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Salinity Levels (salinity + level)

Distribution by Scientific Domains

Earth and Environmental Science	51%
Life Sciences	39%
2 Other Domains	10%

Selected Abstracts

Effects of salt stress on purslane (Portulaca oleracea) nutrition

ANNALS OF APPLIED BIOLOGY, Issue 1 2009
M. Teixeira
Abstract The objective of this study was to determine the influence of saline stress on the chemical composition of purslane (Portulaca oleracea), in particular the mineral composition. Four salinity levels were investigated using irrigation solutions with electrical conductivity values of 0.8, 6.8, 12.8 and 24.2 dS m,1 and two planting dates (May and July) were tested. Samples of full-grown leaf and stems of purslane were harvested after 7 and 15 days of the saline treatment exposure. Chemical analysis (dry matter basis) of leaves showed significant differences among the different saline treatments for all the characteristics measured. Salinity levels, planting date and harvest time significantly influenced (P < 0.05) the levels of crude protein, total lipids, ash and carbohydrate content. Salinity treatments did not significantly (P > 0.05) affect the water content of purslane leaves. The crude protein content of purslane leaves decreased with increasing salinity levels and time of exposure to treatment. However, carbohydrates and mineral residue content increased. An unusual phenomenon was noted for intermediate salinity levels, whereby an increase in total lipid content was measured in leaves of plants exposed to salinity treatments of 6.8 and 12.8 dS m,1. The highest mineral residue content was seen in leaves of purslane exposed to the highest salinity treatment. The mineral composition was also affected by salinity levels, Na and Cl uptake, and accumulation increased with increasing salinity in irrigation solution; Mg concentration was not significantly (P > 0.05) affected by salinity levels, although a slight increase was seen, and Ca, K and Zn levels significantly (P < 0.05) decreased. Ca and Zn preferentially accumulated in the leaves, while K and Na values were higher in the stems. A significant increase (P < 0.05) in relative ratio of Na/K, Mg/K, Na/Ca and Mg/Ca was observed with increasing salinity levels. A decrease in the yield of purslane was only observed for the most severe saline treatment, where the highest ratio of Mg/Ca was seen. This study reveals that purslane is relatively tolerant to conditions of moderate salinity, thus improving its potential to become a key vegetable crop for animal and human consumption. [source]

Protein requirements of Nile tilapia (Oreochromis niloticus) fry cultured at different salinities

AQUACULTURE RESEARCH, Issue 8 2010
Edvino Larumbe-Morán
Abstract Effect of isolipidic (62.7 ± 5.0 g kg,1) diets with protein levels of 204.6 (T20), 302.3 (T30), 424.6 (T40) or 511.0 g kg,1 (T50) on growth and survival in Nile tilapia (Oreochromis niloticus Linnaeus 1758) fry cultured for 70 days at one of four salinities (0, 15, 20 and 25 g L,1) was evaluated. A bifactorial (4 × 4) design was used with 16 treatments run in triplicate and 20 fry (0.25 ± 0.04 g) per replicate under semi-controlled conditions. Four independent, recirculating systems (one per salinity level) were used, each one with 12 circular tanks (70 L capacity), filters and constant aeration. The different salinities had no significant effect on growth. Weight gain improved significantly as dietary protein content increased, although organisms fed the T50 diet had a lower growth rate. Survival was highest (98.33%) in the T50/15 (protein/salinity levels) treatment and lowest (71.0%) in the T20/20 treatment, with no pattern caused by the variables. The T40/25, T40/20 and T50/0 treatments produced the most efficient growth and feed utilization values while the T20 treatments at all the salinities resulted with the lowest performance. With the exception of the T50 treatments, a non-significant tendency to increased weight gain was observed as water salinity increased, suggesting that the salinity of the culture environment does not influence dietary protein requirements in Nile tilapia O. niloticus fry. [source]

CYST,THECA RELATIONSHIP, LIFE CYCLE, AND EFFECTS OF TEMPERATURE AND SALINITY ON THE CYST MORPHOLOGY OF GONYAULAX BALTICA SP.

JOURNAL OF PHYCOLOGY, Issue 4 2002
NOV. (DINOPHYCEAE) FROM THE BALTIC SEA AREA
A new species of Gonyaulax, here named Gonyaulax baltica sp. nov., has been isolated from sediment samples from the southeastern Baltic. Culture strains were established from individually isolated cysts, and cyst formation was induced in a nitrogen-depleted medium. Although G. baltica cysts are similar to some forms attributed to Spiniferites bulloideus and the motile stage of G. baltica has affinities with G. spinifera, the combination of features of cyst and motile stage of G. baltica is unique. The culture strains were able to grow at salinity levels from 5 to 55 psu and formed cysts from 10 to 50 psu. Cultures at each salinity level were grown at 12, 16, and 20° C. Temperature- and salinity-controlled morphological variability was found in the resting cysts. Central body size varied with temperature and salinity, and process length varied with salinity. Cysts that formed at extreme salinity levels displayed lower average process length than cysts formed at intermediate salinity levels, and central body length and width were lowest at higher temperature and lower salinity. Models for the relationship between central body size and temperature/salinity and process length and salinity have been developed and may be used to determine relative paleosalinity and paleotemperature levels. Our results on salinity-dependent process length confirm earlier reports on short-spined cysts of this species found in low salinity environments, and the model makes it possible to attempt to quantify past salinity levels. [source]

The Effects of Temperature and Salinity on Early Life Stages of Black Sea Bass Centropristis striata

JOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 3 2004
David L. Berlinsky
Along the Atlantic coast black sea bass occur from the Gulf of Maine to Florida and support important commercial and recreational fisheries. Interest in commercial production of black sea bass has increased in recent years due to high demand and limited seasonable availability. Efforts towards large-scale production have been hampered by a high incidence of early larval mortality. Two of the most important environmental variables affecting hatchery production of marine finfish larvae are temperature and salinity. In the wild, larval black sea bass are found in waters with temperatures of 12,24 C and salinity levels of 30,35 ppt. Studies were conducted to define the temperature and salinity ranges that support growth and development of black sea bass during early life stages. Three developmental phases were investigated: 1) fertilization to hatch: 2) hatch through yolk sac absorption: and 3) during the initial exogenous feeding stage (5,14 days post hatch: DPH). Fertilized eggs were obtained by manual spawning of fish following administration of LHRHa. Fertilized eggs were transferred to 300-mL glass Petri dishes or 500-mL beakers to assess the effects of salinity and temperature through hatch and yolk sac absorption, respectively. To determine environmental effects on growth and survival during initial exogenous feeding 400 actively feeding larvae were cultured in green water and fed enriched rotifers for a 9-d period. For investigation of the effect of salinity, sea water (35 ppt) was diluted gradually to 15, 20, 25, and 30 ppt and maintained at 21 C. For examination of the effect of temperature, seawater was adjusted from 21 C to 12, 15, 21, 27, or 30 C at a rate of 3 C/h. No eggs hatched at 12 C or when salinity was maintained at 0 or 5 ppt. Hatching was uniformly high (, 85%) at temperatures between 15 and 27 C and at salinities , 15 ppt. Survival through yolk sac absorption was greatest at temperatures between 18 and 27 C and at salinities , 20 ppt. Survival through first feeding stage was highest at temperatures , 18 C and 30 ppt salinity. Larval growth through first feeding was not significantly affected by salinity level but did increase with rearing temperature. The results indicate that survival and development of black sea bass during early life stages are most favorable at temperatures >18 C with salinity levels approaching full strength seawater. [source]

Reducing salinity and organic contaminants in the Pearl Harbor dredged material using soil amendments and plants

REMEDIATION, Issue 4 2002
N. V. Hue
Phytoremediation is an emerging technique that can be used to economically remediate sites contaminated with trace elements and/or man-made organic contaminants. This technique was used on Pearl Harbor (Oahu, Hawaii) dredged material (PHDM) containing polycyclic aromatic hydrocarbons (PAHs) and some heavy metals. The dredged material was first amended with a high-calcium soil (Waialua Mollisol) and a biosolids-based compost at different proportions to yield varying salinity levels. A mixture that yielded an electrical conductivity (EC, a measure of salinity) of the saturated paste extract of 15 to 20 dS/m was identified and used to evaluate the salt tolerance of five plant species. Relative germination and one-month-old biomass indicated that common bermuda grass (Cynodon dactylon), seashore paspalum (Paspalum vaginatum), beach pea (Vigna marina), and cow pea (Vigna unguiculata) can produce at least 40 percent of biomass of the control at an EC of approximately 18 dS/m, suggesting the four plants are relatively salt tolerant. In contrast, Desmodium intortum either did not germinate or died within two weeks after germination at the same salinity level. A subsequent greenhouse experiment, using mixtures of the PHDM (0 or 25 percent dry weight), organic amendments (10 percent leucaena green manure or biosolids-based compost), and a Mollisol (65 or 90 percent dry weight) in 6-liter pots containing 4 kilograms of material yielded the following results: (1) A combination of transplanted seashore paspalum, seeded bermuda grass, and seeded beach pea was effective in taking up sodium (Na), thereby reducing salinity and making the medium more amenable to diversified microbes and plants, which may be effective PAH degraders; (2) total PAH concentration was reduced by about 30 percent after three months of active plant growth, but degradation of individual PAH members varied significantly, however; (3) leguminous green manure, as a soil amendment, was more effective than compost for use in bio- and/or phytoremediations; and (4) soil amendments, when applicable, could supplement living plants in reducing organic contaminants, such as PAHs. © 200 Wiley Periodicals, Inc. [source]

Protein requirements of Nile tilapia (Oreochromis niloticus) fry cultured at different salinities

Effect of salinity on carrying capacity of adult Nile tilapia Oreochromis niloticus L. in recirculating systems

AQUACULTURE RESEARCH, Issue 16 2006
M A Kabir Chowdhury
Abstract Effect of salinity on carrying capacity of a recirculation system for Nile tilapia, Oreochromis niloticus L.; production was assessed. Survival, growth and feed conversion ratio of adult Nile tilapia fed 30% crude protein diet for 88 days were measured at three different salinity levels (8, 15 and 25 g L,1) and two stocking densities (20 and 40 m,3) in three independent recirculating systems. Highest survival (98%) and a linear growth in net biomass (P<0.01) was observed in both densities at 8 g L,1 and in 20 m,3 treatment at 15 g L,1. Highest net biomass growth was observed in the 40 m,3 stocking density treatment at 8 g L,1 salinity level (P<0.05). Overall biomass growth was significantly affected by salinity indicating a decrease in Nile tilapia carrying capacity with increased salinity. About 11 000 kg ha,1 crop,1 of Nile tilapia can be obtained in recirculating systems at 8 g L,1 salinity, significantly higher than the net production at 15 g L,1 (5200 kg ha,1 crop,1) and 22 g L,1 (4425 kg ha,1 crop,1). [source]

Salinity as a structuring factor for the composition and performance of bacterioplankton degrading riverine DOC

