and by nitrogen rates / A maior demanda por água para irrigação tem levado os agricultores a utilizarem águas com salinidade mais elevada, sendo que sua utilização fica condicionada à tolerância das culturas à salinidade e ao manejo da irrigação. A adubação nitrogenada tem proporcionado um aumento significativo na produção e em ambiente salino reduz o efeito dos sais. Este trabalho teve como objetivo estudar os efeitos de diferentes níveis de salinidade da água de irrigação e de doses de nitrogênio aplicado via fertirrigação na evapotranspiração e na produção da abóbora, nas condições climáticas da região de Mossoró-RN. Foi desenvolvido um experimento em condições de campo, na Fazenda Experimental da UFERSA, Mossoró, RN. Os tratamentos foram compostos da aplicação de irrigação com cinco níveis de salinidade (S1=0,5; S2=1,5; S3=2,5; S4=3,5 e S5=4,5 dS m-1) e três doses de Nitrogênio (30, 100, 170 % da dose recomendada). Para estimativa da ETo foi utilizada a equação de Penman-Monteith parametrizada pela FAO. Os dados meteorológicos necessários para a estimativa da ETo foram coletados por uma estação meteorológica automática, instalada na área experimental. A ETc foi medida por quatro lisímetros de pesagem, instalados nos níveis de salinidade S1 e S5. O estado nutricional das plantas foi avaliado pela análise foliar no período de floração. Foram realizadas avaliações periódicas da evolução da salinidade do solo, usando amostras de solo ao longo do ciclo da cultura. Os resultados mostraram que a ETc diminuiu entre a água de irrigação S1 e S5, onde a evapotranspiração total durante o ciclo foi de 300,29 e 279,20 mm, respectivamente. Quanto aos Kc s verificaram-se os valores médios nos estádios fenológicos I, II, III e IV de 0,42, 0,68, 1,08, 0,78 para o tratamento S1 e 0,41, 0,62, 0,92, 0,60 para o tratamento S5, mostrando que os Kc s obtidos para o nível S1 foram sempre maiores que os Kc s obtidos para o nível S5. Houve efeito significativo do nitrogênio sobre os componentes de produção, exceto para a massa media dos frutos totais e comerciais. A produtividade total e a comercial de frutos foram significativamente afetados pela qualidade da água de irrigação e pelas doses de nitrogênio

SILVA, Alexandre Reuber Almeida da Silva. Respostas e adaptações de plantas de coqueiro "anão verde" ás interações entre deficiência hídrica e salinidade do solo. 2015. 237 f. : Tese (doutorado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Engenharia Agrícola, Programa de Pós-Graduação em Engenharia Agrícola, Fortaleza-CE, 2015. / Submitted by demia Maia (demiamlm@gmail.com) on 2016-07-08T15:25:35Z No. of bitstreams: 1 2015_tese_arasilva.pdf: 4598302 bytes, checksum: dc76917acc87d1d0031e4e0c50eced01 (MD5) / Approved for entry into archive by demia Maia (demiamlm@gmail.com) on 2016-07-08T15:25:55Z (GMT) No. of bitstreams: 1 2015_tese_arasilva.pdf: 4598302 bytes, checksum: dc76917acc87d1d0031e4e0c50eced01 (MD5) / Made available in DSpace on 2016-07-08T15:25:55Z (GMT). No. of bitstreams: 1 2015_tese_arasilva.pdf: 4598302 bytes, checksum: dc76917acc87d1d0031e4e0c50eced01 (MD5) Previous issue date: 2015 / In this work morphological, physiological, biochemical and nutritional responses, to elucidate the possible adaptive strategies of young coconut plants, cultivating "Green Dwarf", involved with tolerance to the effects of stress isolated and combined soil salinity and water stress. In the experiment, conducted in a greenhouse, the greenhouse type, in Fortaleza, Ceará, were evaluated under statistical design of randomized blocks in a split plot arrangement, the effects of different levels of water stress by imposing different percentages resets the potential evapotranspiration - ETpc (20; 40; 60; 80 and 100%), related to increasing levels of soil salinity (1.72, 6.25, 25.80 and 40.70 dS m-1) provided by soils derived from the Irrigated Perimeter Morada Nova - PIMN. The