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1.
《Journal of plant nutrition》2013,36(8):1441-1452
Abstract

Saltgrass [Distichlis spicata (L.) Greene var. stricta (Gray) Beetle], accession WA-12, collected from a salt playa in Wilcox, AZ, was studied in a greenhouse to evaluate its growth responses in terms of shoot and root lengths, shoot dry-matter yield, and nitrogen (N) (regular and 15N) absorption rates under control and salt (sodium chloride, NaCl) stress conditions. Plants were grown under a control (no salt) and three levels of salt stress (100, 200, and 400 mM NaCl, equivalent to 5850, 11700, and 23400 mg L? 1 sodium chloride, respectively), using Hoagland solution in a hydroponics system. Ammonium sulfate [(15NH4)2SO4], 53% 15N (atom percent 15N) was used to enrich the plants. Plant shoots were harvested weekly, oven-dried at 60°C, and the dry weights measured. At each harvest, both shoot and root lengths were also measured. During the last harvest, plant roots were also harvested and oven-dried, and dry weights were determined and recorded. All harvested plant materials were analyzed for total N and 15N. The results showed that shoot and root lengths decreased under increasing salinity levels. However, both shoot fresh and dry weights significantly increased at 200 mM NaCl salinity relative to the control or to the 400 mM NaCl level. Shoot succulence (fresh weight/dry weight) also increased from the control (no salt) to 200 mM NaCl, then declined. The root dry weights at both 200 mM and 400 mM NaCl salinity levels were significantly higher than under the control. Concentrations of both total-N and 15N in the shoots were higher in NaCl-treated plants relative to those under the control. Shoot total-N and 15N contents were highest in 200 mM NaCl-treated plants relative to those under the control and 400 mM salinity.  相似文献   

2.
《Journal of plant nutrition》2013,36(8):1365-1374
ABSTRACT

Salt tolerance of Arthrocnemum macrostachyum (Moric.) C. Koch (Chenopodiaceae), a stem-succulent halophyte most commonly found in the intertidal regions of the provinces of Sind and Balochistan, Pakistan, was investigated. Plants were grown for 125 d at six sodium chloride (NaCl) concentrations from 0 to 1000 mM to determine the effects of salinity on ion accumulation, plant water status, and biomass. Shoot biomass was greatest at 200 to 400 mM NaCl, but it was inhibited at salinities of 600 mM NaCl or higher. Tissue water content (g g?1dry mass) of shoots under 200 to 600 mM NaCl treatments was higher than under the control nutrient solution, equal to the control at 800 mM NaCl, but significantly lower at 1000 mM NaCl than under all other treatments, indicating an increase in shoot succulence at salinity levels up to that of seawater. Ash content increased with added salt, but was about 60% of plant dry mass under all salinity treatments. The Na+ and Cl? concentrations of shoots were significantly higher under 1000 mM NaCl than under the control treatment. These results indicate that A. macrostachyum is salt tolerant and capable of accumulating large quantities of Na+ and Cl? when treated with from 200 to 1000mM NaCl.  相似文献   

3.
The growth of the halophyte Sesuvium portulacastrum, commonly known as sea purslane, is impeded by NaCl only at high (600–1000 mM) concentration. Therefore, the goal of this investigation was to identify the mechanisms which set the limit of the salt resistance of S. portulacastrum. 21‐day‐old cuttings were grown for 45–50 d under split‐root conditions in which one half of the root system was immersed in complete nutrient solution supplemented with 800 mM NaCl, while the other half was immersed in a NaCl‐free medium, containing all nutrients or being deprived of potassium or calcium or nitrogen. Using this approach, we demonstrate that K+ and N uptake was impaired in roots exposed to NaCl. Concerning Ca2+, there was no indication of uptake inhibition by NaCl. However, restriction of K+ uptake by roots was compensated by an increase in the K+‐use efficiency, so that growth was not inhibited. Concerning N, our analysis shows that NO and/or NH uptake, but not their assimilation, was limited by salt treatment. Thus, we conclude that at high salinity levels, the growth of S. portulacastrum is limited by the restrictions imposed by NaCl on N uptake, perhaps in addition to inhibiting effects of excessive Na+ accumulation in shoot.  相似文献   