FEMS MICROBIOLOGY ECOLOGY, Issue 2 2003
Silke Langenheder
Abstract The impact of salinity on the composition and functional performance (biomass production, growth efficiency and growth rates) of bacterial communities was investigated using batch cultures growing on dissolved organic carbon from a river draining into the Northern Baltic Sea. The cultures were adjusted to riverine or estuarine salinity levels and inoculated with bacteria from these two environments. Bacterial growth efficiencies differed in response to salinity and the origin of the inoculum. When salinity was adjusted to correspond to the salinity at the site where the inoculum was retrieved, growth efficiency was relatively high (11.5±2.6%). However, when bacteria were confronted with a shift in salinity, growth efficiency was lower (7.5±2.0%) and more of the utilized carbon was respired. In contrast, growth rates were higher when bacteria were exposed to a change in salinity. The composition of the bacterial communities developing in the batch cultures differed, as shown by 16S rDNA DGGE, depending on the origin of the inoculum and salinity. Reverse and direct DNA,DNA hybridization revealed salinity optima in the growth of specific bacterial strains as well as broader phylogenetic groups. Strains belonging to the ,- and ,- Proteobacteria, Actinobacteria and ,- Proteobacteria other than the genus Pseudomonas showed higher relative abundance under freshwater conditions, whereas strains of the genus Pseudomonas and the Cytophaga,Flavobacterium,Bacteroides group were favored by estuarine conditions. Generally, our results demonstrate functional changes associated with changes in community composition. We suggest that even moderate changes in salinity affect bacterial community composition, which subsequently leads to altered growth characteristics. [source]

The impact of salinity pulses on the emergence of plant and zooplankton from wetland seed and egg banks

FRESHWATER BIOLOGY, Issue 5 2007
DARYL L. NIELSEN
Summary 1. In this study we compared the emergence of aquatic biota from sediments under 14-day pulses of high (5000 mg L,1) and low (1000 mg L,1) salinity with emergence under freshwater and equivalent constant salinity levels. We tested the hypothesis that pulses of high salinity and short duration have no impact on the emergence of aquatic plants and zooplankton from wetland sediment. 2. The way salt is moved through the landscape may alter the response of biota to increases in salinity. Under natural hydrological regimes in rivers and floodplains salinity pulses occur often at concentrations that exceed predicted tolerance levels for aquatic biota. The impacts of natural pulses of high salinity followed by rapid return to fresh conditions may be used to inform management guidelines for the potential release of non-natural saline water into river systems with minimal impact. 3. For both aquatic plants and zooplankton the abundance and richness of the emerging taxa decreased at higher salinities kept at constant levels. In contrast, pulses of salinity followed by return to freshwater conditions did not have a negative impact on the emergence of aquatic plants or zooplankton. For many taxa of zooplankton a positive impact was demonstrated with higher emergence following the salinity pulse. 4. The responses of aquatic plant and zooplankton taxa are grouped into five response types. Type 1: negatively impacted by all salt regimes. Type 2: preference for constant salinities. Type 3: no difference between fresh and either pulse regime. Type 4: preference for high concentration pulses. Type 5: emergence higher under a low concentration pulse. 5. Although previous studies indicate that constant high-level salinity in rivers and wetlands can decrease the species richness of aquatic communities, this current study shows pulses may not have the same impact. Our results support the hypothesis that pulses of high salinity and short duration do not impact on the emergence of aquatic plants and zooplankton from wetland sediments. For zooplankton, pulses of salt may trigger emergence. 6. These trends may be used to explore the potential to use managed water releases to move salt through the landscape with minimal impact of salinity on aquatic biota. However, before such preliminary results are applied in management of saline water releases we need to determine the implications for interacting processes in natural ecosystems. [source]

Late prehistoric soil fertility, irrigation management, and agricultural production in northwest coastal Peru

GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 1 2004
Lee Nordt
The Pampa de Chaparrí (Pampa) in hyperarid northwest coastal Peru is an ideal area to study late prehispanic agricultural technology and production because irrigation canals and furrowed fields have been preserved since abandonment approximately 500 years ago. We collected 55 samples for soil characterization, fertility, and micromorphic analyses and compared these results to a noncultivated control soil previously sampled in an adjacent valley. Natural soil fertility levels for maize, cotton, and bean production were generally high during late prehispanic cultivation in the Pampa. Maintaining adequate nitrogren levels for production, however, would have required external inputs from livestock manure, guano, or leguminous plants. The management of low soil salinity levels was possible because of rapidly permeable soils and irrigation waters low in salt. Based on available water capacity and climate conditions, the Blaney-Criddle Equation yields evapotranspiration rates indicating that irrigation frequency was necessary in a range of every 10,16 days during the growing season. © 2004 Wiley Periodicals, Inc. [source]