effects of treatments on plants were evaluated using the variables: plant height, leaf number, stem diameter, leaf area, biomass production (root, shoot and total), compared root dry biomass of aerial-1, to salinity tolerance indices, leaf gas exchange (stomatal conductance, transpiration, photosynthesis, instant and intrinsic efficiency of water use), quantum yield of chlorophyll fluorescence (Fv Fm-1) level for total chlorophyll (Spad index) , total content of chlorophyll (a + b) and carotenoids, leaf water potential, leaf and root levels of inorganic solutes (potassium ions, sodium and chloride) and organic (total soluble carbohydrates, N - aminossolúveis and free proline) and nutritional state (foliar nutrients of nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, copper, manganese and zinc). The growth and biomass production of the plants are sharply reduced by the conditions of water stress and high soil salinity, apparently being more critical to fluid restriction culture. The degree of water stress can enhance the susceptibility to salinity. The physiological mechanisms are effectively limited when water stress and salinity act separately and / or together. The effects of water stress are more effective in the reduction of physiological parameters, to the detriment soil salinity. The magnitudes of physiological responses of plants to water supply and salinity depend on the intensity of stress. Adaptive physiological responses of plants are related mainly to stomatal regulation. In conditions of drought and soil salinity, the plants have linear reductions in the total levels of chlorophyll. Carotenoid levels respond to the combined effects of water availability and soil salinity and reflect the antagonism between them. The coconut has a number of physiological adjustments mechanisms that give the species a partial tolerance to drought stress and / or saline. Saline ions K+, Na+ and Cl- accumulate significantly in young coconut plants, to the detriment of organic solutes, both in the leaves and in the roots, evidencing an apparent root retention ions. Salinity did not change the concentration of organic solutes, however, show up increments in leaf and root levels of free proline in response to water stress. Water stress and soil salinity interact, affecting the nutritional status of plants, except for the nutrient P. Leaf contents of nutrients N, Ca, S, Fe, Mn and Zn grow positively with the increase of water availability and are reduced substantially with increasing salinity. The interaction of smaller water deficit levels with the highest saline levels maximizes the leaf contents of Mg and Cu and minimizes K. During the establishment of coconut seedlings, the need for macronutrients follows the descending order: N, K Ca, Mg, S and P and micronutrients: Fe, Mn, Zn and Cu. The plant nutrition proved to be adequate, except for the imbalances observed in nutrients K, Mg, S and Mn. The coconut seedlings show full capacity of the establishment in saline soils PIMN, corresponding to the level of electrical conductivity to 6.50 dS m-1, but only when the water supply remains adequate. For the higher salinity levels the plants survive, yet the size of the same is reduced by around 50%, even when fully irrigated. / Neste trabalho foram estudadas repostas morfológicas, fisiológicas, bioquímicas e nutricionais, visando elucidar as possíveis estratégias adaptativas de plantas jovens de coqueiro, cultivar “Anão Verde”, envolvidas com sua tolerância aos efeitos dos estresses isolados e/ou combinados, salinidade do solo e deficiência hídrica. No experimento, conduzido em casa de vegetação, do tipo telado, em Fortaleza, Ceará, avaliaram-se, sob delineamento estatístico de blocos casualizados, no arranjo de parcelas subdivididas, os efeitos de diferentes níveis de deficiência hídrica, mediante a imposição de distintos percentuais de reposições da