Search

Palms are becoming popular landscape plants in the upper desert region of the Southwest where water used for irrigation has elevated salinity. An experiment was conducted in a greenhouse to evaluate leaf damage and growth response of nine cold-resistant palm species to salinity. One-year-old potted seedlings were transplanted to 10-liter containers filled with loamy sand and irrigated with saline solutions containing 800, 2000, 5000, and 7500 mg/liter of predominantly NaCl salts. The corresponding electrical conductivity was 1.2, 4.4, 9.4, and 13.7 dS/m, respectively. Seedlings were irrigated at a leaching fraction of 30 to 35% for six months, and leaf growth, leaf injury, and leaf mineral contents measured. Under this irrigation regime, salinity of irrigation solutions approximately equals salinity of the soil saturation extract. Leaf growth and leaf injury were highly species-dependent. A significant growth reduction and leaf injury of Sabal palmetto, Butia capitata, and Trachycarpus fortunei appeared when irrigated with the 4.4 dS/m solution, those of Trithrinax brasiliensis, Brahea armata, and Sabal minor when grown with the 9.4 dS/m solution, and Washingtonia filifera, Washingtonia robusta and Phoenix canariensis, using the 13.7 dS/m solution. Injured leaves of poorly-tolerant species contained unusually large amounts of Na (10 to 70 g/kg) when irrigated with the 9.4 dS/m solution. W. filifera, W. robusta, and P. canariensis seem to be ideal species for saline areas. [ABSTRACT FROM AUTHOR]

Phytohormones play critical roles in regulating plant responses to stress. Here, we investigated the effects of salt stress and stress recovery by applying jasmonate to the two different rice ( Oryza sativa L.) cultivars Dongjinchalbyeo (DJC, salt-tolerant) and Dongjinbyeo (DJ, salt-sensitive). Salt stress remarkably decreased the root length of plants even at low NaCl concentration (20 m m). Salt stress led to a sharp increase in the concentrations of abscisic acid (ABA) in 20 and 40 m m NaCl, when compared with the control values. The concentrations of ABA in the salt-tolerant cultivar DJC plants progressively increased with increasing NaCl levels, whereas in the salt-sensitive cultivar DJ, they sharply decreased in all three parts of rice plants at 80 m m NaCl treatment. The decrease of jasmonic acid (JA) concentrations in salt-tolerant cultivar DJC was lesser than in the salt-sensitive cultivar DJ plants in the shoot. Post-application in the stressed plants with 30 μ m JA at 24 and 48 h after NaCl treatment, recovered salt inhibition on dry mass production more effectively than application of JA at 48 and 24 h before salt stress, and during salt stress simultaneously. The uptake of Na decreased especially in the salt-sensitive cultivar DJ plants, whereas there was an increase in Ca and Mg levels and slight increase of K by JA application. Leaf water potential, leaf photosynthetic rate, and maximum quantum yield of photosystem II (PSII) also remarkably recovered when 30 μ m JA was applied 24 h after the salt stress compared with the 40 m m NaCl-treated plants. These results clearly indicate that post-application with exogenous JA can ameliorate salt-stressed rice seedlings, especially the salt-sensitive cultivar rather than the salt-tolerant cultivar. This may change the balance of other endogenous plant hormones. [ABSTRACT FROM AUTHOR]

Twenty-five genotypes of early CIMMYT hexaploid wheat (Triticum aestivum L.) were screened for salt tolerance in a glasshouse experiment at 150 mol m-3 NaCl in sand culture. The genotypes Na(20)TPP, Penjamo 62, and Inia 66 exceeded all the lines in grain yield per plant under salt stress, whereas Nainari 60 and Norin 10 were the lowest of all genotypes. However, Jaral 66 and Yaqui 54 were the lowest of all the genotypes in all growth and yield attributes. Considerable variation in accumulation of Na+ and Cl- in different plant parts of 25 genotypes of early CIMMYT wheat under salt stress was observed. The genotype Noreste 66 was the lowest in leaf Na+ and Cl-, and it had highest leaf K/Na ratio and K versus Na selectivity of all the genotypes, but in terms of growth and grain yield, it was moderately tolerant. The other genotype Norin 10 was the highest in leaf Na+ and Cl- of all genotypes, but its leaf K/Na ratio and K versus Na selectivity were considerably low. However, in shoot biomass it was the highest and in grain yield the lowest of all genotypes. In view of phylogenetic lineage of the genotypes, most of the genotypes have evolved from Norin 10, so the trait of high uptake of Na+ and Cl- in most genotypes may have been inherited from Norin 10. The ion exclusion trait in the moderately salt tolerant genotype Noreste 66 was possibly inherited from Yaqui 50 as it was the only among all putative parents which showed low uptake of toxic ions. Overall, owing to the complex nature of the salt tolerance trait being controlled by polygenes, it was not easy to draw relationships between degree of salt tolerance and pattern of uptake of toxic ions and maintenance of leaf K/Na ratios. However, from the phylogenetic lineage of the 25 genotypes it was possible to draw relationships between degree of salt tolerance and mechanism of ion uptake between parents and progeny. [Copyright &y& Elsevier]

The effect of two simulated biological environments (protein-free and protein-containing) on ion uptake and physical properties of PVA/PVP hydrogels were explored in this work. It was found that over the immersion period in both media, wet mass of the hydrogels decreased and compressive moduli increased, likely due to increased polymer content with water loss as the hydrogels equilibrated with water. These changes were independent of polymer content and immersion medium. However, dry mass of the hydrogels increased dramatically when immersed in protein-free medium, changing only moderately in protein-containing medium. The increase in dry mass was attributed to ion uptake from immersion medium, as confirmed by EDXA. We postulate that differences between ion uptake in protein-free versus protein-containing medium is likely the result of serum proteins in the proteincontaining medium adsorbing to the surface, inhibiting transport of ions into the hydrogel. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effect of seaweed extract on macro and micro nutrient uptake of grapevine ( Vitis vinifera L. cv. Karaerik). One-year-old grapevine ( Vitis vinifera L. cv. Karaerik) saplings were planted in perlite with different nutrient element levels under greenhouse conditions. Three seaweed extracts, Maxicrop, Proton and Algipower, were sprayed on the foliage at different concentrations (0, 0.5, 1.0 and 2.0 g l -1 ). Results indicated that foliar application of seaweed extract increased Cu uptake of grapevine in the growth media which had insufficient nutrient elements. No significant differences in nutrient uptake of grapevine were obtained among the three seaweed extract types. The results showed that nutrient element level of growth media was more effective on stimulation of N, P, K, Ca, Fe, Mg, Mn and Zn uptake than seaweed extracts. In contrast, seaweed extract was more effective in supporting Cu uptake in vines than nutrient element level of growth media. [ABSTRACT FROM AUTHOR]

