Partitioning Of Na Research Articles

High Sodium Solubility in Magnesiowüstite in Iron‐Rich Deep Lower Mantle

Abstract(Mg,Fe)O ferropericlase‐magnesiowüstite has been proposed to host the majority of Earth's sodium, but the mechanism and capacity for incorporating the alkali cation remain unclear. In this work, experiments in the laser‐heated diamond anvil cell and first‐principles calculations determine the solubility of sodium and favorability of sodium incorporation in iron‐rich magnesiowüstite relative to (Mg,Fe)SiO3 bridgmanite. Reaction of Mg/(Mg + Fe) (Mg#) 55 and 28 olivine with NaCl at 33–128 GPa and 1600–3000 K produces iron‐rich magnesiowüstite containing several percent sodium, while iron‐rich bridgmanite contains little to no detectable sodium. In sodium‐saturated magnesiowüstite, sodium number [Na/(Na + Mg + Fe)] is 2–5 atomic percent at pressures below 60 GPa and drastically increases to 10–20 atomic percent at deep lower mantle pressures. For these two compositions, there is no significant dependence of the results on Mg#. Our calculations not only show consistent results with experiments but further indicate that such an increase in solubility and partitioning of Na into magnesiowüstite is driven by the spin transition in iron. These results provide fundamental constraints on the crystal chemistry of sodium at lower‐mantle conditions. If the sodium capacity of (Mg,Fe)O is not strongly dependent on Mg#, (Mg,Fe)O in the lower mantle may have the capacity to store the entire sodium budget of the Earth.

Genome-wide identification and expression analysis of Na+/H+antiporter (NHX) genes in tomato under salt stress.

Plant Na +/H + antiporter (NHX) genes enhance salt tolerance by preventing excessive Na+ accumulation in the cytosol through partitioning of Na+ ions into vacuoles or extracellular transport across the plasma membrane. However, there is limited detailed information regarding the salt stress responsive SlNHXs in the most recent tomato genome. We investigated the role of this gene family's expression patterns in the open flower tissues under salt shock in Solanum lycopersicum using a genome-wide approach. A total of seven putative SlNHX genes located on chromosomes 1, 4, 6, and 10 were identified, but no ortholog of the NHX5 gene was identified in the tomato genome. Phylogenetic analysis revealed that these genes are divided into three different groups. SlNHX proteins with 10-12 transmembrane domains were hypothetically localized in vacuoles or cell membranes. Promoter analysis revealed that SlNHX6 and SlNHX8 are involved with the stress-related MeJA hormone in response to salt stress signaling. The structural motif analysis of SlNHX1, -2, -3, -4, and -6 proteins showed that they have highly conserved amiloride binding sites. The protein-protein network revealed that SlNHX7 and SlNHX8 interact physically with Salt Overly Sensitive (SOS) pathway proteins. Transcriptome analysis demonstrated that the SlNHX2 and SlNHX6 genes were substantially expressed in the open flower tissues. Moreover, quantitative PCR analysis indicated that all SlNHX genes, particularly SlNHX6 and SlNHX8, are significantly upregulated by salt shock in the open flower tissues. Our results provide an updated framework for future genetic research and development of breeding strategies against salt stress in the tomato.

Effect of Zinc and Nickel Treatments on Improvement of the Osmotic Defense System of Wheat Plant Under Salinity Stress

The present experiments were performed to determine the effects of Zn (20 µM and 200 µM) and Ni (1 µM and 100 µM) on the growth and metabolic activities in the roots, shoots, and spikes of wheat (<i>Triticum aestivum</i> L.) cv. Gimiza 11 grown under different salinity conditions. In addition to identifying the osmotic tolerance of wheat, the roles of Zn and Ni in alleviating osmotic stress were examined. The root was the organ most sensitive to osmotic stress, whereas the shoot was the most resistant, and the spike was the intermediate. These three organs negatively responded to increasing osmotic stress levels, as fresh and dry matter decreased, and related biochemical parameters were adversely affected. However, fresh and dry matter were generally elevated when plants were supplemented with Zn or Ni under increasing osmotic stress. The sensitivity of roots was associated with depletion in the concentrations of sugars and free proline, whereas soluble protein and amino acid levels were increased. The stress tolerance of shoots and spikes was accompanied by an increase in soluble sugars, soluble proteins, and proline, while amino acid levels increased in spikes only. The Na<sup>+</sup> and K<sup>+</sup> content in wheat plants increased with increasing NaCl-induced osmotic stress levels. In turn, the accumulation and partitioning of Na<sup>+</sup> and K<sup>+</sup> did not vary among the three organs, both at different salt concentrations and between Zn or Ni treatments. Moreover, the present results show that the concentrations of anthocyanins, flavonoids, and l-ascorbic acid increased under exposure to osmotic stress and did not change significantly under Zn or Ni treatments.