evapotranspiração potencial da cultura - ETpc (20; 40; 60; 80 e 100%), associados à crescentes níveis de salinidade do solo (1,72; 6,25; 25,80 e 40,70 dS m-1), proporcionados pelos solos oriundos do Perímetro Irrigado Morada Nova - PIMN. Os efeitos dos tratamentos sobre as plantas foram avaliados por meio das variáveis: altura de plantas, número de folhas, diâmetro do caule, área foliar, produção de biomassa (radicular, parte aérea e total), relação biomassa seca raiz parte aérea-1, índices de tolerância à salinidade, trocas gasosas foliares (condutância estomática, transpiração, fotossíntese, eficiência instantânea e intrínseca de uso da água), rendimento quântico da fluorescência da clorofila a (Fv Fm-1), teores relativos de clorofila total (índice Spad), teores totais de clorofilas (a+b) e de carotenóides, potencial hídrico foliar, teores foliares e radiculares dos solutos inorgânicos (íons potássio, sódio e cloreto) e orgânicos (carboidratos solúveis totais, N - aminossolúveis e prolina livre) e estado nutricional (teores foliares dos nutrientes nitrogênio, fósforo, potássio, cálcio, magnésio, enxofre, ferro, cobre, manganês e zinco). O crescimento e a produção de biomassa das plantas são acentuadamente reduzidos pelas condições de restrição hídrica e de elevada salinidade do solo, sendo aparentemente mais crítica à cultura a restrição hídrica. O grau de estresse hídrico é capaz de acentuar a suscetibilidade à salinidade. Os mecanismos fisiológicos são efetivamente limitados quando a deficiência hídrica e a salinidade atuam isoladamente e/ou em conjunto. Os efeitos do estresse hídrico se mostram mais efetivos nas reduções dos parâmetros fisiológicos, em detrimento à salinidade do solo. As magnitudes das respostas fisiológicas das plantas ao suprimento hídrico e à salinidade dependem das intensidades do estresses. As respostas fisiológicas adaptativas das plantas estão relacionadas, principalmente, à regulação estomática. Em condições de déficit hídrico e de salinidade do solo, as plantas apresentam reduções lineares nos teores totais de clorofilas. Os teores de carotenóides respondem aos efeitos combinados da disponibilidade hídrica e da salinidade do solo e refletem o antagonismo entre estes. O coqueiro apresenta uma série de mecanismos de ajustes fisiológicos que conferem à espécie uma parcial tolerância ao estresse hídrico e/ou salino. Os íons salinos K+, Na+ e Cl- acumulam-se significativamente em plantas jovens de coqueiro, em detrimento aos solutos orgânicos, tanto nas folhas quanto nas raízes, sendo evidenciada uma aparente retenção radicular de íons. A salinidade não altera os teores dos solutos orgânicos, todavia, denotam-se incrementos nos teores foliares e radiculares de prolina livre em resposta à deficiência hídrica. A deficiência hídrica e a salinidade do solo interagem, afetando o estado nutricional das plantas, excetuando o nutriente P. Os teores foliares dos nutrientes N, Ca, S, Fe, Mn e Zn crescem positivamente com a ampliação da disponibilidade hídrica e reduzem-se substancialmente com o aumento da salinidade. A interação dos menores níveis de deficiência hídrica com os maiores níveis salinos maximiza os teores foliares de Mg e Cu e minimiza os de K. Durante o estabelecimento das plantas jovens de coqueiro, a necessidade de macronutrientes obedece à ordem decrescente: N, K Ca, Mg, S e P e à de micronutrientes: Fe, Mn, Zn e Cu. A nutrição das plantas mostra-se adequada, excetuando-se, os desequilíbrios observados nos nutrientes K, Mg, S e Mn. As plantas jovens de coqueiro mostram plena capacidade de estabelecimento nos solos salinizados do PIMN, até o nível de condutividade elétrica correspondente a 6,50 dS m-1, porém apenas quando o suprimento hídrico se mantém adequado. Para os níveis de salinidade mais elevados as plantas sobrevivem, contudo o porte das mesmas reduz-se em torno de 50%, mesmo quando plenamente irrigadas.