Brackish water subirrigation for vegetables,

IRRIGATION AND DRAINAGE, Issue 2 2003
R. M. Patel
eaux saumâtres; irrigation souterraine; poivron vert; pommes de terre Abstract As freshwater resources for irrigation are being depleted rapidly, recent emphasis has been on the development of nonconventional water sources: reuse of agricultural drainage water, use of industrial or municipal wastewater, and use of brackish water for irrigation. Experiments conducted in field lysimeters over three seasons sought to investigate the feasibility of using brackish water for growing moderately sensitive crops. Brackish waters, with salinity levels of 1, 5 and 9 dS m,1, were used. In 1993 the effects of a factorial combination of three subirrigation water salinity levels, two water table depths and four NPK fertilizer combinations on salt buildup in an initially nonsaline soil and on green pepper (Capsicum annuum L.) performance were assessed. A gradual increase in soil solution salinity (ECsw) from the water table to the soil surface was evident; however, throughout the growing season, the ECsw did not reach a level that could seriously damage the crop. There was no significant difference in pepper yields due to either salinity of subirrigation water or water table depth. In 1994, two potato (Solanum tuberosum L.) cultivars were grown in the soil, which was salinized with 3.5 dS m,1 water before planting tubers. The salt buildup pattern was similar to that observed in 1993; however, the ECsw levels were higher in 1994 due to the higher initial soil salinity. Moreover, a decrease in ECsw was observed near the water table in lysimeters subirrigated with 1 dS m,1 water. For both cultivars, no significant difference in tuber yield was observed due to either water table depth or subirrigation water salinity. In 1995, three potato cultivars were grown in a nonsaline soil as well as a soil presalinized with 2 dS m,1 water. In the topsoil layer, higher rate of increase in ECsw was observed in the saline soil compared to the nonsaline soil. No significant difference in total tuber yield was observed due to either the initial soil salinity levels or subirrigation water salinity levels. Brackish water with salinity levels of up to 9 dS m,1, when applied through subirrigation, could be used to successfully produce green peppers and potatoes under semiarid to arid conditions. Copyright © 2002 John Wiley & Sons, Ltd. RÉSUMÉ Comme les ressources en eau douce utilisées poor l'irrigation s'épuisent rapidement, les récentes recherches tentent de mettre l'emphase sur le développement de sources d'eau non-conventionnelles: la réutilisation de l'eau de drainage agricole, l'utilisation des eaux usées municipales et des eaux saumâtres pour l'irrigation des cultures. Lors de pénuries d'eau douce les eaux saumâtres ont été utilisées pour l'irrigation souterraine de maïs, mais la salinité de la couche supérieur du sol a été réduite en raison de la pluie. Dans les régions arides et semi-arides cette méthode s'est limitée à quelques essais seulement. En raison des quantités limitées d'eau de bonne qualité, on ne peut irriguer de vastes étendues agricoles en régions arides. Or, si l'utilisation des eaux saumâtres s'avérait un succès il serait possible d'améliorer les rendements agricoles. Il est donc nécessaire d'évaluer l'utilisation des eaux saumâtres dans les systèmes d'irrigation souterrains en milieu aride. Des expériences en lysimètres au cours de trois saisons, dans le but d'étudier la faisabilité d'utiliser des eaux saumâtres pour l'irrigation souterraine de cultures moyennement sensibles, furent entreprises en 1993 et 1994. Des eaux saumâtres avec des niveaux de salinité de 1, 5 et 9 dS m,1, furent utilisés. En 1993, les effets d'une combinaison factorielle de trois niveaux de salinité, deux profondeurs de nappe phréatique et quatre combinaisons de fertilisation NPK ont servi à évaluer l'accumulation de sel dans un sol initialement non-salin où le poivron vert (Capsicum annuum L.) a été cultivé. Une augmentation graduelle de la salinité de la solution du sol, de la nappe d'eau souterraine jusqu'à la surface, fut évidente. Bien que durant la saison de croissance, la conductivité électrique de la solution du sol (ECsw) n'ait pas atteint un niveau qui aurait pu endommager sérieusement la culture. Ni les différents niveaux de salinité ni la profondeur de la nappe d'eau souterraine n'ont affecté de façon significative les rendements de poivrons. En 1994, deux cultivars de pommes de terre (Solanum tuberosum L.) furent cultivés dans un sol rendu salin, après avoir été irrigué avec une eau d'un niveau de salinité de 3.5 dS m,1, préalablement à la plantation des tubercules. L'accumulation de sel suivit une tendance semblable à celle observée en 1993. Cependant, les niveaux de ECsw enregistrés en 1994 furent plus élevés en raison du taux de salinité initial plus élevé. De plus, une baisse de ECsw fut observée près de la nappe d'eau souterraine dans les lysimètres irrigués avec une eau d'un niveau de salinité de 1 dS m,1. Ni les différents niveaux de salinité ni la profondeur de la nappe d'eau souterraine n'ont affecté de façon significative le rendement de pommes de terre de chacun des cultivars. En 1995, trois cultivars de pommes de terre ont été cultivés dans un soil non salin ainsi que dans un sol rendu salin au moyen d'une eau avec une conductivité électrique de 2 dS m,1. Dans la couche supérieure du sol, un plus important taux d'augmentation de conductivité électrique a été observé dans le sol salin que dans le sol non salin. Il n'y a pas eu de différence significative observée en raison des taux initiaux de salinité ou encore en raison des taux de salinité de l'eau dans le système d'irrigation souterrain. Cette étude suggère que les eaux saumâtres d'un niveau de salinité jusqu'à 9 dS m,1 pourraient être utilisées dans les systèmes d'irrigation souterrains pour la culture du poivron vert et de la pomme de terre en régions semi-arides et arides. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Effect of Sodium Chloride Salinity on Seedling Emergence in Chickpea

JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 3 2002
H. A. Esechie
Although laboratory (Petri dish) germination as an estimate of seed viability is a standard practice, it may not give an accurate prediction of seedling emergence in the field, especially when saline irrigation water is used. Experiments were conducted to investigate seedling emergence in two chickpea cultivars (ILC 482 and Barka local) in response to varied salinity levels and sowing depths. Seeds were sown in potted soil at a depth of 2, 4 or 6 cm. The salinity treatments were 4.6, 8.4 and 12.2 dS m,1. Tap water (0.8 dS m,1) served as the control. Depth of sowing had a significant effect on seedling emergence. Seeds sown 6 cm deep showed the lowest seedling emergence. Similarly, salinity had an adverse effect on seedling emergence. The lowest seedling emergence percentages were obtained at the highest salinity treatment (12.2 dS m,1). The interaction between salinity treatment and seeding depth was significant. Hypocotyl injury was implicated as a possible cause of poor seedling emergence in chickpea under saline water irrigation and was less severe when pre-germinated seeds were used. ILC 482 appeared to be more tolerant to salinity than Barka local, suggesting that breeding programmes involving regional exchange of germplasm may be helpful. Einfluss einer Natriumchloridversalzung auf den Sämlingsaufgang von Kichererbse Obwohl im Laboratorium (Petrischale) die Keimung an Hand einer Abschätzung der Samenkeimkraft als Standard beurteilt wird, kann dies eine nicht zuverlässige Voraussage des Sämlingsaufganges im Feld sein, insbesondere wenn versalztes Bewässerungswasser verwendet wird. Die Experimente wurden durchgeführt, um das Sämlingsauflaufen von zwei Kichererbsenkultivaren (ILC 482 und Barka local) in der Reaktion gegenüber variierten Versalzungskonzentrationen und Aussaattiefen zu untersuchen. Die Samen wurden in Gefäßkulturen mit einer Tiefe von 2, 4 oder 6 cm angesät. Die Versalzungsbehandlungen betrugen 4.6, 8.4 und 12.2 dS m,1. Unversalztes Wasser (0.8 dS m,1) diente als Kontrolle. Die Aussaattiefe hatte einen signifikanten Einfluss auf das Auflaufen der Sämlinge. Samen mit einer 6 cm Tiefe Ansaat hatten den schlechtesten Auflauf. Entsprechend zeigte auch die Versalzung einen ungünstigen Einfluss auf den Sämlingsaufgang. Die schlechteste Keimlingsaufgangsrate wurde bei der höchsten Versalzungsbehandlung (12.2 dS m,1) gefunden. Die Interaktion zwischen Versalzungsbehandlungen und Saattiefe war signifikant. Die Hypokotytbeschädigung wird als eine mögliche Ursache der schwachen Auflaufraten bei Kichererbse unter dem Einfluss versalzten Bewässerungswassers erklärt; die Wirkung war weniger schwer, wenn vorgekeimte Samen verwendet wurden. ILC 482 scheint toleranter gegenüber Versalzung zu sein als Barka local; es erscheint zweckmäßig, Zuchtprogramme unter Verwendung regionaler Genotypen durchzuführen. [source]

Plant,Water Relations of Kidney Bean Plants Treated with NaCl and Foliarly Applied Glycinebetaine

JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 2 2002
C. M. L. Lopez
Salinity is at present one of the most serious environmental problems influencing crop growth. It has been extensively demonstrated that salinity affects several physiological processes in the plant, including the plant,water relations of most salt-sensitive crops species. In this study, the effects of salinity on the plant,water relations of kidney bean (Phaseolus vulgaris L.) and the possibility that foliarly applied glycinebetaine improves these water relations are examined. Kidney bean plants were grown in a greenhouse and treated with 0, 30, 50 and 100 mM NaCl, combined with 0, 10 and 30 mM glycinebetaine in foliar applications. Increased salinity levels decreased stomatal conductance, photosynthetic rate, transpiration and leaf relative water content in the 30, 50 and 100 mM treatments relative to the control treatment. Glycinebetaine applications of 10 mM increased stomatal conductance at 50 mM NaCl, ameliorating significantly the effect of salinity on water relations through increases in the leaf relative water content. At 100 mM NaCl, 30 mM glycinebetaine applications in particular contributed to osmotic stress, and had an adverse effect on plants. Our experiment suggests that glycinebetaine can be used as an alternative treatment to reduce the effects of salt stress on the water relations of salt-sensitive plants, but only to limited salinity levels. Furthermore, the improvement in the water status of kidney beans was dose dependent, suggesting that the concentration of glycinebetaine essential for the survival of salt-sensitive plants is species specific and must be determined individually for each plant species. Pflanzen,Wasser-Beziehungen von NaCl-behandelten und mit Glycinbetain besprühten Blättern von Gartenbohnenpflanzen Versalzung ist zur Zeit eine der am meisten wirksamen Umweltprobleme im Hinblick auf das Wachstum von Kulturpflanzen. Es hat umfangreiche Untersuchungen gegeben, die Versalzungswirkungen in ihrem Einfluss auf zahlreiche physiologische Vorgänge in der Pflanze zu untersuchen; hierbei wurden auch die Pflanzen,Wasser-Beziehungen von hochsalzempfindlichen Pflanzenarten berück-sichtigt. In dieser Untersuchung wurden die Einflüsse der Versalzung auf die Pflanzen,Wasser-Beziehungen bei Buschbohnen (Phaseolus vulgaris L.) und die Möglichkeit über Blattbesprühungen mit Glycinbetain die Wasser-Beziehungen zu verbessern, untersucht. Die Buschbohnen wurden im Gewächshaus angezogen und mit 0, 30, 50 mM NaCl in Kombination mit 0, 10, 30 mM Glycinbetain Blattbehandlungen angezogen. Eine Erhöhung der Versalzung führte zu einer Abnahme der stomatären Konduktanz, der Photosyntheserate, der Transpiration und des relativen Blattwassergehaltes bei den Behandlungen mit 30, 50 und 100 mM im Vergleich zur Kontrolle. Glysinbetainanwendungen von 10mM erhöhten die stomatäre Konduktanz bei 50 mM NaCl und verbesserten signifikant den ungünstigen Einfluss der Versalzung auf die Wasser-Beziehungen über eine Erhöhung des relativen Blattwassergehaltes. Verwendung von 100 mM NaCl und 30 mM GB trug zu dem osmotischen Streß durch Versalzung bei und hatten einen ungünstigen Einfluss auf die Pflanzen. Unser Experiment weist darauf hin, dass Glycinbetain eine alternative Möglichkeit ist, um die Einflüsse des Salzstresses auf die Wasser-Beziehungen von salzempfindlichen Pflanzen abzuschwächen; es bestehen aber Begrenzungen bezüglich des Versalzungsgrades, bei denen eine günstige Wirkung nachgewiesen werden kann. Ausserdem ist die Verbesserung im Wasserzustand der Buschbohnen von der Anwendungsstärke abhängig, so dass die Konzentration von GB wesentlich für das Überleben der salzempfindlichen Pflanzenart spezifisch ist und für jede Pflanzenart untersucht werden. [source]

Positive and negative consequences of salinity stress for the growth and reproduction of the clonal plant, Iris hexagona

