Growth of lulo (Solanum quitoense Lam.) plants affected by salinity and substrate

The effects of 0, 30 and 60 mM NaCl and substrates (red peat, sand or 3:1:1 [w/w] mixture of peat, sand, or soil) on vegetative growth of lulo, an Andean fruit species, during 12 weeks were studied. The experiment was carried out by using 2000 cm³ of polypropylene plastic pots under greenhouse conditions. Plant height, number of leaves and nodes, leaf area, total plant dry matter (DM), and shoot/root ratio were evaluated. With the increase of salt concentration, the plant height, the number of leaves and nodes, the leaf areas and plant dry mass DM decreased, whereas shoot/root ratio increased. Sand grown lulo plants were most affected by salinity and presented total mortality at 60 mM NaCl. On the other hand, plants held either in peat or in substrate mixture developed larger height, greater leaf and node numbers, higher leaf area and dry matter content. Shoot/root ratio in control (soil) and sand-grown plants (30 mM NaCl) was lower.

Lake-level and salinity reconstruction from diatom analyses in Quillagua Formation (Late Neogene, Central Andean Forearc, Northern Chile)

A sedimentary and micropaleontological study of the Quillagua Formation provides a detailed paleohydrological reconstruction of the lacustrine system which occupied the present-day hyperarid Quillagua-Llamara fore-arc Basin (Northern Chile) from lattermost Miocene to Early Pliocene times.

Fiscal sustainability and fiscal shocks in a dollarized and oil-exporting country: Ecuador

This paper investigates the fiscal sustainability of an emerging, dollarized, oil-exporting country: Ecuador. A cointegrated VAR approach is adopted in testing, first, if the intertemporal budget constraint is satisfied in Ecuador and, second, in identifying the permanent and transitory shocks that affect a fiscal policy characterized by inertia and a heavy dependence on oil revenues. Following confirmation that the debt-GDP ratio does not place the Ecuadorian budget under any pressure, we reformulate the model and identify two forces that push the fiscal system out of equilibrium, namely, economic activity and oil revenues implemented in the government budget. We argue that Ecuador needs to recover control of its monetary policy and to promote the diversification of its economy in order that non-oil tax revenues can replace oil revenues as a pushing force. Finally, we calculate quarterly elasticities of tax revenues with respect to Ecuador’s GDP and that of eight Eurozone countries. We illustrate graphically how the Eurozone countries with low positive or high negative elasticities’ levels suffer debt problems after the crisis. This finding emphasizes the pressing need for Ecuador to strengthen the connection between its tax revenues and output, and also suggests that the convergence of these elasticities in the Eurozone might contribute to the success of an eventually future fiscal union.

A dynamic analysis of asymmetric shocks in EU manufacturing

Available empirical evidence regarding the degree of symmetry between European economies in the context of Monetary Unification is not conclusive. This paper offers new empirical evidence concerning this issue related to the manufacturing sector. Instead of using a static approach as most empirical studies do, we analyse the dynamic evolution of shock symmetry using a state-space model. The results show a clear reduction of asymmetries in terms of demand shocks between 1975 and 1996, with an increase in terms of supply shocks at the end of the period.

Effects of Temperature, Salinity and Fish in Structuring the Macroinvertebrate Community in Shallow Lakes: Implications for Effects of Climate Change

Climate warming may lead to changes in the trophic structure and diversity of shallow lakes as a combined effect of increased temperature and salinity and likely increased strength of trophic interactions. We investigated the potential effects of temperature, salinity and fish on the plant-associated macroinvertebrate community by introducing artificial plants in eight comparable shallow brackish lakes located in two climatic regions of contrasting temperature: cold-temperate and Mediterranean. In both regions, lakes covered a salinity gradient from freshwater to oligohaline waters. We undertook day and night-time sampling of macroinvertebrates associated with the artificial plants and fish and free-swimming macroinvertebrate predators within artificial plants and in pelagic areas. Our results showed marked differences in the trophic structure between cold and warm shallow lakes. Plant-associated macroinvertebrates and free-swimming macroinvertebrate predators were more abundant and the communities richer in species in the cold compared to the warm climate, most probably as a result of differences in fish predation pressure. Submerged plants in warm brackish lakes did not seem to counteract the effect of fish predation on macroinvertebrates to the same extent as in temperate freshwater lakes, since small fish were abundant and tended to aggregate within the macrophytes. The richness and abundance of most plant-associated macroinvertebrate taxa decreased with salinity. Despite the lower densities of plant-associated macroinvertebrates in the Mediterranean lakes, periphyton biomass was lower than in cold temperate systems, a fact that was mainly attributed to grazing and disturbance by fish. Our results suggest that, if the current process of warming entails higher chances of shallow lakes becoming warmer and more saline, climatic change may result in a decrease in macroinvertebrate species richness and abundance in shallow lakes