More than 85% of c-myc transcription is controlled by the nuclease hypersensitive element III1 upstream of the P1 promoter of this oncogene. The purine-rich sequence in the anti-sense strand forms a G-quadruplex, which has been recently implicated in colorectal cancer, and is proposed as a silencer element [Proc. Natl. Acad. Sci. USA 101 (2004) 6140]. This prompted us to characterize the thermodynamics and proton/counterion effect of the complementary pyrimidine-rich sequence, which forms a C-tetraplex. We report the thermodynamic parameters for folding of the pyrimidine-rich DNA fragment from this region into a C-tetraplex. At 20 °C, we observed a ΔG of -10.36 ± 0.13 kcal mol-1 with favorable enthalpy (ΔH=-75.99±0.99 kcal mol-1) and unfavorable entropy (TΔS=-65.63±0.88 kcal mol-1) at pH 5.3 in 20 mM NaCl for tetraplex folding. Similar characteristic stabilizing enthalpy and destabilizing entropy were observed at other pH and ionic strengths. Folding was induced by uptake of about two to three protons per mole of tetraplex while a marginal (0.5–1 mol/mol) counterion uptake was observed. In the context of current understanding of c-myc transcription we envisage a role of the i-motif in remodeling the G-quadruplex silencer. [Copyright &y& Elsevier]

Sodium–proton antiporters, also called Na+/H+ exchangers (NHE), are vital transmembrane proteins involved in multiple cellular functions including transepithelial ion transport and Na+ homeostasis of cells throughout the biological kingdom. Na+/H+ exchange is accelerated by cytosolic acidification and also by osmotically induced cell shrinking, thereby promoting recovery of the physiological pHi and volume. Eight isoforms of Na+/H+ exchangers have been cloned and characterized to date and share the same overall structure, but exhibit differences with respect to cellular localization, kinetic variables and plasma membrane targeting, in polarized epithelial cells. The electrogenic Na+ absorption across tight epithelia from invertebrates follow significantly different principles from the electroneutral Na+/H+ antiporter found in vertebrates. In all invertebrate cells examined, the antiporter displayed a 2Na+/1H+ transport stoichiometry and this transport was markedly inhibited by exogenous calcium and zinc. Na+/H+ exchangers (NHE) are present in crustacean hepatopancreatic cell type suspensions and are believed to function in acid-base regulation by driving the extrusion of protons across the hepatopancreatic epithelium in exchange for Na+ in the sea water. A brief review of current knowledge about Na+/H+ exchangers has been presented. In addition, understanding of hepatopancreatic Na+/H+ exchange is described as obtained after isolation of purified E-, R-, F- and B-cell suspensions from the whole organ by centrifugal elutriation. [Copyright &y& Elsevier]

To understand the mechanisms of salt tolerance in a halophyte, sea aster (Aster tripolium L.), we studied the changes of water relation and the factors of photosynthetic limitation under water stress and 300 mM NaCl stress. The contents of Na+ and Cl- were highest in NaCl-stressed leaves. Leaf osmotic potentials (Ψs) were decreased by both stress treatments, whereas leaf turgor pressure (Ψt) was maintained under NaCl stress. Decrease in Ψs without any loss of ψt accounted for osmotic adjustment using Na+ and Cl- accumulated under NaCl stress. Stress treatments affected photosynthesis, and stomatal limitation was higher under water stress than under NaCl stress. Additionally, maximum CO2 fixation rate and O2 evolution rate decreased only under water stress, indicating irreversible damage to photosynthetic systems, mainly by dehydration. Water stress severely affected the water relation and photosynthetic capacity. On the other hand, turgid leaves under NaCl stress have dehydration tolerance due to maintenance of Ψt and photosynthetic activity. These results show that sea aster might not suffer from tissue dehydration in highly salinized environments. We conclude that the adaptation of sea aster to salinity may be accomplished by osmotic adjustment using accumulated Na+ and Cl-, and that this plant has typical halophyte characteristics, but not drought tolerance. [ABSTRACT FROM AUTHOR]

Compensation by dark‐period uptake of NH4+ and NO3– in the grasses Phleum pratense L. and Festuca pratensis Huds. following N deprivation during the preceding light period was investigated in flowing solution culture under an artificial 10/14 h light/dark cycle. N was supplied as either NO3–, NH4+ or NH4NO3 at 20±5 mmol m–3, available continuously or only during the dark period, for 5–10 d. Intermittent N supply did not affect total daily N uptake, growth rate or net partitioning of dry matter. Net uptake and influx of NO3– varied similarly throughout the diurnal cycle when NO3– was supplied continuously, with a marginal contribution by NO3– efflux. Influx was significantly higher and efflux slightly higher following interruption of NO3– supply during the light period. Nitrate accounted for 80% of N in xylem exudate except between hours 6–9 of the light period when the amino acid concentration increased 3‐fold, primarily as glutamine. Diurnal variation in relative NO3– uptake exhibited five phases of constant acceleration/deceleration, described reasonably well assuming NO3– influx was subject to metabolic co‐regulation by NO3– and amino acid levels in the cytoplasmic compartment of the roots. Accordingly, influx is determined by variation in root NO3– levels throughout the dark period and the first half of the light period, but is down‐regulated by increased amino acid levels during the second half of the light period. The sharp light/dark transitions affect transpiration rate and hence xylem N flux which, in turn, affect NO3– levels in the cytoplasmic compartment of the roots and the rate of NO3– assimilation in the shoot. [ABSTRACT FROM PUBLISHER]

Despite extensive research, the mechanism by which glass ionomer cements take up fluoride ions from solution remains unclear. To date, the majority of studies have concentrated on measuring the removal of ions from solution. In this study, we demonstrate the application of X-ray photoemission spectroscopy and secondary ion mass spectrometry to the surface analysis of the cements, after the introduction of fluoride either by doping or by immersion. Fluoride ion uptake from potassium fluoride solution is correlated with the formation of a surface layer which is rich in calcium as well as fluoride. [Copyright &y& Elsevier]