Silicon nutrition improves growth of salt-stressed wheat by modulating flows and partitioning of Na+, Cl− and mineral ions

Silicon (Si) is reported to improve salt stress tolerance of cereals, but little is known about the effects of Si on flows and partitioning of sodium (Na+), chloride (Cl−), and essential mineral ions at the tissue and cellular level. Wheat (Triticum aestivum L.) was exposed to 200 mM NaCl for 30 d in hydroponics, with or without 2 mM Si. X-ray microanalysis coupled with scanning electron microscopy (SEM) was used to quantify the cell-specific ion profiles across root and leaf cells, paralleled by measurements of wheat growth and physiological responses. Under salt stress, higher Na+ and Cl− concentrations were detected in root epidermal, cortical and stelar cells, eventually increasing their concentrations in different leaf cells, being highest in the epidermal cells and lowest in the vascular bundle cells. The potassium (K+) and magnesium (Mg2+) profiles were generally opposite to those of Na+ and Cl−. NaCl-dependent deregulation of essential nutrient homeostasis and excessive toxic ions accumulation in leaves was correlated with enhanced electrolyte leakage index (ELI), decreased chlorophyll contents, photosynthesis and other physiological parameters, and ultimately hampered plant growth. Conversely, Si addition improved the growth and physiological performance of salinized wheat by reducing Na+ and Cl− concentration in root epidermal and cortical cells, and it improved root uptake and storage of K+ and Mg2+ ions and their loading into xylem for distribution to shoots. These results suggest that Si-mediated inhibition of Na+ uptake, maintained nutrient homeostasis and improved physiological parameters to contribute to wheat growth improvement under salt stress.

Planktonic foraminiferal spine versus shell carbonate Na incorporation in relation to salinity

Abstract. Sea surface salinity is one of the most important parameters to reconstruct in paleoclimatology, reflecting amongst other things the hydrological cycle, paleodensity, ice volume, and regional and global circulation of water masses. Recent culture studies and a Red Sea field study revealed a significant positive relation between salinity and Na incorporation within benthic and planktonic foraminiferal shells. However, these studies reported varying partitioning of Na between and within the same species. The latter could be associated with ontogenetic variations, most likely spine loss. Varying Na concentrations were observed in different parts of foraminiferal shells, with spines and regions close to the primary organic sheet being especially enriched in Na. In this study, we unravel the Na composition of different components of the planktonic foraminiferal shell wall using electron probe micro-analysis (EPMA) and solution ICP-MS. A model is presented to interpret EPMA data for spines and spine bases to quantitatively assess differences in composition and contribution to whole-shell Na∕Ca signals. The same model can also be applied to other spatial inhomogeneities observed in foraminiferal shell chemistry, like elemental (e.g., Mg, Na, S) banding and/or hotspots. The relative contribution of shell carbonate, organic linings, spines and spine bases to whole-shell Na chemistry is considered quantitatively. This study shows that whereas the high Na areas may be susceptible to taphonomic alterations, the Na chemistry of the shell itself seems relatively robust. Comparing both shell and spine Na∕Ca values with salinity shows that shell chemistry records salinity, albeit with a very modest slope.