JOURNAL OF ECOLOGY, Issue 5 2003
Peter A. Van Zandt
Summary 1Salinization is a growing environmental stress in wetland ecosystems world-wide. Several models have been proposed that predict clonal plant responses to stress, including that environmental stress stimulates sexual reproduction. 2We conducted a common-garden experiment to investigate the effects of salinity on 10 natural populations of Iris hexagona, a clonal perennial endemic to freshwater and brackish wetlands of the North American Gulf Coast. 3Salinity reduced vegetative growth but either increased or had neutral effects on sexual reproduction, consistent with the clonal stress hypothesis. Salinity of 4 µg g,1 more than doubled the number of seeds produced compared with freshwater controls, but flower number and seed mass were unaffected. 4Salinity reduced total below-ground mass by nearly 50% compared with controls, with no significant change in rhizome numbers. 5Plants from 10 randomly selected I. hexagona populations differed dramatically in growth and reproduction, independent of salinity. Total biomass that accumulated over the 20-month experiment ranged across all treatments from 52 to 892 g, and flower numbers varied from 2.3 to 11.3 per replicate. 6Populations did not respond differently to salinity, except with respect to above- : below-ground ratios, thus providing no conclusive evidence for local adaptation to salinity stress. 7Our results concur with published models of plant reproductive strategies in variable environments, in that environmental stress stimulated sexual reproduction at the expense of growth. However, these models do not predict the observed sharp decline in seed production at near lethal salinity levels. [source]

Effects of reduced salinities on growth, food conversion efficiency and osmoregulatory status in the spotted wolffish

JOURNAL OF FISH BIOLOGY, Issue 2 2001
A. Foss
No significant differences in mean mass between groups were found at any time in spotted wolffish Anarhichas minor, mean (±S.D.) initial mass 76 (±21) g, reared at salinities of 12, 17, 25 and 34, for 12 weeks at 8° C. Salinity did not have a significant effect on daily feeding rates, total food consumption, food conversion efficiency and protein efficiency ratio. Growth trajectories varied between groups, but no overall difference in growth was found. Plasma osmolality and plasma chloride levels decreased with salinity in a 48 h abrupt exposure trial, and in the growth experiment the low salinity groups (12 and 17,) exhibited significantly lower values compared with 25 and 34,. The decrease was moderate and concentrations were well within the range described for other marine species. The results indicate that the spotted wolffish is a strong osmoregulator which could be reared at various salinity levels. [source]

Assessing the Suitability of Various Physiological Traits to Screen Wheat Genotypes for Salt Tolerance

JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 9 2007
Salah E. El-Hendawy
Abstract Success of improving the salt tolerance of genotypes requires effective and reliable screening traits in breeding programs. The objective was to assess the suitability of various physiological traits to screen wheat genotypes for salt tolerance. Thirteen wheat genotypes from Egypt, Germany, Australia and India were grown in soil with two salinity levels (control and 150 mmol/L NaCl) in a greenhouse. The physiological traits (ion contents in leaves and stems, i.e. Na+, Cl,, K+, Ca2+), the ratios of K+/Na+ and Ca+/Na+ in the leaves and stems, net photosynthesis rate, stomatal conductance, transpiration rate, chlorophyll content (SPAD value), and leaf water relations, were measured at different growth stages. The physiological traits except for Na+ and Cl, in stems and the leaf transpiration rate at 150 mmol/L NaCl showed a significant genotypic variation, indicating that the traits that have a significant genotypic variation may be possibly used as screening criteria. According to the analysis of linear regression of the scores of the physiological traits against those of grain yield, however, the physiological traits of Ca2+ and Ca2+/Na+ at 45 d and final harvest with the greatest genotypic variation were ranked at the top. From a practical and economic point of view, SPAD value should be considered to be used as screening criteria and/or there is a need to develop a quick and practical approach to determine Ca2+ in plant tissues. [source]

CYST,THECA RELATIONSHIP, LIFE CYCLE, AND EFFECTS OF TEMPERATURE AND SALINITY ON THE CYST MORPHOLOGY OF GONYAULAX BALTICA SP.

The Effects of Temperature and Salinity on Early Life Stages of Black Sea Bass Centropristis striata

Tolerance of Pinus taeda and Pinus serotina to low salinity and flooding: Implications for equilibrium vegetation dynamics

JOURNAL OF VEGETATION SCIENCE, Issue 1 2008
Benjamin Poulter
Abstract Questions: 1. Do pine seedlings in estuarine environments display discrete or continuous ranges of physiological tolerance to flooding and salinity? 2. What is the tolerance of Pinus taeda and P. serotina to low salinity and varying hydrologic conditions? 3. Are the assumptions for ecological equilibrium met for modeling plant community migration in response to sea-level rise? Location: Albemarle Peninsula, North Carolina, USA. Methods: In situ observations were made to quantify natural pine regeneration and grass cover along a salinity stress gradient (from marsh, dying or dead forest, to healthy forest). A full-factorial greenhouse experiment was set up to investigate mortality and carbon allocation of Pinus taeda and P. serotina to low-salinity conditions and two hydrology treatments over 6 months. Treatments consisted of freshwater and two salinity levels (4 ppt and 8 ppt) under either permanently flooded or periodically flushed hydrologic conditions. Results: Natural pine regeneration was common (5,12 seedlings per m2) in moderate to well-drained soils where salinity concentrations were below ca. 3.5 ppt. Pine regeneration was generally absent in flooded soils, and cumulative mortality was 100% for 4 and 8 ppt salinity levels under flooded conditions in the greenhouse study. Under weekly flushing conditions, mortality was not significantly different between 0 and 4 ppt, confirming field observations. Biomass accumulation was higher for P. taeda, but for both pine species, the root to shoot ratio was suppressed under the 8 ppt drained treatment, reflecting increased below-ground stress. Conclusions: While Pinus taeda and P. serotina are commonly found in estuarine ecosystems, these species display a range of physiological tolerance to low-salinity conditions. Our results suggest that the rate of forest migration may lag relative to gradual sea-level rise and concomitant alterations in hydrology and salinity. Current bioclimate or landscape simulation models assume discrete thresholds in the range of plant tolerance to stress, especially in coastal environments, and consequently, they may overestimate the rate, extent, and timing of plant community response to sea-level rise. [source]