The transport of aqueous salts containing mono-, di- and trivalent metal and tetravalent metal complex ions across ultrathin polyvinylammonium/polyvinylsulphate (PVA/PVS) membranes is described. The membranes were prepared by electrostatic layer-by-layer (LBL) assembly of the two polyelectrolytes. Using spectroscopic measurements and permeability studies, it is demonstrated that the transport of copper(II) chloride, lanthanum(III) chloride, barium chloride and potassium hexacyanoferrate(II) is accompanied by the permanent incorporation of the metal and metal complex ions in the membrane. Upon the uptake of copper, lanthanum and hexacyanoferrate ions, the membranes become cross-linked so that the permeation rates of other salts not taken up by the membrane, e.g. sodium chloride, potassium chloride and magnesium chloride, are decreased. The uptake of barium ions leads to a decrease of the cross-linking density of the membrane so that the permeation rate of NaCl is increased. Possible mechanisms for the ion uptake are discussed. [Copyright &y& Elsevier]

Plants subjected to stress show accumulation of proline and other amino acids. The role played by accumulated amino acids in plants varies from acting as osmolyte, regulation of ion transport, modulating stomatal opening, and detoxification of heavy metals. Amino acids also affect synthesis and activity of some enzymes, gene expression, and redox-homeostasis. These roles played by amino acids have been critically examined and reviewed. [ABSTRACT FROM AUTHOR]

The physiological effects of humic substances (HS) on some aspects of plant growth and metabolism are examined. Evidence has been presented on that the effect of HS on plant growth depends on the source, concentration and molecular weight humic fraction. While a low molecular size (LMS<3500 Da) fraction easily reaches the plasmalemma of higher plant cells and, in part, is taken up into them, a high molecular size fraction (HMS>3500 Da) is not absorbed and can interact only with the cell wall. Therefore, a LMS fraction is the major candidate for determining the positive effects of HS on plant growth. The latter effects are in part exerted at the level of the plasma membrane by positively influencing the uptake of some nutrients, and in particular that of nitrate. The effects on the intermediary metabolism are less understood, albeit it seems that HS may influence both respiration and photosynthesis. Humic matter appears also to display an hormone-like activity. It is not clear if this activity is strictly linked to the chemical structure of HS or whether it depends on hormones of microbial origin entrapped into them. In any case, HS exhibit stimulatory effects on plant cell growth and development. [Copyright &y& Elsevier]

Soil salinity is a major limitation to legume production in many areas of the world. The salinity sensitivity of soybean was studied to determine the effect of salinity on seed germination, shoot and root dry weights, and leaf mineral contents. Three soybean cultivars, Lee, Coquitt, and Clark 63, were planted in soils of different salinity levels. The electrical conductivity (EC) of the soils used in this experiment was 0.5 dS m-1 . The soil salinity treatments were 0.5, 2.5 4.5, 6.5 and 8.5 dS m-1 . Saline drainage water from a drainage canal with an EC of 15 dS m-1 was used to treat the soil samples in order to obtain the desired salinity levels. Germination percentages were recorded 10 days after planting. Shoot and root dry weights of 45-day-old plants were measured. Nutrient concentrations for Na+ , K+ , Ca2+ , Mg2+ and Cl- were determined. Germination percentages were significantly reduced with increasing salinity levels. The cultivar Lee was less affected by salinity stress than Coquitt and Clark 63. At 8.5 dS m-1 a significant reduction in plant height was found in all three cultivars. However, Lee plants were taller than plants of the other two cultivars. Salinity stress induced a significant increase in leaf sodium (Na+ ) and chloride (Cl- ) in all cultivars. However, the cultivar Lee maintained lower Na+ and Cl+ concentrations, a higher potassium (K+ ) concentration and a higher K+ /Na+ ratio at higher salinity levels than Coquitt and Clark 63. Saline stress reduced the accumulation of K+ , calcium (Ca2+ ) and magnesium (Mg2+ ) in the leaves of the cultivars studied. This study suggests that Lee is the most tolerant cultivar, and that there is a relationship between the salt tolerance of the cultivar and macronutrient accumulation in the leaves. [ABSTRACT FROM AUTHOR]

Gametophytes of Onoclea sensiblis L. were grown under various light and media‐ion conditions to gain a better understanding of the source/sink relationships between photosynthetic and ion‐absorbing cells. There was a clear interdependency between green cell and rhizoid functions, such that the growth and development of the rhizoids was completely dependent on the internal delivery of photosynthates from green cells, and conversion of the one‐dimensional filament into the two‐dimensional prothallus required monovalent cations that could only be provided by rhizoid uptake. The need for monovalent cations was related to osmotic demands of dividing and expanding cells; prothallial development was blocked by monovalent cation deficiency, and the system resorted to Na+ uptake to support cell expansion when K+ was absent. Surgical excisions of filament cells further demonstrated the high degree of coordinated growth between the light‐absorbing and ion‐absorbing regions. It was also learned that excised sub‐apical cells of the protonemata, like the intensively studied apical cell, were capable of remodelling remnants of the filament into a normal prothallus. [ABSTRACT FROM PUBLISHER]

The uptake and distribution of eight metallic elements were examined in wheat seedlings for a period of 12 d with a radioactive multitracer technique. The radioactive nuclides of the seedlings were simultaneously determined by γ-ray spectrometry. All of the elements studied were taken up by the wheat seedlings and mainly accumulated in the roots. Only some elements were transported to shoots and leaves of the seedlings or bound to leaf proteins, and two elements were transported into the chloroplast. Uptake of most elements reached a maximum on the fifth or the eighth day and then gradually decreased afterward. In the cases of 95mTc and 72Se, the uptake increased continuously within 12 d without the peak uptake. The change of elemental concentrations was dependent on uptake and excretion rates. The dynamics of metal elements taken up by the wheat seedlings and their distribution in roots, shoots, and leaves were different for each element, suggesting that it may depend on the characteristics of the elements. [ABSTRACT FROM AUTHOR]

Interaction of elements in the course of element uptake by carrot ( Daucas carota cv. U.S. harumakigosun) exerted by the addition of elements, such as Rb, Zn, and Al, was investigated. For the purpose of precise evaluation of uptake behavior, the simultaneous determination of absorption of Na, Be, Sr, Mn, Co, Zn, Ce, Pm, and Gd was conducted by the multitracer technique. For root uptakes, Al exhibited its influence on the uptake of essential elements and on the uptake of toxic or unbeneficial ones, presumably as a result of the large electric valency that caused cell membrane disintegrity. On the other hand, Zn as a divalent cation only affected the uptake of essential and beneficial elements. Rubidium, which is a monovalent cation, did not exhibit any effect on the uptake of other ions. Concerning shoot uptakes, inhibition by Zn and Al, but not by Rb, was observed for the uptake of Sr, Mn, Co, and Zn. From the preent investigation, it is suggested that there exists an interaction between added ions and the elements taken into plants and that the degree of interaction increases in the increasing order of ionic valency: M+ (Rb), M2+ (Zn), and M3+ (Al). [ABSTRACT FROM AUTHOR]