Synthetic fluid inclusions XXI. Partitioning of Na and K between liquid and vapor in the H2O-NaCl-KCl system at 600–800 °C and 500–1000 bars

The synthetic fluid inclusion technique was used to determine the partitioning behavior (distribution constant) of Na and K between coexisting liquid and vapor phases in the H2O-NaCl-KCl system at 500–1000 bars, 600–800 °C, and for fluids with initial Na/K molar ratios of 3:1, 2:1, 1:1, 1:2 and 1:3. Compositions of coexisting liquid and vapor phases in the binary H2O-KCl system were also determined. Distribution constants for sodium (DNaL/V) and potassium (DKL/V) were calculated from salinities of the synthetic fluid inclusions determined by microthermometry. For a given temperature, pressure and molar Na/K ratio, the distribution constants for Na and K between liquid and vapor are essentially equal, with only a slight preference for Na to partition into the vapor phase and for K to partition into the liquid phase. As such, fluid phase immiscibility and the subsequent physical separation of the liquid and vapor phases owing to buoyancy differences are unlikely to lead to fluids with variable Na/K in different parts of magmatic-hydrothermal systems. The liquid–vapor partitioning behavior obtained here is consistent with previously determined Na/K partitioning between granitic melts and exsolved magmatic aqueous fluids, and with compositions of hydrothermal fluids and associated feldspars in potassic alteration zones of porphyry copper deposits.

Na Partitioning During Thermomechanical Processing of an Mg-Sn-Zn-Na Alloy

Microstructural characterization was used to examine the changes that occur in an Mg-6Sn-5Zn-0.3Na alloy from casting to extrusion at either 623 K or 723 K (350 °C or 450 °C) followed by artificial aging at 473 K (200 °C). In particular, the partitioning of Na was examined at each step using STEM-EDS mapping. Na atoms were found to preferentially partition to the Mg-Zn phase when present. After extrusion, when no Mg-Zn was observed, the spherical Mg2Sn particles were found to be enriched in Na, particularly at the higher extrusion temperature. Artificial aging following extrusion resulted in a change in Na partitioning, and a coarse distribution of Mg-Zn precipitate rods. Na microadditions led to a high as-extruded hardness, but a significant tension–compression yield asymmetry was still observed at room temperature. The compressive yield strength was found to decrease significantly after 1000 hours of aging.

Vegetative performance, leaf water potential, and partitioning of minerals and soluble sugars: Traits for ranking the NaCl-tolerance of tomato genotypes?

This study addresses the physiological response of four tomato genotypes with distinct sensitivity to high NaCl concentrations, with the aim of identifying physiological traits to rank the genotypes’ sensitivity to salt stress. The central hypothesis was that tomato genotypes grown in saline environments show a characteristic salinity-triggered absorption and translocation of ions, leading to a distinct distribution pattern of Na, K, and soluble sugars. Experiments were conducted on two commercial cultivars: one assumed to be sensitive (Solanum lycopersicum L. F1 hybrid Harzfeuer) and one known to be tolerant (S. lycopersicum L. var. edkawi) to high salt concentrations. Furthermore, two wild salt-tolerant relatives (S. pennellii and S. lycopersicum var. cerasiforme) were selected. Based on our results regarding vegetative performance and partitioning of Na, K, glucose, fructose, and sucrose, it is possible to classify the genotype S. lycopersicum F1 hybrid Harzfeuer as moderately sensitive to salt stress and the genotypes S. lycopersicum var. edkawi, S. lycopersicum var. cerasiforme, and S. pennellii as moderately resistant to 210 mM NaCl. Calculations of the percentage of modification revealed non-specific genotype responses for the amount of sodium in roots and leaves, as well as the sucrose concentration and the osmotic potential of leaves. As shown, the salt-induced changes in potassium levels in leaves, and glucose concentration in roots might be used as additional traits to discriminate genotypes regarding their salt-sensitivity. These parameters might be useful when comparisons of fruit production or vegetative performance provide no conclusive indication e.g. due to the distinct growth habits of commercial cultivars selected for fruit productivity and native genotypes having a stronger vegetative development. However, additional studies should be conducted to evaluate a large number of genotypes differing in their NaCl tolerance. Furthermore, plant responses considering the dynamic source-sink relations due to fruit load needs to be considered.

