Peatlands are areas with an accumulated layer of peat soil that are considered global stores of carbon, acting as a net sink of carbon dioxide and a net source of methane. Recent studies in coastal peatlands have shown how that a rise in sea level may contribute to the degradation of peat soils due to the inland progression of the saltwater interface, which may result in physical changes within the peat matrix that may eventually result in peat collapse. For example, earlier studies in boreal peat soils described the effect of pore dilation as a result of increased salinity in peat soils, while recent studies in Everglades peat soils showed specific salinity thresholds that may represent a permanent loss of the structural integrity of the peat matrix that may represent early stages of peat collapse. While most of these previous efforts have focused on drivers, recent work has also explored conceptual models to better understand the mechanisms inducing peat collapse. However, few datasets exists that consistently compare differences in physical properties under different in‐situ salinity conditions. In this study differences in the physical properties of peat soils across a salinity gradient along the western edge of Big Cypress National Preserve are investigated to test how differences in salinity may induce physical changes in the soil matrix. The physical properties targeted for this study include porosity, hydraulic conductivity, and carbon content. Measurements are conducted at the laboratory scale using peat cores and monoliths collected at selected locations to investigate: 1) how overall soil physical properties change spatially over a salinity gradient at the km scale moving from permanently saline to freshwater conditions; and 2) how physical properties change spatially at specific sites as dependant on vegetation boundaries and proximity to collapsed soils. This study has implications for better understanding the potential relation between physical changes of the soil matrix and the phenomena of peat collapse in the Everglades as saltwater intrusion progresses inward and alters freshwater ecosystems. Furthermore, a better mechanistic understanding of the peat collapse phenomenon can potentially help mitigate its occurrence. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

Dans leur environnement naturel, les plantes doivent continuellement s’adapter pour survivre aux diverses stimuli auxquels elles sont confrontées. La salinité est responsable de fortes pertes de rendements et une meilleure compréhension des mécanismes capables d’induire la tolérance de la plante est nécessaire. Au niveau cellulaire, les stress biotique et abiotique perçus induisent la production de messagers secondaires ce qui active des voies de signalisation faisant intervenir différentes familles de protéines kinases dont les protéines kinases dépendantes du calcium, les CDPKs. Lorsqu’elles sont activées, elles vont phosphoryler des substrats permettant la mise en place des réponses spécifiques au stress perçu.CPK5 et CPK6 sont des régulateurs positifs de la tolérance au stress salin et également de la résistance aux bactéries, notamment par l’induction de gènes de réponses. L’identification de 25 nouveaux substrats putatifs par une approche phosphoprotéomique pourraient permettre une meilleure compréhension du rôle de CPK5 et CPK6 dans la réponse aux stress. Parmi les candidats étudiés dans ce manuscrit, six ont été validées in vitro, notamment deux ubiquitine ligases E3 dont la mutation d’un site conservé inhibe la phosphorylation par CPK5 et CPK6. Bien que l’étude des mutants knock-out n’ait pas permis de leur attribuer un rôle dans la tolérance à la salinité, certains pourraient agir en aval de CPK5/6 dans la réponse aux pathogènes. / Plants are subjected to several environmental stimuli and must adapt to survive. A better understanding of the mechanisms involved in plant tolerance is necessary to find solution to the salt stress that is responsible for important yield loss. At the cellular level, the perception of biotic and abiotic stress leads to the accumulation of secondary messengers that activate protein kinases involved in different signaling pathways as calcium-dependent protein kinases (CDPKs). Once they are activated, CDPKs can phosphorylate substrates which are able to induce appropriate responses to the stimuli.CPK5 and CPK6 are positive regulators of salt stress and biotic stress, notably through the induction of response genes. To better understand their roles in plant stress response, a phosphoproteomic approach was conducted and could identify 25 new putative substrates for CPK5. Six of the studied candidates were validated in vitro for phosphorylation by CPK5 and CPK6. Among them, two ubiquitin E3 ligases are not phosphorylated anymore by CPK5 and CPK6 when mutated on a conserved phosphosite. Unfortunately, the knock-out mutants of the substrates in salt condition did not show any phenotype. However some of them are known to play a role in response to pathogen and could act downstream of CPK5 and CPK6.