Acid–base properties of cell walls isolated from various root tissues of 7-day-old lupine seedlings and 14-day-old lupine plants grown in various media were studied. The ion-exchange capacity of root cell walls was estimated at various pH values (from 2 to 12) and constant ionic strength (10 mM). The parameters determining the qualitative and quantitative composition of cell wall ionogenic groups along the root length and in its radial direction were estimated using Gregor's model. This model fits the experimental data reasonably well. Four types of ionogenic groups were found in the cell walls: an amino group (p Ka ∼ 3), two types of carboxylic groups (p Ka ∼ 5 and 7.3, the first being the carboxylic group of galacturonic acid), and a phenolic group (p Ka ∼ 10). The number of functional groups of each type was estimated, and the corresponding ionization constant values were calculated. It is shown that the chemical composition of the ionogenic groups was constant along the root length as well as in its radial direction and did not depend on either physiological state or root nutrition, while the number of different groups varied. The content of carboxylic groups of α-D-polygalacturonic acid in the root cell walls of 14-day-old plants was shown to depend on the distance from the root tip, being maximal in the zone of lateral roots. The number of these groups was 10- and 2-fold less in the central cylinder compared to that of cortex for 14-day-old plants and 7-day-old seedlings, respectively. [ABSTRACT FROM AUTHOR]

The entry of calcium and magnesium from external sources into mycorrhizal roots of 3-year-old Norway spruce trees (Piceaabies [L.] Karst.) was monitored. Roots of intact plants were exposed for various periods of time, ranging from 2 min to 48 h, to nutrient solutions which contained the stable-isotope tracers 25Mg and 44Ca. After labelling, samples of roots were excised from the plants, shock-frozen, cryosubstituted and embedded. The resulting isotope composition in this material was analysed by a laser-microprobe-mass-analyser (LAMMA) at relevant positions within cross-sections of the roots. For both elements, we determined (i) the fractions of the isotopes originating from the plant prior to labelling, and (ii) the fraction of isotopes originating from the corresponding tracer that penetrated into the root. Both divalent cations rapidly penetrated across the cortical apoplast and reached the endodermis. After 2 min of exposure to the labelling solution, an initial transient gradient of the tracers could be observed within the root cortex. Subsequently, calcium as well as magnesium equilibrated between the apoplast of the entire cortex and the external tracer with a half-time, t1/2, of about 3 min. In contrast, the kinetics of radial movement into the vascular stele showed a delay with a t1/2 of 100–120 min. We take this as strong evidence that there exists a free apoplastic path for divalent cations in the cortex and that the endodermis is a major barrier to the further passage of Mg and Ca into the xylem. While 25Mg in the labelling solution exchanged rapidly with Mg in the cortical apoplast, the exchange across the plasma membrane with Mg present in the protoplasm of the same cortical cells was almost 2 orders of magnitude slower. The kinetics of Ca and Mg entry at +6 °C were similar to those obtained at a root temperature of +22 °C. [ABSTRACT FROM AUTHOR]

Grafting is a widely used practice for asexual propagation of fruit trees. Many physiological, biochemical, and molecular changes occur upon grafting that can influence important horticultural traits. This technology has many advantages, including avoidance of juvenility, modifying the scion architecture, improving productivity, adapting scion cultivars to unfavourable environmental conditions, and developing traits in resistance to insect pests, bacterial and fungal diseases. A limitation of grafting is scion-rootstock incompatibility. It may be caused by many factors, including insufficient genetic proximity, physiological or biochemical factors, lignification at the graft union, poor graft architecture, insufficient cell recognition between union tissues, and metabolic differences in the scion and the rootstock. Plant hormones, like auxin, ethylene (ET), cytokinin (CK), gibberellin (GA), abscisic acid (ABA), and jasmonic acid (JA) orchestrate several crucial physiological and biochemical processes happening at the site of the graft union. Additionally, epigenetic changes at the union affect chromatin architecture by DNA methylation, histone modification, and the action of small RNA molecules. The mechanism triggering these effects likely is affected by hormonal crosstalk, protein and small molecules movement, nutrients uptake, and transport in the grafted trees. This review provides an overview of the basis of physiological, biochemical, and molecular aspects of fruit tree grafting between scion and rootstock., (© The Author(s) 2022. Published by Oxford University Press. All rights reserved.)

The rate of nitrogen uptake by seven Sphagnum species, which from a gradient from hummock to hollow and from ombrotrophic to minerotrophic conditions, was measured as the decrease in the concentrations of NH4+ and NO3- from solutions in which capitula were grown under laboratory conditions. The highest uptake rate was by individuals of each species with large capitula and a high number of ion exchange Sites, i.e. lawn species (S. pulchrum, S. fallax, S. papillosum and S. magellanicum). On a dry-mass basis, the most effective species were the hummock species (S. fuscum and S. rubellum), even though these species have a low dry mass. Hummock species, which occur in high densities and have high potential N-uptake rates on a dry-mass basis, were the most effective species in retaining available nitrogen. [ABSTRACT FROM AUTHOR]

Nonanoic acid, which inhibits germination in several seeds, enhanced ion efflux from embryonic axes of Cicer arietinum L., especially at temperatures above 25°C. Other short chain fatty acids had little effect on germination and ion leakage. Nonanoic acid also decreased uptake of 86Rb+ and 22Na+ and increased efflux of both isotopes from the embryonic axes into the incubation solution. Fusicoccin, which stimulates early germination in C. arietinum, counteracted the effects of nonanoic acid at both 25 and 30°C. These results suggest that nonanoic acid affects the integrity of plasmalemma and other membrane systems. Nonanoic acid thus inhibits cell elongation during early germination by disturbing ion exchange and inhibiting water uptake. [ABSTRACT FROM AUTHOR]