4.
The Interaction between the effects of nitrate (NO3) and sodium chloride (NaCl) concentration on growth) water relations, nitrogen (N) contents and N fixation were investigated in alfalfa (Medicago sativa L. cv. Magali). The plants were grown hydroponically in a growth chamber, in the presence or absence of 3 mM potassium nitrate (KNO3) and exposed to various concentrations of NaCl. Increased salinity resulted in a significant decrease in shoot and root biomass, relative water content and water potential. Shoot growth was more inhibited by NaCl than root biomass. The plants grown in the presence of NO3 were slightly less affected by NaCl than the plants dependent on N fixation for their N nutrition. Nitrogenase activity measured by acetylene reduction activity was substantially inhibited by NaCl, and this inhibition was significantly correlated to the inhibition of shoot growth and total N contents. The comparison of the curves of ARA response to oxygen (O2) partial pressure showed that the salt‐induced inhibition of nitrogenase activity was associated with a significant increase in the critical O2 pressure of the nodules exposed to NaCl. This result shows that NaCl decreases the nodule permeability to O2 diffusion in undeterminate nodule of alfalfa, like previously shown with determinate nodules of soybean.  相似文献   

5.
Abstract

This study was conducted to evaluate the effect of vesicular‐arbuscular mycorrhizal (VAM) fungus Glomus etunicatum on growth, absorption, and distribution of calcium (Ca), magnesium (Mg), phosphorus (P), and aluminum (Al) in one Al‐tolerant and one Al‐sensitive barley cultivar. The plants were grown in sand daily irrigated with nutrient solution containing 0 or 600 μM Al at pH 4.8. Significant interaction (P=0.05) among variety, mycorrhiza, and aluminum (VxMxAl) were noted for both shoot and root dry matter (DM); shoot concentration and content of Al, P, Ca, and Mg; root concentration of Al, P, and Mg; and root content of Al, P, Ca, and Mg. With VAM inoculation: i) root colonization degree was about 50% in all treatment, ii) shoot DM yield increased between 30 and 70%, iii) Al concentration and content decrease down to a half both in shoots and roots of sensitive barley, iv) Ca concentration in shoots of sensitive barley showed a high increase at 600 μM Al, and v) P concentration and content in shoots of both varieties increased significantly.  相似文献   

6.
An investigation was conducted to determine the effect of potassium (K) nutrition on alfalfa (Medicago sativa L.) growth and metabolism of root total nonstructural carbohydrates (TNC) and proteins, and to study whether nitrogen (N) fertilization overcomes N deficiency and low root protein concentrations caused by K deficiency. In Experiment 1, nodulated alfalfa plants were grown in plastic pots containing washed quartz sand and provided minus‐N Hoagland's solution containing 0, 0.6, or 6.0 mM K. Shoot and root K concentrations increased with increasing solution K. Root N concentrations were higher in plants receiving 6.0 mM K than in plants receiving 0.6 or 0 mM K, but shoot N concentrations were similar for all treatments. Plant persistence, shoots per plant, and shoot mass increased as solution K levels increased. Root starch concentration and utilization were positively associated with K nutrition. Total amylase activity was higher, but endoamylase activity was lower in roots of plants receiving 6.0 mM K compared to plants receiving 0.6 or 0 mM K. Root soluble protein concentrations were significantly higher in plants receiving 6.0 mM K than in plants receiving 0 or 0.6 mM K. In Experiment 2, plants were supplied with Hoagland's solution containing 10 mM N as ammonium (NH4 +) or nitrate (NO3) with 0,3, or 6.0 mM K. The addition of N increased root N concentrations only in plants receiving 0 mM K. Plant persistence was reduced by NH4 + application, especially in plants receiving 0 or 3 mM K. Root starch concentrations were markedly reduced in plants receiving NH4 + at all K levels. The addition of NO3 ‐ had little effect on alfalfa root carbohydrate and protein metabolism and subsequent shoot growth. Potassium deficiency reduced starch and protein concentrations in roots; factors that were associated with poor persistence and slow shoot regrowth of alfalfa.  相似文献   

