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1.
《Process Biochemistry》2007,42(4):710-714
Experiments were conducted in two Aloe vera cultivars (F0 and F50) to study the characters of physiology and ecology under salt stress. The results indicate decreases in tissue water, total soluble sugars and glucose, and increases in dry matter and membrane injury occurred both in F0 and F50 irrigated with 60% seawater. Less cell membrane injury were observed in F50. Moreover, total soluble sugars in F0 decreased obviously, however, no significant change in F50, while sucrose in plants had no significant change. Furthermore, F0 and F50 accumulated more inorganic cations in stems and roots. In addition, leaf K+ and Ca2+ contents were more in F50 than that in F0 to maintain normal plant growth though accumulation of Na+. F50 had a relative superiority in growth under salinity conditions due to higher K+/Na+ ratio and lower Na+/Ca2+ ratio than F0. 相似文献
2.
Wided Megdiche Nader Ben Amor Ahmed Debez Kamel Hessini Riadh Ksouri Yasmine Zuily-Fodil Chedly Abdelly 《Acta Physiologiae Plantarum》2007,29(4):375-384
Though halophytes are naturally adapted to salinity, their salt-tolerance limits are greatly influenced by their provenance
and developmental stage. In the present study, physio-biochemical responses of two Tunisian ecotypes of the oilseed coastal
halophyte Cakile maritima (Brassicaceae) to salinity (0–400 mM NaCl) were monitored during germination and vegetative growth stages. Tabarka and Jerba
seeds were collected from humid or arid climatic areas, respectively. Plant response to salinity appeared to depend on the
ecotype and salinity levels. Increasing salinity inhibited germination process. Jerba seeds were found to be more salt tolerant
than the Tabarka ones. At the autotrophic stage of growth and under salt-free conditions, Jerba was less productive than Tabarka
(in terms of dry matter accumulation), but plant biomass production and leaf expansion (area and number) of the former ecotype
were progressively improved by 100 mM NaCl, as compared to the control. In contrast, at the same salt concentration, these
parameters decreased under increasing salinity in Tabarka (salt sensitive). Leaf chlorophyll content was reduced at severe
salinity, but this effect was more conspicuous in the sensitive Tabarka plants. Na+ contents in the Jerba and Tabarka leaves collected from the 400 mM NaCl-treated plants were 17- and 12-fold higher than in
the respective controls. This effect was accompanied by a significant reduction in the leaf K+, Mg2+ and Ca2+ contents, especially in the salt-treated Tabarka. A significant accumulation of proline and soluble carbohydrates in leaves
was found during the period of intensive leaf growth. These organic compounds likely play a role in leaf osmotic adjustment
and in protection of membrane stability at severe salinity. 相似文献
3.
Effects of sodium chloride on tobacco plants 总被引:7,自引:1,他引:6
Abstract The effect of salinity on the growth and ion concentrations in a number of tobacco cultivars is described. Sodium chloride, at a concentration of 200 mol m?3, hardly affected the fresh weight, but significantly reduced the dry weight. The difference in the response of fresh and dry weights to salt was due to a change in succulence (water per unit leaf area); the latter increased with increasing leaf Na+ and Cl? concentration. Under saline conditions, increasing the external Na+: Ca? ratio by decreasing the Ca2+ concentration increased the accumulation of Na+ and Cl? into the leaf tissue. 相似文献
4.
Effects of seawater salinity (SWS) and pure NaCl on the intracellular contents of Na+, K+, Mg2+, Ca2+, chlorophylls (Chl) and carotenoids (Car) were studied in three submerged aquatic macrophytes, Hydrilla verticillata, Najas indica and Najas gramenia, which differed in their tolerance to salinity. NaCl resulted in significant increase in Chl/Car ratio in the salt-sensitive H. verticillata and moderately salt-tolerant N. indica, but not in the salt-tolerant N. gramenia. SWS treatment did not result in any significant change in the ratio. The intracellular content of Na+ increased significantly in all the test plants upon exposure to both NaCl and SWS. The content of K+ decreased significantly in these plants upon salinity treatment, except in N. gramenia. The contents of Ca2+ and Mg2+ decreased significantly upon NaCl treatment and remained unchanged or increased upon SWS treatment. No relationship between salt tolerance and K+/Na+ ratio was observed. The maintenance of a minimal level of K+ was observed to be the most probable requirement of salt tolerance in aquatic macrophytes. 相似文献
5.