The Na+/H+ exchanger SOS1 controls extrusion and distribution of Na+ in tomato plants under salinity conditions

Maintaining a high K+/Na+ ratio in the cell cytosol, along with the transport processes implicated in the xylem and phloem loading/unloading of Na+ in plants (long-distance transport) are key aspects in plant salt tolerance. The Ca2+-dependent SOS pathway regulating Na+ and K+ homeostasis and long-distance Na+ transport has been reported in Arabidopsis. However, Arabidopsis might not be the best model to analyze the involvement of the SOS pathway in long-distance Na+ transport due to the very short stem of these plants which do not allow a precise dissection of the relative content of Na+ in stem versus leaf. This separation would be critical to assess the role of SOS1 in xylem loading/unloading, Na+ export by roots, retention in stems and the differential distribution/accumulation in old leaves. Towards this goal, tomato might represent a superior model due to its anatomical structure and agricultural significance. We recently demonstrated the key role played by the plasma membrane Na+/H+ antiporter SlSOS1 in salt tolerance in tomato by maintaining ion homeostasis under salinity stress and in the partitioning of Na+ in plant organs.

Partitioning of Na between olivine and melt: An experimental study with application to the formation of meteoritic Na 2O-rich chondrule glass and refractory forsterite grains

We report experimentally determined 1 atm olivine/melt D Na partitioning data for low f O2, a variety of melt compositions and a temperature range of 1325–1522 °C. We demonstrated that high-current electron microprobe analyses (EPMA, I = 500 nA, 600 s on the peak) allow quantitative determination of Na 2O in olivine down to ∼10 μg/g. The mean olivine/melt D Na from 12 experimental runs is 0.0031 ± 0.0007 (1 σ). This is the recommended value for low pressures and a wide range of natural compositions. This result is applied to the problem of the origin of alkalis in chondrules and the formation of chondritic refractory forsterite grains. The data on Semarkona (LL3.0) chondrules show that Na 2O is primordial and was present during olivine crystallization. For refractory forsterite grains from Murchison (CM2), we demonstrate that high CaO contents are not a result of equilibration with Na 2O-rich melts, but require high activities of CaO during their formation.

Salt stress response in tomato beyond the salinity tolerance threshold

Crop salt tolerance is generally assessed as the relative yield response to increasing root zone salinity, expressed as soil (EC e) or irrigation water (EC w) electrical conductivity. Alternatively, the dynamic process of salt accumulation into the shoot relative to the shoot biomass has also been considered as a tolerance index. These relationships are graphically represented by two intersecting linear regions, which identify (1) a specific threshold tolerance, at which yield begins to decrease, and (2) a declining region, which defines the yield reduction rate. Although the salinity threshold is intuitively a critical parameter for establishing plant salt tolerance, we focused our interest on physiological modifications that may occur in the plant at salinity higher than the so-called tolerance threshold. For this purpose, we exposed hydroponically grown tomato plants to eight different salinity levels (EC = 2.5 (non-salinized control); 4.2; 6.0; 7.8; 9.6; 11.4; 13.2; 15.0 dS m −1). Based on biomass production, water relations, leaf ions accumulation, leaf and root abscisic acid and stomatal conductance measurements, we were able to identify a specific EC value (approximately 9.6 dS m −1) at which a sharp increase of the shoot and root ABA levels coincided with (1) a decreased sensitivity of stomatal response to ABA; (2) a different partitioning of Na + ions between young and mature leaves; (3) a remarkable increase of the root-to-shoot ratio. The specificity and functional significance of this response in salt stress adaptation is discussed.

Metabolic responses to salt stress in cell suspension cultures of sensitive and resistant Citrus

SummaryThe acquisition of resistance to salt stress was investigated in cell suspension cultures of two Citrus cultivars, Citrus hybrid cv. ‘Carvalhal’ and Citrus sinensis cv. ‘Valencia late’. The metabolic responses in terms of scavenging enzyme activities (e.g., superoxide dismutase, catalase and guaiacol peroxidase), partitioning of Na+, Cl– and K+ ions, and proline accumulation were investigated in relation to growth and salt damage at the cellular level. These two cell lines use different metabolic and cell biochemical strategies to tolerate salt stress. The ‘Carvalhal’ cell line displayed a salt-resistant behaviour, even at high salt concentrations.This salt-resistance behaviour operated primarily by impeding the uptake of Na+ and Cl– ions combined with intracellular proline accumulation and a high level of scavenging of reactive oxygen species (ROS). On the other hand, the cv. ‘Valencia late’ appeared to be salt-sensitive. Proline accumulation can be used as an indicator of the salt stress imposed on Citrus cell lines under the conditions used here.