Four-week-old sunflower plants (Helianthus annuus L. cv. Halcón), grown in different nutrient solutions, were used to study the effects of gibberellic acid (GA3) on K+ (Rb+) uptake by roots or transport to the shoot. Gibberellic acid application to the nutrient solution did not affect the exudation process of excised roots. When GA3 was sprayed on leaves 2 to 6 days before excising the roots, the rate of exudation and the K+ flux increased. When the exudation study was done keeping the roots in a nutrient solution in which Rb+ replaced K+, the GA3effects were evident also on Rb+ uptake and transport. In intact plants, GA3 increased the Rb+ transported to the shoot but did not affect Rb+ accumulation in the root. It is suggested that these GA3 effects can be explained, if it is assumed that GA3 acts on the transport of ions to the xylem vessels. [ABSTRACT FROM AUTHOR]

The effects of boron‐deficient culture were studied on the unicellular diatom. Cylindrotheca fusiformis Reimann and Lewin. After 24 to 30 h, cell division was almost completely inhibited in boron‐deficient cultures. By 48 h of culture, boron‐deficient diatoms had approximately twice the modal cell volume of control cells, and at least twice the amount of organic constituents such as protein (2.0x), insoluble carbohydrate (2.4x), total phenols (2.6x), and chlorophyll at (2.1x). Boron deficiency led to irreversible damage after this time. Dark respiration was 1 nmol O2/min × 106 cells for both control and boron‐deficient diatoms prior to 40 h of culture. By 48 h, the respiratory rate of boron‐deficient diatoms was double that of controls. The proportion of 14C‐glucose metabolized by the pentose phosphate pathway was similar in both control and boron‐deficient diatoms after 24 and 48 h of culture. After 24 h, the in vitro activity of glucose‐6‐phosphate dehydrogenase was similar in both control and boron‐deficient cells, although the pool size of its substrate, glucose‐6‐phosphate, was 26% greater in boron‐deficient cells. The cellular amount of glucose‐6‐phosphate dehydrogenase continued to increase once mitosis was arrested in boron‐deficient diatoms. Boric acid (1 mM) inhibited 6‐phosphogluconate dehydrogenase by 18% in diatom homogenates. During the early stages of boron deficiency, the uptake of silicate, nitrate, and phosphate, and the in vitro activity of β‐glucosidase were similar to control diatoms. After cell division was inhibited, boron‐deficient diatoms accumulated more nitrate and phosphate, and retained a higher level of β‐glucosidase than control cells. [ABSTRACT FROM AUTHOR]

The separate and combined effects of Na+ and K+ on ATPase activity of microsomal fractions from the roots of the halophytic Plantago maritima and the less salt-tolerant Plantago coronopus were investigated in the presence of Mg+ATP or Ca+ATP (at equimolar ratios) as substrate. The ATPase activity in the presence of Mg+ATP was stimulated by Na+ and by K+ when they were added separately, but their combination reduced the enzyme activity. In the presence of Ca+ATP, however, the enzyme activity was stimulated by the combined addition of Na+ + K+ as well, and their action was qualitatively additive, hut experimentally lower. The two complexes as substrate probably served as allosteric effectors and induced different types of enzyme responses to monovalent cations. The Na+-stimulation and K+-stimulation of the ATPase activity could be separated by growing the plants under saline conditions. The Na+-stimulation of the ATPase was lowered while the K+-stimulation remained unchanged. The corresponding Na+ influx of the roots could also be blocked without influencing K+ influx of the roots. This kind of separation of ion fluxes and ATPases presumes a transport system model which possesses several units and which is accessible for regulation by hormones, lipids and divalent cations.

The anion-exchange capacities (AEC) of roots of intact plants of two plum clones [Marianna 2624 (Prunus cerasifera × P. munsoniana) and Myrobalan 3-J (P. cerasifera)] were assessed with an anionic dye, eosin Y. The positively charged eosin-specific adsorption sites were metabolically dependent and also affected by nutrient status. Myrobalan 3-J roots adsorbed twice as much exchangeable NO3- as did Marianna 2624. Since we previously showed that net nitrate uptake by Myrobalan 3-J persisted at half the ambient nitrate concentration as that characteristic of Marianna 2624, the data provide circumstantial support for a functional role of labile anion binding in active uptake at dilute concentrations of ambient nitrate. [ABSTRACT FROM AUTHOR]

Genetic relationships between salt tolerance and expression of various physiological traits during vegetative growth in tomato, Lycopersicon esculentum Mill., were investigated. Parental, F1, F2 and backcross progeny of a cross between a salt tolerant (PI174263) and a salt sensitive tomato cultivar ('UCT5') were evaluated in saline solutions with electrical conductivity of 0.5 (non-stress) and 20 dS/m (salt stress). Absolute growth, relative growth, tissue ion content, leaf solute potential and the rate of ethylene evolution were measured. Growth of both parents was reduced under salt stress; however, the reduction was significantly less in PI174263 than 'UCT5', suggesting greater salt tolerance of the former. Under salt stress, leaves of PI174263 accumulated significantly less Na+ and Cl- and more Ca2+ than leaves of 'UCT5'. Across parental and progeny generations, growth under salt stress was positively correlated with leaf Ca2+ content and negatively correlated with leaf Na2+ content. In contrast, no correlation was observed between growth and either leaf solute potential or the rate of ethylene evolution under salt stress. Generation means analysis indicated that under salt stress both absolute and relative growth and the Na+ and Ca2+ accumulations in the leaf were genetically controlled with additivity being the major genetic component. The results indicated that the inherent genetic capabilities of PI174263 to maintain high tissue Ca2+ levels and to exclude Na+ from the shoot were essential features underlying its adaptation to salt stress and that these features were highly heritable. Thus. tissue ion concentration may be a useful selection criterion when breeding for improved salt tolerance of tomato using progeny derived from PI174263. [ABSTRACT FROM AUTHOR]