M.A.A. Gadallah 《Biologia Plantarum》1999,42(2):249-257
Plants of bean (Vicia faba L. cv. Calvor 103) were salt-stressed with NaCl and CaCl2 in concentrations inducing soil osmotic potentials (ψsoil) from 0 to -1.2 MPa and were sprayed with proline (8.7 μM) and glycinebetaine (8.5 μM) solutions. Bean plants respond to
increasing soil salinity by decreased leaf relative water content and osmotic potential. Salinity decreased the contents of
dry mass, chlorophyll, soluble and hydrolysable sugars, soluble proteins and enhanced content of total free amino acids, Na+, Ca2+ and Cl-. The ratio of K+/Na+ was decreased on salinization. The membranes of leaf discs from salt-stressed plants appeared to be less stable under heat
stress (51 °C) than that of unstressed plants. The reverse was true for discs placed under dehydration stress (40 % polyethylene
glycol 6000). Proline and glycinebetaine application reduced membrane injury, improved K+ uptake and growth. Also both solutes increased chlorophyll contents.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
The effects of NaCl (0, 50, 100, 150 and 200 mM) on growth, water relations, glycinebetaine, free proline, ion contents, stomata number and size of Kochia prostrata (L.) Schard were determined. Shoot and root fresh and dry matter, root and shoot length, relative growth rate, net assimilation rate, relative water content, water use efficiency, soluble sugars and glycinebetaine contents were not changed at low NaCl concentrations, but they were significantly decreased at 200 mM NaCl. The K+, Mg2+ and Ca2+ contents, water potential, chlorophyll a+b and carotenoides contents, and stomata number and size were reduced already at low concentrations of NaCl. In contrast, the Na+, Cl– and proline contents increased several times with increasing NaCl concentration. Kochia prostrata is a salt tolerant species, the optimal growth of this plant occurred up to 150 mM NaCl. The mechanisms of salt tolerance in the plant may be balance among ion accumulation and production of glycinebetaine, proline, soluble sugars for maintenance of pressure potential. 相似文献
7.
Effect of grain soaking presowing in 1 mM salicylic acid (SA) and NaCl (0, 50, 100, 150 and 200 mM) on barley (Hordeum vulgare cv Gerbel) was studied. Increasing of NaCl level reduced the germination percentage, the growth parameters (fresh and dry weight), potassium, calcium, phosphorus and insoluble sugars content in both shoots and roots of 15-day old seedlings. Leaf relative water content (RWC) and the photosynthetic pigments (Chl a, b and carotenoids) contents also decreased with increasing NaCl concentration. On the other hand, Na, soluble sugars, soluble proteins, free amino acids including proline content and lipid peroxidation level and peroxidase activity were increased in the two plant organs with increasing of NaCl level. Electrolyte leakage from plant leaves was found to increase with salinity level. SA-pretreatment increased the RWC, fresh and dry weights, water, photosynthetic pigments, insolube saccharides, phosphorus content and peroxidase activity in the stressed seedlings. On the contrary, Na+, soluble proteins content, lipid peroxidation level, electrolyte leakage were markedly reduced under salt stress with SA than without. Under stress conditions, SA-pretreated plants exhibited less Ca2+ and more accumulation of K+, and soluble sugars in roots at the expense of these contents in the plant shoots. Exogenous application (Grain soaking presowing) of SA appeared to induce preadaptive response to salt stress leading to promoting protective reactions to the photosynthetic pigments and maintain the membranes integrity in barley plants, which reflected in improving the plant growth. 相似文献
8.
Effect of NaCl on Biomass and Contents of Sugars, Proline and Proteins in Seedlings and Leaf Explants of Nicotiana tabacum Grown in vitro 总被引:2,自引:2,他引:0
Effects of NaCl on growth in vitro and contents of sugars, free proline and proteins in the seedlings and leaf explants of Nicotiana tabacum cv. Virginia were investigated. The fresh and dry mass of the seedlings decreased under salinity. These growth parameters in leaf explants decreased at 50 mM NaCl and increased up to 150 mM NaCl and then decreased at higher level of salinity. Free proline content in both seedlings and leaf explants increased and polysaccharide content decreased continuously with increasing of NaCl concentration. Reducing sugars, oligosaccharides, soluble sugars and total sugars contents in both seedlings and leaf explants decreased up to 150 mM NaCl and then increased at higher concentrations of NaCl. 相似文献
9.