Significance of Na+ and K+ for Sustained Hydration of Organ Tissues in Ecologically Distinct Halophytes of the Family Chenopodiaceae

The contents of Na+, K+, water, and dry matter were measured in leaves and roots of euhalophytes Salicornia europaea L. and Climacoptera lanata (Pall.) Botsch featuring succulent and xeromorphic cell structures, respectively, as well as in saltbush Atriplex micrantha C.A. Mey, a halophyte having bladder-like salt glands on their leaves. All three species were able to accumulate Na+ in their tissues. The Na+ content in organs increased with elevation of NaCl concentration in the substrate, the concentrations of Na+ being higher in leaves than in roots. When these halophytes were grown on a NaCl-free substrate, a trend toward K+ accumulation was observed and was better pronounced in leaves than in roots. Particularly high K+ concentrations were accumulated in Salicornia leaves. There were no principal differences in the partitioning of Na+ and K+ between organs of three halophyte species representing different ecological groups. At all substrate concentrations of NaCl, the total content of Na+ and K+ in leaves was higher than in roots. This distribution pattern persisted in Atriplex possessing salt glands, as well as in euhalophytes Salicornia and Climacoptera. The physiological significance of such universal pattern of ion accumulation and distribution among organs in halophytes is related to the necessity of water absorption by roots, its transport to shoots, and maintenance of sufficient cell water content in all organs under high soil salinity.

The influence of melt structure on trace element partitioning near the peridotite solidus

This experimental study examines the mineral/melt partitioning of Na, Ti, La, Sm, Ho, and Lu among high-Ca clinopyroxene, plagioclase, and silicate melts analogous to varying degrees of peridotite partial melting. Experiments performed at a pressure of 1.5 GPa and temperatures of 1,285 to 1,345 °C produced silicate melts saturated with high-Ca clinopyroxene, plagioclase and/or spinel, and, in one case, orthopyroxene and garnet. Partition coefficients measured in experiments in which clinopyroxene coexists with basaltic melt containing ~18 to 19 wt% Al2O3 and up to ~3 wt% Na2O are consistent with those determined experimentally in a majority of the previous studies, with values of ~0.05 for the light rare earths and of ~0.70 for the heavy rare earths. The magnitudes of clinopyroxene/melt partition coefficients for the rare earth elements correlate with pyroxene composition in these experiments, and relative compatibilities are consistent with the effects of lattice strain energy. Clinopyroxene/melt partition coefficients measured in experiments in which the melt contains ~20 wt% Al2O3 and ~4 to 8 wt% Na2O are unusually large (e.g., values for Lu of up to 1.33±0.05) and are not consistent with the dependence on pyroxene composition found in previous studies. The magnitudes of the partition coefficients measured in these experiments correlate with the degree of polymerization of the melt, rather than with crystal composition, indicating a significant melt structural influence on trace element partitioning. The ratio of non-bridging oxygens to tetrahedrally coordinated cations (NBO/T) in the melt provides a measure of this effect; melt structure has a significant influence on trace element compatibility only for values of NBO/T less than ~0.49. This result suggests that when ascending peridotite intersects the solidus at relatively low pressures (~1.5 GPa or less), the compatibility of trace elements in the residual solid varies significantly during the initial stages of partial melting in response to the changing liquid composition. It is unlikely that this effect is important at higher pressures due to the increased compatibility of SiO2, Na2O, and Al2O3 in the residual peridotite, and correspondingly larger values of NBO/T for small degree partial melts.