7.
Maize (Zea mays L.) plants in the early stage of development were treated with 80 mM sodium chloride (NaCl) with or without supplemental calcium (Ca2+) (8.75 mM) for a seven day period. The effects of salinity on dry matter production and shoot and root concentrations of sodium (Na+), Ca2+, and potassium (K+) were measured for seven Pioneer maize cultivars. Salinity significantly reduced total dry weight, leaf area, and shoot and root dry weight below control levels. For all seven cultivars, Na+concentrations were reduced and leaf area was significantly increased by supplementing salinized nutrient solutions with 8.75 mM calcium chloride (CaCl2). The two cultivars with the lowest shoot and root Na+ concentrations under NaCl‐salinity showed the greatest increases in total, shoot and root dry weights with the addition of supplemental Ca. Shoot fresh weight/dry weight ratios for all cultivars were decreased significantly by both salinity treatments, but supplemental Ca2+ increased the ratio relative to salinity treatments without supplemental Ca. Root fresh weight/dry weight ratios were decreased only by salinity treatments with supplemental Ca. With NaCl‐salinity, cultivars which had lower shoot and root Na+ concentrations were found to be more salt sensitive and had significantly lower amounts of dry matter production than those cultivars which had higher shoot and root Na+ concentrations. It was concluded that Na+ exclusion from the shoot was not correlated with and was an unreliable indicator of salt tolerance for maize.  相似文献   

8.
Certain organic constituents, amino acids, protein, proline, glycinebetaine, sugars, and starch in the leaves of Sesuvium portulacastrum, which was grown under varying levels of sodium chloride (NaCl) was determined. Total amino acids lowered at increasing levels of NaCl while the protein content increased moderately up to 600 mM and thereafter increased and decreased, respectively; however, 600 mM level of NaCl significantly differed from the untreated control plants. The concentration of total sugars declined with the increasing levels of exogenous addition of NaCl up to 600 mM. Starch content increased significantly up to 600 mM NaCl and thereafter declined slightly. Proline and glycinebetaine contents were accumulated with the corresponding increase of salinization.  相似文献   

9.
《Journal of plant nutrition》2013,36(5):1131-1148
Abstract

Cogenerational phenotypic plasticity compensation to nutrient limitations and shoot densities (light limitation) among individual plants of the same species could provide an increased fitness. Planting density varying between 4 and 16 plants per container and solution nitrogen varying between 5 and 19 mM were used to test phenotypic plastic responses in oat (Avena sativa cv. Montezuma) seed biochemistry and the resulting progeny. Seed Kjeldahl nitrogen (N), magnesium (Mg), and both albumin–globulin (l M NaCl soluble) and prolamin–glutelin (residue) protein fractions were affected by a solution N × plant density interaction. Phosphorus (P) content was influenced by both treatment variables. The protein fractions, P, N, and Mg, in seeds from parent treatments were generally highest in the two higher planting densities. The contents of N, P, Mg, and the prolamin–glutelin fraction were highest at mid‐N (9 mM), except for the 16 plants per container where they were maximal at high‐N (19 mM). In contrast, the albumin–globulin fraction responded linearly to N availability. Seeds per plant decreased while seed weights increased, as plant density increased. The seed content of N, albumin–globulin, prolamin–glutelin, P, and Mg were all negatively associated with the number of seeds per plant. Germination rates of progeny were inversely related to parent plants N treatment. Progeny from the treatment plants (seeds × germination percent) were inversely related, over a five‐fold range, to parent density. Progeny shoot/root ratios (S/R) were directly influenced by the N treatment of parent plants, with progeny from the highest parent N treatment having the highest S/R. Seed N and P content and the prolamin–glutelin protein fraction concentration were correlated with progeny SR. Seed weight was negatively correlated with progeny S/R. Annual grass seed numbers and weights and the allocation of several seed constituents are environmentally influenced by plant density and solution N. These seed biochemical and physiological effects result in a reproductive fitness change and a cogenerational phenotypic plasticity influenced progeny fitness (S/R attribute).  相似文献   