Growth and Na+, K+, Cl-, proteins, sugars and proline concentrations were measured in three triticale genotypes M2A, DF99 and Asseret grown on nutrient
solution with or without 75 mM NaCl. In saline conditions, leaf area of the three triticales was reduced by 50 % and dry to
fresh mass ratio increased. Total protein concentration was diminished by 10 %. K+ concentration decreased whereas Na+ and Cl- accumulated in roots and shoots of salt-stressed plants. This ion accumulation was greater in roots of Asseret than in roots
of the other triticales. Soluble sugar concentration increased in M2A and Asseret and decreased in DF99. Proline concentration
increased in M2A and DF99 and decreased in Asseret. Osmotic adjustment was essentially realized by Na+ and Cl- uptake. Non-reducing sugars and proline contributed too, but to a lesser extent.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
A. M. Hamada 《Biologia Plantarum》1996,38(3):405-412
Responses of wheat (Triticum aestivum L.) to various concentrations of NaCl and levels of drought were followed. With the rise of NaCl or drought, or NaCl and
drought together, growth was retarded. The water content of shoots and roots was mostly unchanged. The chlorophyll and carotenoid
contents were increased in plants subjected to salinity or drought or both. Only high salinity level induced a considerable
decrease in net photosynthetic rate (PN) and dark respiration rate (RD). PN and RD were decreased with the decrease of soil moisture content. The content of Na+ in the shoots and roots of wheat plants increased with increasing salinity or decreasing soil moisture content or both treatments.
Considerable variations in the content of K+, Ca2+ or Mg2+ were induced by the NaCl, drought or both treatments. 相似文献
11.
Counteraction of Salinity Stress on Wheat Plants by Grain Soaking in Ascorbic Acid, Thiamin or Sodium Salicylate 总被引:12,自引:0,他引:12
The interactive effects of salinity stress (40, 80, 120 and 160 mM NaCl) and ascorbic acid (0.6 mM), thiamin (0.3 mM) or sodium salicylate (0.6 mM) were studied in wheat (Triticum aestivum L.). The contents of cellulose, lignin of either shoots or roots, pectin of root and soluble sugars of shoots were lowered with the rise of NaCl concentration. On the other hand, the contents of hemicellulose and soluble sugars of roots, starch and soluble proteins of shoots, proline of either shoots or roots, and amino acids of roots were raised. Also, increasing NaCl concentration in the culture media increased Na+ and Ca2+ accumulation and gradually lowered K+ and Mg2+ concentration in different organs of wheat plant. Grain soaking in ascorbic acid, thiamin or sodium salicylate could counteract the adverse effects of NaCl salinity on the seedlings of wheat plant by suppression of salt stress induced accumulation of proline. 相似文献
12.
Effect of soil salinity was studied in two maize (Zea mays L.) genotypes, DTP-w-c 9 (comparatively tolerant) and Prabhat (susceptible) under control and three levels of salinity at
vegetative and anthesis stages during summer–rainy season. Salinity stress decreased relative water content (RWC), chlorophyll
(Chl) and carotenoid (Car) contents, membrane stability index (MSI), potassium (K+) and calcium (Ca2+) contents, and increased the rate of superoxide radical (O2·−) production, contents of hydrogen peroxide (H2O2), thiobarbituric acid reactive substances (TBARS) (measure of lipid peroxidation), proline, glycine-betaine, total soluble
sugars, sodium (Na+), and Na+/K+ and Na+/Ca2+ ratios in both the genotypes. Activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and glutathione
reductase (GR) increased up to S2 salinity level in both the genotypes, and up to highest salinity level (S3) in DTP-w-c 9 at the two stages. Salinity-induced decrease in RWC, Chl, Car, MSI, K+ and Ca2+ was significantly greater in Prabhat, which also recorded higher Na+ content and Na+/K+ and Na+/Ca2+ ratios than DTP-w-c 9. DTP-w-c 9 recorded higher contents of proline, glycine-betaine, total soluble sugars, K+, Ca2+, activity of SOD, APX, CAT, GR, and comparatively lower O2·−, H2O2 and TBARS contents compared to Prabhat. Results show that salinity tolerance of DTP-w-c 9, as manifested by less decrease
in RWC, Chl, Car and MSI, is associated with maintenance of adequate levels of K+ and Ca2+, greater contents of osmolytes, higher antioxidant enzymes activity, and lower O2·−, H2O2, TBARS and Na+ contents than Prabhat. 相似文献
13.