Vegetation change from chronic stress events: Detection of the effects of tide gate removal and long-term drought on a tidal marsh

JOURNAL OF VEGETATION SCIENCE, Issue 3 2007
Paul R. Wetzel
Godfrey & Wooten (1979, 1981) Abstract Question: Chronic stress events are defined as disturbance events that exceed the lifespan of the dominant plant species, fluctuate in intensity and lack abruptness or physical destruction of biomass. Can the effects of chronic stress events be measured on vegetation communities? Did two chronic stress events, the removal of a tide gate and a four year drought, cause a temporary or permanent shift in the vegetation communities of a tidal marsh? Location: Tidal marsh in southeastern United States. Methods: Change in species composition and dominance and community change on a landscape level salinity gradient were measured between time periods ranging from four months to seven years to construct a statistical baseline reference community at freshwater, oligohaline, and mesohaline sections of a tidal marsh. Statistical shifts in the plant community were defined as changes in the plant community that fell outside of the defined baseline reference community. Results: Plant community changes outside of the reference community occurred in 13 out of 378 community comparisons. Removal of the tide gate had a greater effect on interstitial salinity levels than the drought and was most intense in the oligohaline marsh, where between 20 to 45% of the freshwa-ter/oligohaline community types permanently converted to oligohaline community types. However, community shifts in the freshwater and oligohaline marsh induced by the drought were temporary, lasting from 1 to 3+ years. Neither chronic stress event permanently altered the mesohaline plant communities. Conclusion: The effects of chronic stress events could be detected; an extended historical record of vegetation change (18 years) was necessary to identify community shifts outside of a reference condition of the community and to determine if those shifts were permanent or temporary. [source]

Differences in efficient metabolite management and nutrient metabolic regulation between wild and cultivated barley grown at high salinity

PLANT BIOLOGY, Issue 4 2010
Sabah Yousfi
Abstract Physiological and biochemical responses of Hordeum maritimum and H. vulgare to salt stress were studied over a 60-h period. Growth at increasing salinity levels (0, 100, 200 and 300 mM NaCl) was assessed in hydroponic culture. H. maritimum was shown to be a true halophyte via its typical behaviour at high salinity. Shoot growth of cultivated barley was gradually reduced with increasing salinity, whereas that of wild barley was enhanced at 100 and 200 mm NaCl then slightly reduced at 300 mM NaCl. The higher salt tolerance of H. maritimum as compared to H. vulgare was due to its higher capacity to maintain cell turgor under severe salinity. Furthermore, H. maritimum exhibited fine regulation of Na+ transport from roots to shoots and, unlike H. vulgare, it accumulated less Na+ in shoots than in roots. In addition, H. maritimum can accumulate more Na+ than K+ in both roots and shoots without the appearance of toxicity symptoms, indicating that Na+ was well compartmentalized within cells and substituted K+ in osmotic adjustment. The higher degree of salt tolerance of H. maritimum is further demonstrated by its economic strategy: at moderate salt treatment (100 mm NaCl), it used inorganic solutes (such as Na+) for osmotic adjustment and kept organic solutes and a large part of the K+ for metabolic activities. Indeed, K+ use efficiency in H. maritimum was about twofold that in H. vulgare; the former started to use organic solutes as osmotica only at high salinity (200 and 300 mm NaCl). These results suggest that the differences in salt tolerance between H. maritimum and H. vulgare are partly due to (i) differences in control of Na+ transport from roots to shoots, and (ii) H. maritimum uses Na+ as an osmoticum instead of K+ and organic solutes. These factors are differently reflected in growth. [source]

Carbon isotope discrimination: potential for screening salinity tolerance in rice at the seedling stage using hydroponics

PLANT BREEDING, Issue 3 2005
R. Shaheen
Abstract Rice is a moderately salt-sensitive crop species and soil salinity is the single most widespread soil toxicity problem lacing rice production. The quantification of salinity resistance poses serious problems in the field because of climatic factors and field heterogeneity. In the present study. rice germplasm obtained from the International Rice Research Institute (IRRI). Philippines, was screened in a naturally lit (11 h daylight) glasshouse-based hydroponics unit at two salinity levels (4 and 6 dS/m), Phenotypic performance based on survival of tolerant, moderately tolerant and susceptible isogenic lines along with tolerant and susceptible parents was evaluated after 10 and 13 days of salt stress. Plants were harvested after second scoring and carbon isotope discrimination in the leaves (A) was measured. ,1 ranged from 19.5 to 22.9%, A highly significant negative correlation (r =,0.95. P < 0.001) between , and visual scoring was observed. Data indicated the potential of using , as a physiological indicator for salinity tolerance in rice seedlings grown in hydroponics. [source]