10.
Plant growth promoting effects of Bacillus subtilis EY2, Bacillus atrophaeus EY6, Bacillus spharicus GC subgroup B EY30, Staphylococcus kloosii EY37 and Kocuria erythromyxa EY43 were tested on strawberry cv. ‘Fern’ in terms of fruit yield, growth, chlorophyll reading value, leaf relative water content (LRWC), membrane permeability and ionic composition of leaves and roots under saline conditions. Compared with 0 mM sodium chloride (NaCl) treatment, the average decrease of yield and LRWC were 51.6% and 21.0%, respectively, when 35 mM NaCl was applied. However, EY30, EY37, and EY43 treatments under saline condition (35 mM NaCl) significantly increased fruit yield (54.4%, 51.7% and 94.9%) compared with 35 mM NaCl treatment without plant growth promoting bacteria (PGPB). The LRWC increased from 72.0% in 35 mM NaCl treatment to 88.4%, 86.6%, 84.2%, 83.5%, and 86.2% by EY2, EY6, EY30, EY37, and EY43 applications, respectively. The lowest membrane permeability among the bacterial strains was obtained from EY37 treatment (37) while it was 33 and 58 in 0 mM NaCl and 35 mM NaCl treatments, respectively. The concentration of all plant tissue nutrients investigated [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)] with the exception of root phosphorus (P) and Mg concentration significantly decreased with 35 mM salt treatment. Nitrogen content of leaves varied between 3.04 and 3.14% in bacterial treatments under saline conditions while it was 2.71% in 35 mM NaCl treatment. In contrast sodium (Na) and chloride (Cl) of leaves and Cl content of roots were significantly decreased by root inoculation with all bacterial treatments in comparison to 35 mM NaCl treatment with no inoculation. Treatment with Bacillus EY30, Staphylococcus EY37 and Kocuria EY43 to strawberry plants can ameliorative the deleterious effect of salt stress on fruit yield, growth and nutrition. These results demonstrate that PGPB treatment could be offer an economic and simple means to increased plant resistance for salinity stress.  相似文献   

11.
Maize plants (Zea mays L. cv. Pioneer 3906) were grown in hydroponics with four different NaCl treatments (control, 50, 100, 150 mM NaCl). Nitrogen (N) was supplied as 2 mM Ca(NO3)2 in the fully concentrated nutrient solution. Plants of half of the pots were treated with additional 1 mM NH4NO3 2 d after start of the NaCl application. After 23 d, the maize plants were harvested and contents and concentrations of nitrate, reduced N as well as chloride were determined in shoots and roots. With increasing NaCl stress net nitrate uptake and net root‐to‐shoot translocation of total N decreased significantly. Under salt stress, decreased nitrate concentrations in shoots probably caused substrate limitation of nitrate reductase. However, the concentrations of reduced N in shoots were not affected by salt stress and no N deficiency was observed. Additional N application to the 100 and 150 mM NaCl treatments did not improve plant growth. A Cl?/NO antagonism was only weakly pronounced, probably because of the Cl? exclusion ability of maize. Thus, although net uptake and net translocation of total N were markedly decreased by NaCl application, the smaller maize plants nevertheless took up enough N to meet their demand pointing to other growth‐limiting factors than N nutrition.  相似文献   

12.
The effect of varying hydrogel (0, 0.5, and 1.0% w/w) supply on some agro-physiological properties, such as dry matter, nutrient contents, chlorophyll contents, proline content, and ionic balance of bean plants in different salt sources and stress due to doses were investigated. Plants were treated with eight salt sources [sodium chloride (NaCl), sodium sulfate (Na2SO4), calcium chloride (CaCl2), calcium sulfate (CaSO4), potassium chloride (KCl), potassium sulfate (K2SO4), magnesium chloride (MgCl2), magnesium sulfate (MgSO4)] and four concentrations (0, 30, 60, and 120 mM doses) for 60 days in a growth media. Salt type, doses, and hydrogel (HG) affected the soil electrical conductivity. Soil salinity affected the parameters considered, and changed the nutrient balance of plants. High salt concentration caused substantial reduction in plant growth. Different salt concentrations negatively affected plant dry weight. The highest decrease of plant root dry weight was obtained with NaCl application followed by Na2SO4, CaCl2, CaSO4, MgCl2, MgSO4, KCl, and K2SO4, and similarly NaCl, Na2SO4, CaCl2, CaSO4, KCl, K2SO4, MgCl2, and MgSO4 in root dry weight. Total chlorophyll and nitrate contents of plants decreased with increasing salt doses, and the lowest value was obtained for NaCl application. Proline contents of plants were increased with increasing salt doses, and the highest value was obtained with the NaCl application. The effects of salt concentrations in nitrogen (N), potassium (K), and phosphorus (P) content of plants were significant. The presence of salt in the growth medium induced an important decrease the macro nutrient of the root and shoot part of plant such as N, P, K, calcium (Ca), and magnesium (Mg) content, but the N and P content of root and shoot part of the plant were increased with increasing of the HG application doses. The highest N and P increases were obtained with the 1.0 HG application for all salt types for both the root and shoots of plants. The HG added to saline soil significantly improved the variables affected by high salinity and also increased plant N and P, reduced soil electricity conductivity, nitrate, proline, and electrolyte leakage of plants, enhanced plant root and shoot dry weight by allowing nutrients and water to release to the plant as needed. The results suggested that HG has great potential for use in alleviating salinity stress on plant growth and growth parameters in saline soils of arid and semi-arid areas. This HG appears to be highly effective for use as a soil conditioner in vegetable growing, to improve crop tolerance and growth in saline conditions. It is intended to confirm the results of these studies by field trials.  相似文献   