Exogenous proline effects on water relations and ions contents in leaves and roots of young olive 总被引:1,自引:0,他引:1
Ch. Ben Ahmed S. Magdich B. Ben Rouina S. Sensoy M. Boukhris F. Ben Abdullah 《Amino acids》2011,40(2):565-573
The ability of exogenous compatible solutes, such as proline, to counteract salt inhibitory effects was investigated in 2-year-old
olive trees (Olea europaea L. cv. Chemlali) subjected to different saline water irrigation levels supplied or not with exogenous proline. Leaf water
relations [relative water content (RWC), water potential], photosynthetic activity, leaf chlorophyll content, and starch contents
were measured in young and old leaves. Salt ions (Na+, K+, and Ca2+), proline and soluble sugars contents were determined in leaf and root tissues. Supplementary proline significantly mitigated
the adverse effects of salinity via the improvement of photosynthetic activity (Pn), RWC, chlorophyll and carotenoid, and
starch contents. Pn of young leaves in the presence of 25 mM proline was at 1.18 and 1.38 times higher than the values recorded
under moderate (SS1) and high salinity (SS2) treatments, respectively. Further, the proline supply seems to have a more important
relaxing effect on the photosynthetic chain in young than in old leaves of salt-stressed olive plants. The differential pattern
of proline content between young and old leaves suggests that there would be a difference between these tissues in distinguishing
between the proline taken from the growing media and that produced as a result of salinity stress. Besides, the large reduction
in Na+ accumulation in leaves and roots in the presence of proline could be due to its interference in osmotic adjustment process
and/or its dilution by proline supply. Moreover, the lower accumulation of Na+ in proline-treated plants, compared to their corresponding salinity treatment, displayed the improved effect of proline on
the ability of roots to exclude the salt ions from the xylem sap flowing to the shoot, and thus better growth rates. 相似文献
14.
The salt tolerance of peanut (Arachis hypogaea L.) seedlings was evaluated by analyzing growth, nutrient uptake, electrolyte leakage, lipid peroxidation and alterations in levels of some organic metabolites under NaCl stress. The plant height, leaf area and plant biomass decreased significantly in salt-treated seedlings as compared with control. The relative water content (RWC %) of leaf decreased by 16 % at high concentrations of NaCl. There was an increase in the lipid peroxidation level and decrease in the electrolyte leakage at high concentrations of NaCl. The total free amino acid and proline contents of leaf increased by 5.5- and 43-folds, respectively in 150 mM NaCl-treated plants as compared with control. Total sugar and starch content increased significantly at high concentrations of NaCl. Chl a, Chl b, total chlorophyll and carotenoid contents decreased significantly at high salinity. Na+ contents of leaf, stem and root increased in dose-dependent manner. K+ content remained unaffected in leaf and root and decreased in stem by salinity. The results from present study reveal that the peanut plants have an efficient adaptive mechanism to tolerate high salinity by maintaining adequate leaf water status associated with growth restriction. In order to circumvent the stress resulting from high salinity, the levels of some organic metabolites such as total free amino acids, proline, total sugars and starch were elevated. The elevated levels of the organic metabolites may possibly have some role in maintenance of osmotic homeostasis, nutrient uptake and adequate tissue water status in peanut seedlings under high-salinity conditions. 相似文献
15.