Labile copper and zinc fractions under different salinity conditions in a shipyard area in the patos lagoon estuary, south of Brazil

Copper and zinc are common elements in paint residues and can be toxic to estuarine organisms. This study aims to determine the labile dissolved and labile particulate fractions (LPFs) of copper and zinc in the estuarine waters of a shipyard in southern Brazil under different salinity levels and in different seasons. The labile dissolved fraction was determined using the diffusive gradient in thin-film (DGT) technique. The variations in DGT-Cu (0.22-1.05 µg L-1), DGT-Zn (0.54-18.39 µg L-1), LPF-Cu (1.22-3.77 µg g-1), and LPF-Zn (4.29-19.12 µg g-1) concentration were related to changes in their physico-chemical parameters and as a result of boat maintenance activities.

Determination of Alkalinity and dissociation constants of high salinity waters: use of F5BC titration function

Measurements of parameters expressed in terms of carbonic species such as Alkalinity and Acidity of saline waters do not analyze the influence of external parameters to the titration such as Total free and associated Carbonic Species Concentration, activity coefficient, ion pairing formation and Residual Liquid Junction Potential in pH measurements. This paper shows the development of F5BC titration function based on the titrations developed by Gran (1952) for the carbonate system of natural waters. For practical use, samples of saline waters from Pocinhos reservoir in Paraiba were submitted to titration and linear regression analysis. Results showed that F5BC involves F1x and F2x Gran functions determination, respectively, for Alkalinity and Acidity calculations without knowing "a priori" the endpoint of the titration. F5BC also allows the determination of the First and Second Apparent Dissociation Constant of the carbonate system of saline and high ionic strength waters.

Germination and early growth of physic nut submitted to levels of salinity

Two experiments were conducted to evaluate the effect of salinity on early physic nut plant development. In the first trial, physic nut seeds were exposed to seven levels of salinity (0, 2, 4, 6, 8, 10 and 12dS m-1) with eight repetitions, using a substrate of paper soaked with solutions of CaCl2 and KCl. The treatments were evaluated based on the initial germination, total percentage of germination, and time necessary to germination of 50% of the seeds. Increased salinity reduced the first germination count and delayed the time to 50% germination. From 10dS m-1, there was a reduction in germination percentage. The second trial evaluated the effect of salinity on the growth of physic nut seeds. This trial, carried out inside a greenhouse, with a completely randomized design, was composed of five salinity treatments (0.02, 2, 4, 6 and 8dS m-1) with 5 replications. It was observed that salinity levels above 2dS m-1 affected plant development. The current study suggests that salinity management is an important factor to be considered to achieve the potential productivity of physic nut.

Acceleration of Solar Energetic Particles in coronal shocks through self-generated turbulence

The acceleration of solar energetic particles (SEPs) by flares and coronal mass ejections (CMEs) has been a major topic of research for the solar-terrestrial physics and geophysics communities for decades. This thesis discusses theories describing first-order Fermi acceleration of SEPs through repeated crossings at a CME-driven shock. We propose that particle trapping occurs through self-generated Alfvén waves, leading to a turbulent trapping region in front of the shock. Decelerating coronal shocks are shown to be capable of efficient SEP acceleration, provided seed particle injection is sufficient. Quasi-parallel shocks are found to inject thermal particles with good efficiency. The roles of minimum injection velocities, cross-field diffusion, downstream scattering efficiency and cross-shock potential are investigated in detail, with downstream isotropisation timescales having a major effect on injection efficiency. Accelerated spectra of heavier elements up to iron are found to exhibit significantly harder spectra than protons. Accelerated spectra cut-off energies are found to scale proportional to (Q/A)^1.5, which is explained through analysis of the spectral shape of amplified Alfvénic turbulence. Acceleration times to different threshold energies are found to be non-linear, indicating that self-consistent time-dependent simulations are required in order to expose the full extent of acceleration dynamics. The well-established quasilinear theory (QLT) of particle scattering is investigated by comparing QLT scattering coefficients with those found via full-orbit simulations. QLT is found to overemphasise resonance conditions. This finding supports the simplifications implemented in the presented coronal shock acceleration (CSA) simulation software. The CSA software package is used to simulate a range of acceleration scenarios. The results are found to be in agreement with well-established particle acceleration theory. At the same time, new spatial and temporal dynamics of particle population trapping and wave evolution are revealed.