Aluminium is the most important growth-limiting factor in many acid soils throughout the world. Physiological effects of Al toxicity and mechanisms of tolerance are not well understood. An initial uptake of Al is confined to the apoplasm. Aluminium complexes (whose exact identification is beyond current experimental techniques) enter the cytosol slowly and only after prolonged exposure. Electrochemical properties of the cell wall Donnan free space as well as the plasma membrane of root cells are altered by the presence of Al ions that are polyvalent cations in acidic environments. The primary Al effects are very fast (taking only seconds to several minutes to develop) and may therefore occur while Al is still in the Donnan free space and on the apoplasmic side of the plasma membrane. Resumption of root growth upon removal of Al ions supports such a claim. Aluminium affects membrane permeability for both electrolytes and non-electrolytes; it reduces accumulation of divalent cations (especially Ca and Mg) by interfering with the membrane transport. Aluminium alters the pattern of Ca2+ fluxes across the plasma membrane, thus supposedly disturbing symplasmic Ca2+ homeostasis. Supplemental Ca2+ can greatly alleviate deleterious Al effects. Frequently observed changes in the secretory activity of root cells exposed to Al are mediated through altered cell Ca2+ homeostasis; they result in cessation of cell wall growth and stoppage of root elongation. Involvement of calmodulin in the Al-related phenomena is suggested to be indirect, at least in the initial stages of the Al treatment when Al is likely to be confined to the apoplasm. The role of growth substances, at least auxins and cytokinins, in the Al toxicity syndrome appears to be related to the Ca-Al interactions that may alter the pattern of auxin transport as well as cytokinin biosynthesis and transport. [ABSTRACT FROM AUTHOR]

Growth responses, leaf water and osmotic relations, and tissue ionic and organic solute contents of Sporobolus virginicus (I,.) Kunth, grown under solution culture in salinities of up to 450 mM NaCI, were studied. Shoot growth was stimulated by intermediate salt levels, concurrent with both an accumulation of Na+ and C1- in shoots and a slight increase in shoot succulence. Root growth was stimulated at salinities of up to 450 mM NaCl. Osmotic adjustment of shoots was predominantly due to Nc+, Cl-, and soluble carbohydrate accumulation, though a slight reduction in shoot succulence may have played a minor role at high salinity. Shoot Na+ and Cl- accumulation was tightly controlled, not exceeding levels required for osmotic adjustment, due in part ion secretion by leaf salt glands. Shoots were selective for K+ over Na+, maintaining fairly constant K- concentrations with increasing salinity, resulting in relatively high K-/Na+ ratios at high salinity. Increasing NaCI stimulated the accumulation of K- in roots, which may have acted as a reservoir of K- for shoots at high salinity. Glycinebetaine, and to a lesser extent praline and trigonelline. accumulated in shoot tissues with increasing salinity, though trigonelline concentrations were insufficient to be osmotically significant. Accumulation was closely associated with increases in shoot sap osmolality. It is proposed that glycinebetaine may act as a compatible solute in S. virginicus, as levels were sufficiently high to effect total osmotic adjustment of the cytoplasm at high salinity. [ABSTRACT FROM AUTHOR]

Commonality in diurnal variation in net uptake of NH4+, NO3- and K+ by the grasses Phleum pratense L. cv. Bodin (timothy), and Festuca pratensis Huds. cv. Salten (fescue) was evaluated in flowing solution culture under a semi-natural light regime. Hourly uptake rates from constant 20 mmol m-3 concentrations of each ion were measured concurrently over 7 d, without physical disturbance. The light period was 11 h, natural light supplemented by constant artificial illumination, with a step-transition to a 13 h dark period. Uptake of all three ions showed a broadly similar pattern of diurnal variation, rates increasing during the light period and decreasing during the darkness to a minimum within ±2 h of the end of the dark period. The amplitude was greatest during high-irradiance days, and both proportionately and absolutely greater for NH4+ (mean min:max uptake=0.24) than NO3- (min:max=0.41) or K+ (min:max=0.34). There were significant differences between NH4+ and the other two ions (NO3- and K+) whose behaviour coincided in almost all respects, in timing of maximum and minimum rates, and acceleration in uptake during the light period. Preferential uptake of NH4+ over NO3- increased sharply during the first half of the light period; in relative terms NH4+ uptake accelerated twice as fast as NO3- uptake. Fescue always absorbed more NH4+ than NO3-, but timothy showed a preference for NO3- during part of the dark period. The results are interpreted in terms of the hypothesis that diurnally fluctuating 'sink-strength' for nutrients is the primary determinant of nutrient transport rates, although uptake may become temporarily uncoupled from nutrient demand during periods of physiological stress or perturbation, such as towards the end of the dark period, during which uptake rates are determined by factors (e.g. carbohydrate supply) other than current nutrient demand. [ABSTRACT FROM PUBLISHER]

The immediate and posteffects of various concentrations of NaNO2 on ion uptake of wheat (Triticum aestivum L. cv. GK Öthalom) seedlings were studied at different pH values. Without pretreatment, the higher the concentration of NaNO2 the greater was the decrease in uptake of K+ into the roots, both at pH 4 and pH 6. At pH 6 but not at pH 4 the reverse was true when the seedlings were pretreated with NaNO2. Due to the high Na+ content of the roots, an effect of Na+ in this process cannot be excluded. Nitrite was taken up by the roots more rapidly than nitrate. Nitrite at 0.1 mM in the medium induced the development of an uptake system for both NO−2 and NO−3 in wheat roots. At higher concentrations pretreatment with NO−2 decreased NO−3 uptake by the roots, but NO3 did not inhibit the uptake of NO2. The toxic effect of NO−2 was strongly pH dependent. Lower pH of the external solution led to an increased inhibition by NO−2 of both ion uptake and growth of seedlings. The inhibitory effect of NO−2 differed considerably for roots and shoots. The roots and especially the root hairs were particularly sensitive to NO−2 treatment. [ABSTRACT FROM AUTHOR]

Maintenance of ion gradients across plant membranes is considered to be an important process requiring respiratory energy in plant tissues. In order to test this hypothesis, roots of intact plants of potato (Solanum tuberosum L. cv. Alcmaria and cv. Pimpernel) were incubated in a closed circulation system. Electrical conductivity of the solution surrounding these roots was continuously monitored to determine total ion efflux into demineralized water. Anion efflux rate from the symplast was 35 neq (g dry weight)−1 s−1. In combination with literature data on the specific costs of ion transport, this efflux rate yields the respiration rate associated with re‐uptake balancing efflux (i. e. maintenance of cellular ion concentrations). The results suggest that energy costs associated with re‐uptake of ions may account for up to 25–50% of the total respiratory costs involved in ion influx. [ABSTRACT FROM AUTHOR]

Net rates of NO3- and K+ uptake were compared for oilseed rape (Brassica napus L. cv. Jet neuf), perennial ryegrass (Lolium perenne L. cv. S23), Italian ryegrass (Lolium multiflorum Lam. cv. Augusta) and wheat (Triticum aessivum L. cv. Fenman) in flowing solution culture during a 4-day sequence of low-low-high-high natural irradiance. Concentrations of NO3- (10 μM) and K+ (2.5 μM4 mmol NO3 m-2 h-1 and >1.4 mmol K+ m-2h-2. These higher rates were maintained throughout the following night. The lag-time between maximum irradiance and the onset of the highest acceleration in uptake was greater for NO3 (5-8 h) than for K+ (≤ 1h) in rape, wheat and Italian ryegrass. Uptake of NO3 by perennial ryegrass showed an almost constant acceleration for 18 h following maximum irradiance. In all species the measured maximum inflows (uptake rate per unit root length) of both ions were greater than theoretical maximum potential inflows to a non-competing infinite-sink root in soil, by factors of 7 and 36, respectively, for NO3- and K+, averaged over all species.