A. Zrig T. Tounekti H. BenMohamed H. Abdelgawad A. M. Vadel D. Valero H. Khemira 《Russian Journal of Plant Physiology》2016,63(1):143-151
It was examined how essential cations, Ca2+ and K+, can mitigate the toxic effects of NaCl on two different almond species (Prunus amygdalus Batsch) rootstocks, Garnem (GN15) and Bitter Almond. The tree growth parameters (water potential (Ψw), gas exchange, nutrient uptake) and leaf chlorophyll (Chl) content were measured in control and NaCl-treated plants with or without KCl or CaCl2 supplements. The addition of CaCl2 and KCl to Bitter Almond trees reduced their dry weight, shoot growth and leaf number although net photosynthetic assimilation rate (A) was not affected. These results indicated that changing of photo-assimilates flux to proline and/or soluble sugars synthesis may help to increase leaf Ψw. The Garnem trees also did not respond to the CaCl2 and KCl addition indicating that the plants are already getting enough of these two cations (Ca2+ and K+). In both rootstocks, NaCl in the medium reduced growth attributes, Ψw, A, stomatal conductance (gs), and leaf Chl content. When CaCl2 and KCl fertilizers were added together with NaCl to Bitter Almond trees, leaf K+ and Ca2+ contents increased while Na+ and Cl– decreased leading to higher Ca/Na and K/Na ratios, but shoot growth was not improved and even declined compared to NaCl-treated trees. It appears that the addition of salts further aggravated osmotic stress as indicated by the accumulation of proline and soluble sugars in leaf tissues. The addition of KCl or CaCl2 to NaCl-treated GN15 trees did not increase A, leaf Ψw, and shoot growth but improved ionic balances as indicated by higher Ca/Na and K/Na ratios. The reduction in A was mainly due to non-stomatal limitations in GN15, possibly due to the degradation of Chl a, unlike Bitter Almond, for which the reduction of A was due to stomata closure. The improvement in ionic balances and water status of Bitter Almond trees in response to addition of KCl or CaCl2 was apparently offset by a high sensitivity to Cl–; therefore, no-chloride salts should be the preferred forms of fertilizers for this rootstock. Both rootstocks were sensitive to soil salinity and cation supplements were of limited value in mitigating the effect of excessive salt concentrations. 相似文献
16.
Salinity causes changes in cytosolic Ca2+, [Ca2+]cyt, Na+, [Na+]cyt and pH, pHcyt, which induce specific reactions and signals. Reactions causing a rebalancing of the physiological homeostasis of the cytosol could result in plant resistance and growth. Two wheat cultivars, Triticum aestivum, Seds1 and Vinjett, were grown in nutrient solution for 7 days under moderate salinity (0 and 50 mM NaCl) with and without extra addition of 5 mM CaSO4 to investigate the seedling‐ion homeostasis under salinity. In the leaf protoplasts [Ca2+]cyt, [Na+]cyt and pHcyt were detected using acetoxymethyl esters of the ion‐specific dyes, Fura 2, SBFI and BCECF, respectively, and fluorescence microscopy. In addition, both cultivars were grown for 3 weeks at 0, 50 and 125 mM NaCl with, or without, extra addition of 5 mM CaSO4 to detect overall Na+ and Ca2+ concentrations in leaves and salinity effects on dry weights. In both cultivars, salinity decreased [Ca2+]cyt, while at extra Ca2+ supplied, [Ca2+]cyt increased. The [Ca2+]cyt increase was accompanied by increase in the overall Ca2+ concentrations in leaves and decrease in the overall Na+ concentration. Moreover, irrespective of Ca2+ treatment under salinity, the cultivars reacted in different ways; [Na+]cyt significantly increased only in cv. Vinjett, while pHcyt increased only in cv. Seds1. Even at rather high total Na+ concentrations, the cytosolic concentrations were kept low in both cultivars. It is discussed whether the increase of [Ca2+]cyt and pHcyt can contribute to salt tolerance and if the cytosolic changes are due to changes in overall Ca2+ and Na+ concentrations. 相似文献
17.
Can elevated CO(2) improve salt tolerance in olive trees? 总被引:2,自引:0,他引:2
We compared growth, leaf gas exchange characteristics, water relations, chlorophyll fluorescence, and Na+ and Cl− concentration of two cultivars (‘Koroneiki’ and ‘Picual’) of olive (Olea europaea L.) trees in response to high salinity (NaCl 100 mM) and elevated CO2 (eCO2) concentration (700 μL L−1). The cultivar ‘Koroneiki’ is considered to be more salt sensitive than the relatively salt-tolerant ‘Picual’. After 3 months of treatment, the 9-month-old cuttings of ‘Koroneiki’ had significantly greater shoot growth, and net CO2 assimilation (ACO2) at eCO2 than at ambient CO2, but this difference disappeared under salt stress. Growth and ACO2 of ‘Picual’ did not respond to eCO2 regardless of salinity treatment. Stomatal conductance (gs) and leaf transpiration were decreased at eCO2 such that leaf water use efficiency (WUE) increased in both cultivars regardless of saline treatment. Salt stress increased leaf Na+ and Cl− concentration, reduced growth and leaf osmotic potential, but increased leaf turgor compared with non-salinized control plants of both cultivars. Salinity decreased ACO2, gs, and WUE, but internal CO2 concentrations in the mesophyll were not affected. eCO2 increased the sensitivity of PSII and chlorophyll concentration to salinity. eCO2 did not affect leaf or root Na+ or Cl− concentrations in salt-tolerant ‘Picual’, but eCO2 decreased leaf and root Na+ concentration and root Cl− concentration in the more salt-sensitive ‘Koroneiki’. Na+ and Cl− accumulation was associated with the lower water use in ‘Koroneiki’ but not in ‘Picual’. Although eCO2 increased WUE in salinized leaves and decreased salt ion uptake in the relatively salt-tolerant ‘Koroneiki’, growth of these young olive trees was not affected by eCO2. 相似文献
18.