Effects of salinity levels on proteome of Suaeda aegyptiaca leaves

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 8 2006
Hossein Askari
Abstract Saline soils are the major problem of cultivated lands of Iran. Suaeda aegyptiaca is a salt-tolerant plant (halophytes) that grow naturally in salt-affected areas of Iran. We have employed proteomics to identify the mechanisms of salt responsiveness in leaves of S.,aegyptiaca grown under different salt concentrations. Ten-day-old plants were treated with 0, 150, 300, 450, and 600,mM NaCl. After 30,days of treatment, leaf samples were collected and analyzed using 2-D-PAGE. Out of 700,protein spots reproducible detected within replications, 102,spots showed significant response to salt treatment compared to 0,mM,NaCl. We analyzed expression pattern of salt-responsive proteins using a hierarchical and two nonhierarchical (Fuzzy ART and SOM) statistical methods and concluded that Fuzzy ART is the superior method. Forty proteins of 12,different expression groups were analyzed using LC/MS/MS. Of these, 27,protein spots were identified including proteins involved in oxidative stress tolerance, glycinebetain synthesis, cytoskeleton remodeling, photosynthesis, ATP production, protein degradation, cyanide detoxification, and chaperone activities. The expression pattern of these proteins and their possible roles in the adaptation of S.,aegyptiaca to salinity is discussed. [source]

Reducing salinity and organic contaminants in the Pearl Harbor dredged material using soil amendments and plants

Effects of salt stress on purslane (Portulaca oleracea) nutrition

Effects of salinity on the growth and proximate composition of selected tropical marine periphytic diatoms and cyanobacteria

AQUACULTURE RESEARCH, Issue 9 2010
Helena Khatoon
Abstract Marine periphytic cyanobacteria and diatoms have been examined as a potential source of feed supplement for rearing aquatic larvae in the aquaculture industry. Culture of the periphytic diatom Amphora sp., Navicula sp., Cymbella sp. and the cyanobacteria Oscillatoria sp. at different salinities showed significant changes in biomass and specific growth rates. Diatoms growth was significantly higher at 35 g L,1, while for cyanobacteria growth was better at 25 g L,1. Significantly higher levels of protein and lipid were found in diatoms at low salinities (15,25 g L,1) and an increase in carbohydrate at high salinities (30,35 g L,1). Conversely, cyanobacteria showed a significantly higher lipid content at 30,35 g L,1 compared with other salinity levels but no significant changes were observed in the protein and carbohydrate contents at different salinity levels. The present findings can be taken into consideration when culturing marine periphytic Amphora sp., Navicula sp., Cymbella sp. and Oscillatoria sp. to provide appropriate levels of protein, lipid and carbohydrate as feed supplement as well as for bioremediation in aquaculture. [source]

Effect of salinity on survival, growth, oxygen consumption and ammonia-N excretion of juvenile whiteleg shrimp, Litopenaeus vannamei

AQUACULTURE RESEARCH, Issue 12 2009
Peidong Zhang
Abstract In this study, we tested the lower salinity tolerance of juvenile shrimps (Litopenaeus vannamei) at a relatively low temperature (20 °C). In the first of two laboratory experiments, we first abruptly transferred shrimps (6.91 ± 0.05 g wet weight, mean ± SE) from the rearing salinity (35 000 mg L,1) to salinities of 5000, 15 000, 25 000, 35 000 (control) and 40 000 mg L,1 at 20 °C. The survival of L. vannamei juvenile was not affected by salinities from 15 000 to 40 000 mg L,1 during the 96-h exposure periods. Shrimps exposed to 5000 mg L,1 were significantly affected by salinity, with a survival of 12.5% after 96 h. The 24-, 48- and 96-h lethal salinity for 50% (LS50) were 7020, 8510 and 9540 mg L,1 respectively. In the second experiment, shrimps (5.47 ± 0.09 g wet weight, mean ± SE) were acclimatized to the different salinity levels (5000, 15 000, 25 000, 35 000 and 40 000 mg L,1) and then maintained for 30 days at 20 °C. Results showed that the survival was significantly lower at 5000 mg L,1 than at other salinity levels, but the final wet weight under 5000 mg L,1 treatment was significantly higher than those under other treatments (P<0.05). Feed intake (FI) of shrimp under 5000 mg L,1 was significantly lower than those of shrimp under 150 00,40 000 mg L,1; food conversion efficiency (FCE), however, showed a contrasting change (P<0.05). Furthermore, salinity significantly influenced the oxygen consumption rates, ammonia-N excretion rates and the O/N ratio of test shrimps (P<0.05). The results obtained in our work provide evidence that L. vannamei juveniles have limited capacity to tolerate salinities <10 000 mg L,1 at a relatively low temperature (20 °C). Results also show that L. vannamei juvenile can recover from the abrupt salinity change between 15 000 and 40 000 mg L,1 within 24 h. [source]

Effect of salinity on carrying capacity of adult Nile tilapia Oreochromis niloticus L. in recirculating systems

Diversity and salt tolerance of native Acacia rhizobia isolated from saline and non-saline soils

AUSTRAL ECOLOGY, Issue 8 2009
PETER H. THRALL
Abstract Re-establishing native vegetation in stressed soils is of considerable importance in many parts of the world, leading to significant interest in using plant,soil symbiont interactions to increase the cost-effectiveness of large-scale restoration. However, effective use of soil microbes in revegetation requires knowledge of how microbe communities vary along environmental stress gradients, as well as how such variation relates to symbiont effectiveness. In Australia, shrubby legumes dominate many ecosystems where dryland salinity is a major issue, and improving plant establishment in saline soils is a priority of regional management agencies. In this study, strains of rhizobial bacteria were isolated from a range of Acacia spp. growing in saline and non-saline soils. Replicates of each strain were grown under several salinity levels in liquid culture and characterized for growth and salt tolerance. Genetic characterization of rhizobia showed considerable variation among strains, with salt tolerance and growth generally higher in rhizobial populations derived from more saline soils. These strains showed markedly different genetic profiles and generic affiliations to those from more temperate soils, suggesting community differentiation in relation to salt stress. The identification of novel genomic species from saline soils suggests that the diversity of rhizobia associated with Australian Acacia spp. is significantly greater than previously described. Overall, the ability of some symbiotically effective strains to tolerate high salinity is promising with regard to improving host plant re-establishment in these soils. [source]