>Magister Scientiae - MSc / As the global human population grows, so does the demand for faster food production rates. Owing to this, agricultural practices have had to expand and move into semi-arid and arid regions, too, where frequent irrigation is essential. However, irrigated ground water contains many salt ions (mainly Na+ and Cl-) which contribute to soil salinization on croplands. Soil salinity negatively impacts crop growth and yield and thus, strategies for the alleviation of salt stress on crop plants have had to be developed. This study assessed the use of plant growth promoting bacteria (PGPB). The aim of this study was to isolate, identify and characterize bacterial endophytes isolated from the halophyte, Arctotheca calendula. Endophytes were identified using 16S rDNA and were screened for plant growth promoting properties including nitrogen fixation, phosphate and zinc solubilization, siderophore, ammonia and indole-3-acetic acid (IAA) when exposed to 0 mM, 300 mM and 600 mM NaCl. The endophytes had been identified as Erwinia persicina NBRC 102418T, Bacillus marisflavi JCM 11544T, Ochrobactrum rhizosphaerae PR17T, Microbacterium gubbeenense DSM 15944T and Bacillus zhangzhouensis DW5-4T and all of which had demonstrated some plant growth promoting characteristics. Thereafter, we aimed to demonstrate plant growth promotion of P. vulgaris cv. Star 2000 inoculated with PGPB under salinity stress. P. vulgaris cv. Star 2000 seeds were inoculated with the PGPB and exposed to 0 mM and 100 mM NaCl. Post-harvest, plants were assessed for their dry mass, cell death, superoxide concentration and nutrient content. It was discovered that salinity negatively impacted P. vulgaris cv. Star 2000’s dry mass, NaCl-induced cell death, and differentially influenced superoxide concentration, nutrient uptake and content of the leaf and root material in the inoculated and control treatments. However, the isolated PGPB had been able to mitigate the negative effects of soil salinity on P. vulgaris cv. Star 2000.

Drought has an increasing importance in the Czech republic. It is necessary to look for potential irrigation water sources, which are important for agriculture. Treated wastewater can be one of them. It has potentially negative impact on soil physico-chemical properties, which is well-known from many researches in arid regions. The aim of this diploma thesis was to investigate, if the drip irrigation with treated wastewater (from constructed wetland) also has a potentially negative impact on two soils in the Czech republic. In one year experiment drip irrigation with treated wastewater was carried out in the greenhouse. Four treatments of irrigation was used for both soils - irrigation with treated wastewater, irrigation with groundwater, irrigation with treated wastewater + rainwater, irrigation with groundwater + rainwater. An amount of rainwater correspond with total precipitation of two locations, where the soils were brought from (Kostelec nad Ohří - Ústí nad Labem region and Hostětín - Zlín region). pH and electrical conductivity of soil leachate, total concentration of Na, K, Ca, Mg a P, bulk density, particle density and porosity was measured in both soils in 5 and 10 centimeters from source of irrigation. Values of pH of soil leachate fluctuated in every treatment in both soils during the...

Stockholm archipelago is a combination of coastal and young glaciated conditions on hard rock geology with almost no primary porosity and very limited secondary porosity. Therefore the aquifer is both of limited capacity and exposed to salinity problem. In this context importance of fractures and soil cover is magnified. Lineaments are representatives of fractures in remote sensing. Fracture mapping in study area proves close correspondence between orientation of fractures and nearly located lineaments. Especially in this type of terrain, lineaments normally occur together with many other interesting hydrogeological features such as topographic attributes, soil, and vegetation; however, still each of these factors has its own effect on the groundwater situation. Through employment of geostatistical analysis and a modified variant of the RV (Risk Variable) method, called the PV (Probability Value) method, different attributes are rated by importance. The results show, soil cover is the most influencing factor then rock type and distance from lineaments; other factors are classified after them. It is discovered that the center of lineaments may not be the most suitable site to extract water because of being clogged by fills. This is particularly the case for shear fractures in which clay can be internally formed due to friction. Based on the statistical results a model is made in GIS environment in order to create hydrogeological maps. Such maps, after validation, can be used for any other area with similar properties even with missing or very limited data from boreholes. These maps definitively are only probability maps projecting areas with higher and lower prospect of aquifer potential and cannot guarantee high capacity in every borehole drilled in designated areas due to high heterogeneity of fractured rock system. Analysis of chemical data from wells proves a correlation between fracture orientations and topography with salinization and groundwater flow. Groundwater flow in the surroundings seems to be essential for feeding the aquifer as most of the wells with increased salt content have also low capacities.