Guo-Qiang Wu Na Liang Rui-Jun Feng Jing-Jing Zhang 《Acta Physiologiae Plantarum》2013,35(9):2665-2674
Salinity tolerance of sugar beet (Beta vulgaris L.) cultivars in terms of growth, proline and soluble sugars concentrations, and Na+/K+ and Na+/Ca2+ ratios were analyzed in this study. Three-week-old seedlings of three sugar beet cultivars, ‘Gantang7’, ‘SD13829’, and ‘ST21916’, differing in salinity tolerance, were treated with 0, 50, 100, and 200 mM NaCl. Plant shoots and roots were harvested at 7 days after treatment and subjected to analysis. Low concentration of NaCl (50 mM) enhanced fresh and dry weights of shoot and root in ‘Gantang7’, whereas high one (200 mM) reduced growth in all cultivars and the less reduction was observed in ‘ST21916’. Shoot proline was strongly induced by salinity stress in both ‘Gantang7’ and ‘SD13829’, while it remained unchanged in ‘ST21916’. The addition of 50 mM NaCl significantly increased shoot soluble sugars concentrations in ‘Gantang7’ while it had no significant effects in the other two cultivars. ‘Gantang7’ also showed a higher level of root soluble sugars concentration as compared to the other two cultivars. At 50 mM NaCl, the lower shoot Na+ concentration, and the higher shoot K+ and root Ca2+ concentration in ‘Gantang7’ resulted in the lower shoot Na+/K+ and root Na+/Ca2+ ratio. However, ‘SD13829’ maintained a lower Na+/K+ ratio in both shoot and root when subjected to 200 mM NaCl treatment. According to comprehensive evaluation on salinity tolerance, it is clear that ‘Gantang7’ is more tolerant to salinity than the other two cultivars. Therefore, it is suggested that ‘Gantang7’ should be more suitable for cultivating in the arid and semi-arid irrigated regions. 相似文献
19.
Tobacco plants (Nicotiana tabacum L. cv. Sevilla) were grown under controlled conditions. The leaf content of Ca2+, Mg2+ and K+, and the activity of the pyruvate kinase were analyzed. The increased application of Ca2+ diminished the content of K+ and Mg2+ in leaves, and decreased the activity of pyruvate kinase. Taking into account these results, we suggest the pyruvate kinase activity as an bioindicator of the contents of the Ca2+, Mg2+ and K+. 相似文献
20.
Influx of na, k, and ca into roots of salt-stressed cotton seedlings : effects of supplemental ca
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High Na+ concentrations may disrupt K+ and Ca2+ transport and interfere with growth of many plant species, cotton (Gossypium hirsutum L.) included. Elevated Ca2+ levels often counteract these consequences of salinity. The effect of supplemental Ca2+ on influx of Ca2+, K+, and Na+ in roots of intact, salt-stressed cotton seedlings was therefore investigated. Eight-day-old seedlings were exposed to treatments ranging from 0 to 250 millimolar NaCl in the presence of nutrient solutions containing 0.4 or 10 millimolar Ca2+. Sodium influx increased proportionally to increasing salinity. At high external Ca2+, Na+ influx was less than at low Ca2+. Calcium influx was complex and exhibited two different responses to salinity. At low salt concentrations, influx decreased curvilinearly with increasing salt concentration. At 150 to 250 millimolar NaCl, 45Ca2+ influx increased in proportion to salt concentrations, especially with high Ca2+. Potassium influx declined significantly with increasing salinity, but was unaffected by external Ca2+. The rate of K+ uptake was dependent upon root weight, although influx was normalized for root weight. We conclude that the protection of root growth from salt stress by supplemental Ca2+ is related to improved Ca-status and maintenance of K+/Na+ selectivity. 相似文献