13.
Salt stress can affect alfalfa growth directly by adversely affecting metabolism, or indirectly by its effect on Rhizobium capacity for symbiotic N2 fixation. Growth and carbohydrate metabolism in leaves, roots and nodules of two alfalfa cultivars (Medicago sativa cv Apica and salt-tolerant cv Halo) in association with two rhizobial strains (A2 and salt-tolerant Rm1521) exposed to different levels of NaCl (0, 20, 40, 80 or 160 mM NaCl) were assessed under controlled conditions. For both cultivars, shoot and root biomasses and shoot to root ratio significantly declined with increasing NaCl concentrations. Under 80 mM NaCl, Halo plants yielded 20% more fresh shoot biomass than Apica while plants inoculated with Rm1521 allocated more biomass to the roots than to the shoots compared to A2. Halo plants maintained a steady shoot water content (about 80%) under the entire range of NaCl concentrations. Shoot water content was more variable in Apica. Apica in association with salt-tolerant strain Rm1521 maintained a better water status than with strain A2, as indicated by the higher shoot water content at 80 mM NaCl. Under salt stress, two major compatible sugars involved in plant osmoregulation, sucrose and pinitol, increased in leaves while a large accumulation of starch was observed in roots. In nodules, pinitol, sucrose and starch increased under salt stress and were much more abundant with strain Rm1521 than with A2. This suggests that there could be an active transport from the shoot to the nodules to help maintain nodule activity under NaCl stress and that strain Rm1521 increases the sink strength toward nodules. Our results show that combining cultivars and rhizobial strains with superior salt tolerance is an effective strategy to improve alfalfa productivity in salinity affected areas.  相似文献   

14.
□ Growth and nutrient acquisition of tomato (Lycopersicon esculentum L.) cv ‘Amani’ were studied under induced salt stress in Hoagland's solution. The plants were treated for 37 days with salinity induced by incorporating different concentrations [0.0 (control), 50, 100, 150, or 200 mM] of sodium chloride (NaCl) to the nutrient solution. Slight reduction was obtained in growth represented by (shoot length and number, leaf number, and dry weight) when seedlings were directly exposed to NaCl stress from 0.0 to 100 mM. At higher concentrations (150 or 200 mM), growth parameters were adversely affected and seedlings died thereafter. Elevated salinity significantly reduced crude protein and fiber in shoots and roots. Tomato shoot and root contents of potassium (K), iron (Fe), and ash were reduced significantly in response to increased levels of salinity. Tissue contents of sodium (Na) and chloride (Cl) increased with elevated salinity treatments.  相似文献   

15.
The effect of increasing aluminum (Al) concentrations on root nutrient contents along with the concurrent translocation to the shoot of C4 plants prompted this study. Two‐week‐old maize (Zea mays cv XL‐72.3) plants were therefore submitted for 20 days to Al concentrations ranging from 0 to 3.00 mM in a medium with low ionic strength were used as a test system. Aluminum concentrations in root tissues showed a 3‐fold increase between 0 and 3.00 mM Al treatment, and was not detected in the shoot. Root plasma membrane‐H+ ATPase activity decreased after the 0.33 mg L‐1 Al treatment, while membrane permeability increased up to 1.00 mM Al treatment. Root and shoot biomass decreased after the 0.33 mM Al treatment. All elements in the roots, except potassium (K), manganese (Mn), and zinc (Zn) were highest for plants treated with 0.33 mM Al. Potassium increased continuously between 0 and 3.00 mM Al treatments, and iron (Fe) decreased above 0.33 mM. Only a slight decrease in nitrogen (N) was observed. All the measured nutrients in shoots, except N, Mn, and Fe decreased above 0.33 mM, but calcium (Ca) and magnesium (Mg) had little variation as Al varied. Data indicated that maximum net uptake for mineral nutrients, except Mn, occurred up to 0.33 mM Al. Translocation of phosphorus (P), K, Mn, and Zn decreased above 0.33 mM Al, N, and Ca decreased when any Al was added, and no clear trend was observed for Mg and Fe. Between the 0 and the 3.00 mM Al treatments, electrolytic conductance did not increased significantly indicating that the observed inhibitions of translocation from roots to shoots were not directly related to increasing membrane degradation.  相似文献   