The respiratory characteristics of the roots of Carex diandra Schrank and Carex acutiformis Ehrh. were investigated. The aims were, firstly to determine the respiratory energy costs for the maintenance of root biomass, for root growth and for ion uptake, and secondly to explain the higher rate of root respiration and ATP production in C. diandra. The three respiratory energy components were derived from a multiple regression analysis, using the relative growth rate and the net rate of nitrate uptake as independent variables and the rate of ATP production as a dependent variable. Although the rate of root respiration and ATP production was significantly higher in C. diandra than in C. acutiformis, the two species showed no significant difference in their rate of ATP production for the maintenance of biomass, in the respiratory energy coefficient for growth (the amount of ATP production per unit of biomass produced) and the respiratory energy coefficient for ion uptake (amount of ATP production per unit of ions absorbed). It is concluded that the higher rate of root respiration of C. diandra is caused by a higher rate of nitrate uptake. At relatively high rates of growth and nitrate uptake, the contribution of the rate of ATP production for ion uptake to the total rate of ATP production amounted to 38 and 25% for C. diandra and C. acutiformis, respectively. At this growth rate, the respiratory energy production for growth contributed 37 and 50%, respectively, to the total rate of ATP production. The relative contribution of the rate of ATP production for the maintenance of biomass increased from 25 to 70% with increasing plant age for both species. The results suggest that ion uptake is one of the major sinks for respiratory energy in roots. These experimentally derived values for the rate of ATP production for the maintenance of biomass, the respiratory energy coefficient for growth and the respiratory energy coefficient for ion uptake are discussed in relation to other experimentally and theoretically derived values. [ABSTRACT FROM AUTHOR]

The influence of the phytoeffective mycotoxin, tentoxin, [cyclo-(L-leucyl-N-methyl-trans-dehydrophenyl-alanyl-glycyl-N-methyl-L-alanyl)] on K+ uptake and on trans-location of K+ from roots to shoot was studied in 14-day-old winter wheat plants (Triticum aestivum L. cv. Martonvásári-8) grown at different levels of K+ supply. For comparison, the effects of 2,4-dinitrophenol and valinomycin were also investigated. In 1-h experiments 1 pM tentoxin reduced K+ influx in the roots over the external K+ concentration range 0.1 to 1 mM (low-K+ plants), whereas stimulation was observed at lower and higher K+ concentrations. On the other hand, in plants grown at 0.3 mM K+, tentoxin stimulated the translocation of K+ from roots to shoots in 5-h experiments. Valinomycin affected K+ transport only at high K+-status (slight stimulation). In low-K+ plants 2,4-dinitrophenol (DNP) caused drastic inhibition of K+ uptake, but in high-K+ plants uptake was only slightly inhibited and translocation slightly stimulated. It is concluded that the opposite effects of tentoxin on K+ uptake and translocation agree with the directions of the H+-ATPases pumping H+ towards the apoplast and located at the cortex plasmalemma and the xylem parenchyma plasmamembrane, respectively. These effects should probably be attributed to the interaction between tentoxin and the K+-carrier protein rather than to a direct influence of tentoxin on H+-ATPase. [ABSTRACT FROM AUTHOR]

The roots of many angiosperm species possess tow Casparian bands, one in the endodermis and one in the outermost layer of the cortex. Over most of the root surface in these species, ions are taken up by the epidermis and may be transported symplastically to the xylem. [ABSTRACT FROM AUTHOR]

The article focuses on the recent progress in understanding the regulation of appearance of NR and NIR by nitrogen-containing ions and light, by the developmental and physiological state of the plastids as well as by the endogenous competence of the plant for NR and NIR induction. Moreover, the progress of immuno-chemical techniques for detection and quantitation of NR and NIR levels as well as the use of cDNA clones in investigating changes of the transcript level are summarized with regard to the question of how changes of NR and NIR levels are caused by the above mentioned factors.

The previous demonstration that the large late metaxylem vessels of field‐grown maize (Zea mays L. cv. Rosella) roots do not lose their crosswalls until they are 20–30 cm from the tip, and that the presence of a soil sheath outside the root was indicative of immature vessels within, greatly strengthened the hypothesis that ion accumulation into these roots was by uptake into living xylem element vacuoles. Proposals that salt movement into the xylem was by leakage or secretion into dead vessels became much less plausible. Potassium concentration in the vacuoles of late metaxylem elements was measured by X‐ray microanalysis in unetched fracture faces of bulk, frozen‐hydrated pieces of sheathed roots, and found to be in the range 150–400 mM. Potassium concentration in open vessels of bare roots, measured both with the microprobe and by spectrophotometry of aspirated sap, was in the range of 5 to 25 mM. It is concluded that uptake of potassium (and possibly other ions) is into living xylem elements, and that its release to the transpiration stream occurs by the breakdown of their crosswalls and the addition of their vacuoles to the solution in the vessels above. [ABSTRACT FROM AUTHOR]

Herbaceous plants grown with free access to nutrients exhibit inherent differences in maximum relative growth rate (RGR) and rate of nutrient uptake. Measured rates of root respiration are higher in fast-growing species than in slow-growing ones. Fast-growing herbaceous species, however, exhibit lower rates of respiration than would be expected from their high rates of growth and nitrate uptake. We investigated why the difference in root O2 uptake between fast- and slow-growing species is relatively small. Inhibition of respiration by the build-up of CO2 in closed cuvettes, diurnal variation in respiration rates or an increasing ratio of respiratory CO2 release to O2 uptake (RQ) with increasing RGR failed to explain the relatively low root respiration rates in fast-growing grasses. Furthermore, differences in alternative pathway activity can at most only partly explain why the difference in root respiration between fast- and slow-growing grasses is relatively small. Although specific respiratory costs for maintenance of biomass are slightly higher in the fast-growing Dactylis glomerata L. than those in the slow-growing Festuca ovina L., they account for 50% of total root respiration in both species. The specific respiratory costs for ion uptake in the fast-growing grass are one-third of those in the slow-growing grass [0·41 versus 1·22 mol O2 mol (NO3–)–1]. We conclude that this is the major cause of the relatively low rates of root respiration in fast-growing grasses. [ABSTRACT FROM AUTHOR]