Effect of desiccation and salinity stress on seed germination and initial plant growth of Cucumis melo

Smellmelon, an annual invasive weed of soybean production fields in the north of Iran, reproduces and spreads predominately through seed production. This makes seed bank survival and successful germination essential steps in the invasive process. To evaluate the potential of Smellmelon to invade water-stressed environments, laboratory studies were conducted to investigate the effect of desiccation and salinity at different temperatures on seed germination and seedling growth of Cucumis melo. Seeds were incubated at 25, 30, 35 and 40 ºC in the darkness in a solution (0, -0.2, -0.4, -0.6, -0.8, 1 and 1.2 MPa) of a salt (NaCl), and in a solution (0, -2, -4, -6, -8, -10, -12 bar) of PEG-6000 (Polyethylene glycol), in two separate experiments. The results showed that the highest percentage and rate of germination occurred at 35 ºC in salt concentrations of 0, -0.2, -0.4 MPa and PEG concentrations of 0, -2, -4 bar. Increasing the concentration of salt (NaCl) and PEG limited germination, seedling growth and water uptake but increased the sodium content in the seedlings. No significant difference was observed among 0, -0.2 and -0.4 MPa of NaCl and among 0, -2 and -4 bar of PEG concentration at 35 ºC. The negative effects of PEG were more than those of NaCl on germination percentage and germination rate. Increased stress levels lead to reduction of root and shoot length, and SVL of seedlings. Na+ content of seedling decreased with limited seedling growth of C. melo.

Acute and chronic effects of cadmium on blood homeostasis of an estuarine crab, Chasmagnathus granulata, and the modifying effect of salinity

Whole body oxygen consumption and some hemolymph parameters such as pH, partial pressure of gases, level of ions and lactate were measured in the estuarine crab Chasmagnathus granulata after both acute (96 h) and chronic (2 weeks) exposure to cadmium at concentrations ranging from 0.4 to 6.3 mg/l. In all instances, the crabs developed hemolymph acidosis, but no respiratory (increased PCO2) or lactate increases were evident. Hemolymph levels of sodium and calcium were always increased by cadmium exposure. The chronic toxicity of cadmium was enhanced at 12‰ salinity, even causing a significantly higher mortality in comparison with the higher salinity (30‰) used. A general metabolic arrest took place at 12‰ salinity in the crabs chronically exposed to cadmium, as indicated by decreases of oxygen consumption and PCO2, an increase of PO2, along with no changes in lactate levels. These imbalances were associated with severe necrosis and telangiectasia in the respiratory gills, probably leading to respiratory impairment and finally histotoxic hypoxia and death of the animals.

Regime-Switching in the Impact of Oil Price Shocks on Stock Market Volatility: Evidence from Oil-Importing and Oil-Exporting Countries

Research has highlighted the adequacy of Markov regime-switching model to address dynamic behavior in long term stock market movements. Employing a purposed Extended regime-switching GARCH(1,1) model, this thesis further investigates the regime dependent nonlinear relationship between changes in oil price and stock market volatility in Saudi Arabia, Norway and Singapore for the period of 2001-2014. Market selection is prioritized to national dependency on oil export or import, which also rationalizes the fitness of implied bivariate volatility model. Among two regimes identified by the mean model, high stock market return-low volatility regime reflects the stable economic growth periods. The other regime characterized by low stock market return-high volatility coincides with episodes of recession and downturn. Moreover, results of volatility model provide the evidence that shocks in stock markets are less persistent during the high volatility regime. While accelerated oil price rises the stock market volatility during recessions, it reduces the stock market risk during normal growth periods in Singapore. In contrast, oil price showed no significant notable impact on stock market volatility of target oil-exporting countries in either of the volatility regime. In light to these results, international investors and policy makers could benefit the risk management in relation to oil price fluctuation.

Physiological response of cowpea seeds to salinity stress

This work aimed to evoluate physiological response of cowpea (Vigna unguiculata L. Walp) seeds submitted to salt stress. Seeds of cultivars 'Epace-10'; 'Canapu' and 'Pitiúba' of cowpea, were submitted to germination test in germinator at 25(0)C, in "germitest" papers imbibed in distilled water or in 0, 10, 50, 100 and 200mol m-3 NaCl solutions. At the first and second counting of the germination test, normal seedlings were accounted, weighted and dried, obtaining data for vigor, total germination, fresh matter weight and dry matter weight. The seedlings hypocotyls, root and total length were measured total proteins content in cotyledons were obtained from germinating seeds. The presence of salt at concentrations higher than 50mol m-3 NaCl affect the germination, seedlings growth and cotyledons total protein synthesis of all cowpea cultivars. The seeds of cultivar pitiúba were is more tolerant to salinity, than the cultivars Canapu and Epace-10.