Almost 50 % of drinking water in Sweden comes from aquifers. The sustainability of groundwater resources in Stockholm County is threatened by increased salinity although most of the drinking water comes from Lake Mälaren. For a region known to be located within the areas covered by seawater after the last glaciation, the health and socio-economic development of the county is in a balance as development plans are challenged by high risk of salt groundwater. It is therefore important to know the extent and spread of salinity within the areas and the factors that correlate well with the salinity in the first attempt to study the risk of the areas to high salt content of groundwater. This paper looks at the distribution of salinity within the county and analyses the correlation between salinity and several natural factors. Using well co-ordinates and chemical data (compiled by Stockholm County Administration), and digital topographical, geological and land use data (from SGU and Swedish Land Survey), it is possible to project and visualize wells and salinity over the area, spatially develop and extract natural factor values to respective wells based on their co-ordinates, and finally perform statistical analyses on a resultant well attributes table, with the aid of Surfer, ArcGIS and Statistica Software. Results showing the spatial distribution of wells’ salinity and graphs of variance between the salinity of wells and respective natural factors of topography, depth, predominant soil cover, land use and distance from the sea, are further discussed.

Salinity is a major concern in agriculture since it adversely affects plant growth, development, and yield. Domestication of crops exerted strong selective pressure and reduced their genetic diversity. Meanwhile, wild species continued to adapt to their environment becoming valuable sources of genetic variation, with the potential for enhancing modern crops performance in today’s changing climate. Some wild species are found in highly saline environments; remarkable examples are the endemic wild tomatoes from the Galapagos Islands, forming the Solanum cheesmaniae and Solanum galapagense species (hereafter termed Galapagos tomatoes). These wild tomatoes adapted to thrive in the coastal regions of the Galapagos Islands. The present work includes a thorough characterization of a collection of 67 accessions of Galapagos tomatoes obtained from the Tomato Genetics Resource Center (TGRC). Genotyping-by-sequencing (GBS) was performed to establish the population structure and genetic distance within the germplasm collection. Both species were genetically differentiated, and a substructure was found in S. cheesmaniae dividing the accessions in two groups based on their origin: eastern and western islands. Phenotypic studies were performed at the seedling stage, subjecting seedlings to 200 mM NaCl for 10 days. Various traits were recorded and analysed for their contribution to salinity tolerance, compared to control conditions. Large natural variation was found across the collection in terms of salt stress responses and different possible salt tolerant mechanisms were identified. Six accessions were selected for further work, based on their good performance under salinity. This experiment included scoring several plant growth and yield-related traits, as well as RNA sequencing (RNAseq) at the fruit-ripening stage, under three different NaCl concentrations. Accession LA0421 showed an increased yield of almost 50% in mild salinity (150 mM NaCl) compared to control conditions. The transcriptome data obtained could reveal the genes involved in the salt stress-related yield increase. The knowledge obtained so far will be useful for scientists and breeders to select accessions of interest based on recorded traits. It will allow the use of Galapagos tomatoes as genetic sources for salinity tolerance traits in commercial tomatoes, thereby contributing to feed and nourish the growing human population in the years to come.