Sodium relations of 15 species of Chenopodiaceae were studied in seedlings grown on quartz sand at 10 mol m-3 of sodium and potassium. Uptake of sodium and potassium into whole plants and shoots was followed over 2 weeks. High alkali ion uptake rates were found in all species. The apparent selectivity of alkali ion uptake showed a continuous variation between species, from nearly perfect sodium exclusion to negligible cation selection. K/Na ratios above 6 were found in the shoots of eight species. For most of these plants above ground sodium concentrations were highest in the hypocotyls. However, in Chenopodium hybridum (shoot K/Na = 10) and C. urbicum (shoot K/Na = 17) above ground sodium concentrations were lowest in hypocotyls and highest in leaves, as in those species accumulating larger amounts of sodium. These differences are discussed with respect to the underlying mechanisms of ion regulation. [ABSTRACT FROM AUTHOR]

An equivalent circuit was developed to model the radial electrical coupling between root cells. The results of several experiments were analyzed using the circuit to determine whether the electrogenic pumps of the inner cortical cells were active. This analysis indicated that, while In some roots electrogenic pumps appear to be active in all cortical layers, they may be inactive in the inner cortical cells in some cases. The circuit was used to show that, in spite of intercellular symplasmic coupling, if the inner cortical cells have inactive electrogenic pumps, their membrane potentials can be significantly less negative than those of the epidermal cells. The radial difference in membrane potential may in part account for observations that the uptake of ions occurs primarily on the root periphery. This implication is developed in an appendix to show that an osmotic water pump may exist in roots to allow them to extract water from soil at a lower water potential. It is hypothesized that, as a result of a radial difference in membrane potential, there is an efflux of solutes from the inner cortical cells as the symplastic solution moves inward. As a result, the water potential of the root interior is elevated with respect to its exterior. [ABSTRACT FROM AUTHOR]

Respiration in plants is generally observed to comprise two components: one proportional to the growth rate and the other to the plant dry mass. These components are usually interpreted as being related to the growth of new plant material and maintenance of existing plant material, respectively. By analysing data in this way, the respiratory costs of both structural synthesis and maintenance are observed to be greater in the root than the shoot. This contradicts current understanding of the bio-chemistry of the processes involved. The basic model is developed to incorporate three additional processes. The first is the cost of ion uptake for plant growth. The second allows for the fact that the site of nitrogen assimilation into amino acids may differ from the site of utilization for protein synthesis: when ammonium is supplied, this is incorporated immediately into amino acids owing to its toxicity to the plants: when nitrate is supplied it may be reduced either in the shoot or root, or both, and subsequently transported around the plant for utilization. The third process to be included is an energy cost for the uptake of ions to balance efflux from the root system. The theory is consistent with experimental observation and provides a means of understanding and interpreting respiration and nitrogen metabolism in plants. [ABSTRACT FROM AUTHOR]

An apparatus is described in which water and nutrient uptake (NO3-) and pH were measured and controlled by a microcomputer. Measurements were made twice hourly using appropriate electrodes, both in the nutrient solutions in which the plants were grown and in standard reference solutions. The signals from the electrodes were amplified to a range of 0-10V and were fed to an A/D converter activated by the computer. The needs for water, NO3-, H+ and OH- were then calculated and the necessary adjustments were made to the solutions by automatic injection of the correct amounts to each container in turn. These amounts were records of water and nitrate uptake and pH shift and were saved on disc. The plants were arranged on a turntable which gave additional benefit by smoothing out variations in light intensity. The system allowed a different solution to be maintained for each plant if required. [ABSTRACT FROM AUTHOR]

An increasing literature accounting for various types of experiments indicates that far lower external nutrient concentrations are required by plants than is usually thought to be the case. It is concluded that the ion uptake capacity of the roots, as described by the carrier concept, is high compared to that required for maintenance of the internal concentration. Serious errors in experimental conclusions are associated with insufficient and constant nutrient addition rates. The main errors are caused by non-steady states of the plants both with regard to the internal nutrient concentrations and the relative growth rate. A dynamic concept has been proposed for direct use as the treatment variable within the range of sub-optimum nutrition. The nutritional factor is expressed as a flow, the relative nutrient addition rate in laboratory studies and the nutrient flux density in the field. The experimental use of the relative addition rate has led to steady-state nutrient status and relative growth rate and the interpretation of plant responses which differ fundamentally from accepted views. Thus, for instance, deficiency symptoms disappear, as in natural conditions, when the internal nitrogen concentration is stable, independent of level. The nutrition/growth relationships are very different from those observed when external concentration is varied. The regression line of relative growth rate on relative addition rate passes near to the origin at an angle close to 45° to the axes, which implies that the obtained relative growth rate approximates closely the treatment variable. A striking example of observed differences is the positive effect on nitrogen fixation exerted by high relative nitrogen addition rates compared to the well-known negative effect of increasing external nitrogen concentration. The application of fertilizer on the basis of the nutrient flux density concept provides the possibility of supplying fertilizers corresponding to the consumption pot... [ABSTRACT FROM AUTHOR]

Growth of Sesbania rostrata was decreased gradually with increase in root medium salinity (mixed salts or NaCl alone). Soil moisture or anoxia did not affect plant growth significantly. Higher K+/Na+ ratios in plant tissues compared to those in the root medium were found under different salinities. This indicated a high K+-Na+ selectivity, a characteristic generally considered unique to halophytes. S. rostrata is moderately salt tolerant and may be utilized as forage crop and green manure on saline land. [ABSTRACT FROM AUTHOR]

Increasing NaCl concentration (0, 50, 100 and 150 mM) progressively decreased growth and seed yield of clusterbean (Cyamopsis tetragonoloba Taub.) which was associated with decreased concentrations of potassium and calcium and increased concentration of sodium in the shoots. Supplemental calcium (2.5 and 5.0 mM) significantly ameliorated the adverse effects of NaCl due to enhanced Ca and K uptake and reduced Na uptake. Calcium also alleviated the negative effects of NaCl on activities of nitrogen metabolism enzymes as well as on contents of soluble protein and free amino acids. [ABSTRACT FROM AUTHOR]