Anhydrous Partial Melting Experiments on MORB-like Eclogite: Phase Relations, Phase Compositions and Mineral-Melt Partitioning of Major Elements at 2-3 GPa

We present melt and mineral compositions from nominally anhydrous partial melting experiments at 2---3 GPa on a quartz eclogite composition (G2) similar to average oceanic crust. Near-solidus partial melts at 3 GPa, determined with melt traps of vitreous carbon spheres, have 55---57 wt % SiO2, rather less silica than the dacitic compositions that are generally assumed for near-solidus eclogite partial melts. At 2 GPa, equivalent near-solidus partial melts are less silicic ( 52 wt % SiO2). The 3 GPa near-solidus partial melts (up to melt fractions of 3%) are saturated in rutile and have 5 7---6 7 wt % TiO2. The G2 composition is K2O-poor (0 03 wt%), but a modified composition with 0 26 wt%K2O (G2K) produces dacitic near-solidus melts with 61---64 wt % SiO2. Rutile saturation for G2K extends to higher melt fraction ( 13%) and occurs at lower TiO2 melt contents (3 3 wt %) than for G2. These results can be understood in terms of a simplified thermodynamic model in which alkalis increase the SiO2 content of liquids saturated in quartz, which in turn diminishes the TiO2 concentrations required to maintain rutile saturation. Additionally, the mode of residual garnet and generation of silicic liquids by partial melting of anhydrous eclogite are linked, as garnet is required to mass-balance formation of appreciable SiO2-rich melt. Partitioning of Na between clinopyroxene and melt shows significant increases with pressure, but only modest shifts with changing temperature. In contrast, partitioning of Ti between cpx and melt, as well as between cpx and garnet, shows pronounced dependence on temperature for compositions relevant to anhydrous partial melting of eclogite. Mixtures between partial melts of eclogite and primitive picritic Hawaiian magmas are similar to magnesian, SiO2-rich compositions inferred from melt inclusions from the Koolau volcano. However, in detail, no eclogitic partial melt has been identified that is capable of explaining all of the compositional features of the exotic Koolau component. Based on phase compositions in our experiments, the calculated density of near-solidus eclogite is 3440 kg/m, notably less than commonly assumed. Therefore, the excess temperature required for a plume to support a given proportion of eclogite in the upper mantle may be less than previously assumed.

The partitioning of Na between melilite and liquid: part I. the role of crystal chemistry and liquid composition

The partitioning behavior of Na between melilite and liquid has been determined from the compositions of coexisting phases produced in slowly cooled (1°C/h) dynamic crystallization experiments on a single bulk composition corresponding to an average type B inclusion from the Allende C3V carbonaceous chondrite. Distribution coefficients ( D Na Mel/ L ) were determined over the entire range of melilite + spinel crystallization. For low Na concentrations (0.2–0.33 wt% Na 2O in the melts), sodium is incompatible in gehlenitic melilite (e.g., D Na Mel/ L = 0.4 at X Ak Mel = 0.22) but compatible in melilite more magnesian than X Ak Mel ∼ 0.50 (e.g., D Na Mel/ L = 1.5 at X Ak Mel = 0.65). Variations in D Na Mel/ L with composition for our experiments can be understood in terms of a simple thermodynamic model for the partitioning of Na between melilite and melt. The compositions of both melt and solid are important in determining the value of D Na Mel/ L and, with an empirical correction for Na 2O in the melt, D Na Mel/ L for experimentally determined partition coefficients in this study and in the literature can be predicted with an average deviation of 15% for melts containing up to 8 wt% Na 2O. The partitioning of Na between melilite and plagioclase in low-Na, Fe-free systems can also be predicted using a semiempirical model for the exchange equilibrium.

The partitioning of Na between melilite and liquid: part II. applications to Type B inclusions from carbonaceous chondrites

The zoning of Na in the melilite of Type B1 Ca-, Al-rich inclusions from carbonaceous chondrites reflects a combination of factors including the maximum temperature, T max , for melting, bulk composition, crystal dimensions and the degree of diffusive relaxation. We used experimentally determined partition coefficients for Na between melilite and liquid together with modes and compositions of phases in meteoritic inclusions to calculate Na zoning produced in melilite by crystallization from Na-bearing liquids. We then used a simple model for the diffusive relaxation of an originally igneous zoning profile to constrain the thermal history. For Allende Type B1 inclusion TS-34, the melilite compositions are consistent with an initial melting event (T max ∼ 1450°C) during which essentially Na-free melilite crystallized, followed by the introduction of Na during a hiatus, a second melting event with T max ∼ 1290°C in which Na-bearing melilite with X Ak Mel ≥ 0.47 grew on relict cores of melilite from the first melting event, and partial diffusive relaxation. For the Type B1 inclusion Vigarano 1623-8, previously published bulk and melilite compositions lead to the conclusion that T max did not exceed ∼1280°C during the last major melting event. A survey of literature data for other inclusions suggests that Na zoning in melilite may be a generally useful indicator of thermal history and that Type B1 inclusions were commonly subjected to multiple melting events with intervening periods of alteration. At any given value of X Ak Mel in TS-34, calculated melilite/liquid partition coefficients for Na are lower than values determined experimentally for melilite of similar composition because of liquid composition effects. The difference is more than a factor of two for X Ak Mel > 0.5, and it is likely, based on the activities of major oxides in the melt, that liquid composition effects are also important for other elements. On the other hand, modeling of diffusive relaxation for Na in melilite suggests that the diffusion coefficients are not strongly dependent on either X Ak Mel or Na concentration.