Crude oil recovery is related to surface wettability, which is controlled by crude interactions with rock surfaces. Understanding these interactions is associated with studying the complex asphaltenes that (1) are irreversibly deposited from oil-brine interfaces onto reservoir mineral surfaces, (2) are bulky super-molecules and (3) incorporate several chemical groups by stacking aromatic rings together. This is a difficult task because of varying crude oil composition, asphaltene interfacial and chemical activity, and the potential of irreversibly contaminating analytical equipment by such substances. To overcome these challenges, we split the problem into parts by studying how different mono- and poly-functional groups mimic asphaltene interaction with mineral surfaces, such as silica and calcium carbonate. The amine, carboxylate, and sulfate groups were identified as the highest potential functional groups responsible for asphaltene adsorption. Experiments included quartz crystal micro-balance with dissipation, bulk adsorption, and core samples. Adsorption tests for the mono-functional surfactants studied were fully reversible and, therefore, not representative of asphaltenes. Poly-functional compounds demonstrated irreversible adsorption, mimicking asphaltenes, through ion exchange and ion-bridging, depending on the type of functional group, chain length, mineral surface, and brine ionic composition. Poly-amines adsorb irreversibly onto silica and calcium carbonate surfaces regardless of the brine ionic composition or surface charge. However, irreversible adsorption of poly-sulfates and poly-carboxylates onto surfaces requires (1) sufficiently long chains and (2) an abundant presence of calcium ions in solution to allow ion-bringing mechanism. These findings suggest that crudes containing amine groups and long chains of carboxylates or sulfates have a higher tendency to be adsorbed onto surfaces and change wettability. This is important for designing an efficient detachment of asphaltenic oil from rock surfaces, where no complete desorption or drastic wettability change is required. The weakening of asphaltene interactions may be sufficient to induce spontaneous imbibition and consequently increase the efficiency of two-phase displacement. This work emphasizes the importance of understating crude-brine-rock interactions for the purpose of oil recovery. In summary, evaluating potential candidates for deploying enhanced oil recovery, such as low salinity waterflooding, should consider rock and crude types, as successful implementation requires “specific” properties collaborating together to enable incremental oil production

Both salinity and drought stresses induce osmotic stress. Thus, cross-tolerance responses and mechanisms may occur in plants. The overall objectives of this study were to determine morphological and physiological responses and mechanisms of turfgrasses and woody species under salinity and drought stress conditions, and determine the relationship between drought and salinity tolerance ability in those species. Five turfgrass entries, ‘Gazelle’ and ‘Matador’ tall fescue (TF), ‘Midnight’ Kentucky bluegrass (KBG), PI368233 (Tolerant KBG), and PI372742 (Susceptible KBG), and three woody species, bigtooth maple (xeric-non saline), bigleaf maple (mesicnon saline) and Eucalyptus (mesic-saline) were compared. For the drought study, water was withheld in Chapter 2 while the dry down treatment was based on daily evapotranspiration (ET) in Chapters 5 and 6. For the salinity study, NaCl and CaCl2 in turfgrasses at electrical conductivity (EC) of 1, 6, 12, 18, and 30 dS m-1 (Chapter 3) and woody species at EC of 1, 3, 6, 9, and 12 dS m-1 (Chapter 4). Susceptible KBG was sensitive to s

The potential of basin wildrye (Elymus cinereus Scribn. & Merr. 'Magnar') and tall wheatgrass [Agropyron elongatum (Host) Beav. 'Jose '] to establish on saline, arid rangelands in the Great Basin in relation to soil water and salinity was compared in field and laboratory experiments. Tall wheatgrass had higher emergence and establishment on a nonsaline and a saline soil (electrical conductivity of the saturation extract of 7 dS·m-1) over a range of spring precipitation as simulated by sprinkler irrigation. Basin wildrye will require supplemental irrigation to establish on soils of similar salinity. In the absence of precipitation, soil salinity increases and matric and osmotic potentials rapidly decrease as the surface soil dries in late spring. Germination and growth responses in relation to salinity and drought in laboratory experiments were consistent with emergence and establishment results in the field experiments. Tall wheatgrass had higher total germination, rate of germination and radicle growth under decreasing osmotic potentials and higher emergence under decreasing matric potentials than basin wildrye. Tall wheatgrass had greater root and shoot yield than basin wildrye when osmotic potentials in sand cultures were decreased by solutions of NaCl, Na2SO4 and CaCl2.Tall wheatgrass is more tolerant of salt and boron than basin wildrye, but basin wildrye is highly salt tolerant compared to most forage species. Tall wheatgrass had more rapid root elongation and more extensive root growth than basin wildrye seedlings grown in 60-cm soil columns filled with nonsaline and saline soil. Germination and growth of both species was reduced by ions in addition to the effects of water stress due to low osmotic potentials. Rate of germination and radicle growth of both species was less in salts than in isosmotic polyethylene glycol solutions. Seedlings exhibited less growth in saline than nonsaline soil even when plant water stress was minimal or when leaf water potentials were low but turgor was maintained by osmotic adjustment. Germination at low osmotic and matric potentials and root elongation in relation to salinity may be important plant responses to use in evaluating the potential for establishment of new plant materials on saline, arid rangelands.