Water soluble calixarenes as possible metal ion extractants in polyethylene glycol-based aqueous biphasic systems

The behavior of a water soluble calixarene ligand has been investigated in an (NH4)2SO4/polyethylene glycol-2000 (PEG) aqueous biphasic system. Spectroscopic measurements indicate that 4-sulfonic-calix-6-arene partitions preferentially to the polymer-rich phase in this system. The utility of this ligand as a metal ion extractant was also investigated. The addition of the calixarene (10−2M in initial PEG-rich stock solution) did not significantly enhance the partitioning of Na+, Cs+, Sr2+, Ba2+, Co2+, Cd2+, or UO 2 2+ from the (NH4)2SO4-rich to the PEG-rich phase. The partitioning behavior of these metal ions is dependent, rather, on their Gibbs free energy of hydration (ΔGhyd*).

Inheritance of Potassium‐Sodium Nutritional Traits in Alfalfa

AbstractAlfalfa (Medicago sativa L.) growing on K‐depleted, semiarid, calcareous soil displays three K‐deficiency symptoms: (i) white spots on leaflets W, (ii) marginal chlorosis M, and (iii) normal leaflets on stunted plants (N). In a greenhouse study, we examined partitioning and heritability of K and Na nutritional traits in three alfalfa clones and their crosses, and also how K and Na soil fertility levels affected biomass production, genetic dependence of K and Na uptake and partitioning, and K use efficiency. Mother plants were propagated vegetatively and by seed from phenotype crosses in a low‐K, low‐Na, calcareous soil rooting medium. One trial used K‐ and Na‐amended soil. Harvests were at early bloom. Leaves contained more K than stems, with no difference among phenotypes; Na was uniform in stems, but leaves of M contained much more Na than leaves of N and W. With nonamended soil, K and Na uptake and partitioning among leaves, stems, and roots were significantly affected by cross. The Na:K ratio in leaves, stems, and roots was strongly influenced by phenotype and cross. Biomass production of leaves and stems differed among crosses and was increased by K fertilization; Na fertilization affected biomass only of leaves, and only in crosses M ✕ M and N ✕ N (Na may have partially replaced K). The shoot:root ratio was affected only by cross. Potassium use efficiency was affected by cross and by Na fertilization. Broad‐sense heritability for K and Na concentration was high, especially for Na in leaves and stems. Uptake and partitioning of Na and K in phenotype crosses supported narrow‐sense heritability as well. Genetics, rather than soil K‐Na competition, governed Na uptake, translocation, and utilization by phenotypes. Accordingly, characterization of K nutrition in alfalfa must consider Na levels. As phenotypes of alfalfa cultivars range widely in K‐Na nutritional traits, it should be possible to select for high yield and K use efficiency.

Sodium partitioning within the shoot of soybean

Uptake and partitioning of Na+ and Cl− in plants of soybean (Glycine max L. Merr. cv. Hodgson) exposed to moderate NaCl concentrations were studied over an 8‐day period. Plants showed marked retention of Na+ in the stems and low transport to laminae of young leaves. The xylem sap ascending the main axis was progressively depleted in Na+. The oldest leaf greatly contributed to Na+ depletion of the sap flowing to younger leaves. These results in combination with estimates of phloem recirculation indicated that Na+ accumulation in the young leaf was prevented both by depletion of Na+ from the xylem stream, and by a high recirculation of Na+ via the phloem. However, this protection of young leaves was effective only for very mild salinity treatment.