16.
Abstract

Magnesium (Mg) deficiency is one of the major nutritional problems in tropic and subtropic areas, where the most soils are acidic. In this study, the effects of Mg application and Bradyrhizobium inoculation on growth, nodulation, symbiotic nitrogen (N) fixation as well as N nutrition status in soybean (Glycine max L.) were investigated in hydroponics under greenhouse conditions. With the increase of Mg up to 0.75?mM at low N and up to 0.5?mM at high N solutions, the dry weights of shoots, roots, and pod grain yield in soybean were increased, while further increase in Mg supply inhibited soybean growth. The availability of Mg was found to entail an improved uptake of N by plants and nodulation process in the root by Bradyrhizobium. Inoculation with rhizobial inoculants not only formed many nodules, but also increased soybean shoot, root biomass and yield, as well as plant N nutrient status.  相似文献   

17.
Abstract

Salinity is one of the serious abiotic stresses that has adverse effects on plant growth. The aim of this study was to investigate the effect of sodium chloride (NaCl) on germination and growth parameters of tomato plant as well as the role of Ca2+as an ameliorating agent. 100?mM NaCl and two concentrations of calcium (5 and 10?mM) were applied to tomato seeds and seedlings. This study was carried out in a Completely Randomized Design (CRD) with a total of six treatments each comprising of three replicates. The application of 100?mM of NaCl delayed the germination time by 27.6%, reduced the seedling length and seedling vigor by 24.33% and germination stress tolerance by 27.6% as compared to control. Salinity also reduced the plant growth (root and shoot length, root fresh and dry weight, shoot fresh and dry weight, membrane stability, relative water content and leaf area), whereas the application of calcium mitigated the negative effects of salinity on germination and growth to a greater extent. With increased calcium concentration, growth and germination increased significantly both alone and in the salt-affected plant. 10?mM calcium showed best results and enhanced the promptness index by 20.7%, seedling length and vigor by 15.1% and GSI by 20.7%. It also improved root fresh and dry weight, shoot fresh and dry weight, relative water content and leaf area. Similarly, 5?mM calcium also increased plant height and membrane stability index. The present study suggests that application of Ca2+ enhanced the growth of tomato plant under saline conditions.  相似文献   

18.
The present study was conducted to evaluate shoot and root mineral composition of salt-stressed Selva strawberry under application timing of salicylic acid (SA). Treatments included plants sprayed with 0.5 or 1 mM SA, plants exposed to 40 mM sodium chloride (NaCl), and plants sprayed with 0.5 or 1 mM SA 1 week before, simultaneously, or after initiation of 40 mM salinity. Results indicated that under saline conditions, sodium (Na) and chloride (Cl) contents increased along with decrease in nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), and zinc (Zn) in shoot and root of plants. In plants treated with SA at 1 mM concentration, 1 week before salinity application, root Mg and shoot Ca were greater in comparison to salt-stressed plants treated with the same SA concentration 1 week after their exposure to salt stress. Thus, earlier SA application appears to be a better strategy for optimized protection against deleterious influence of salinity.  相似文献   

19.
ABSTRACT

The present work was aimed at determining the limits of tolerance to sodium chloride (NaCl) of a halophyte, Beta macrocarpa Guss (wild Swiss chard). Five week-old plants were cultivated with a nutritive solution to which was added 0, 100, 200, and 300 mM NaCl. Plants were harvested after four weeks of treatment. The growth (fresh and dry weight, leaf surface area, and leaf number), water contents, and the mineral composition (meq · g?1 DW) of roots and leaves (reduced nitrogen (N), K+, Ca2 +, Na+, Cl?) were determined on individual plants. Results show that Beta macrocarpa can tolerate up to 200 mM NaCl. A significant decrease in biomass production (to 50% of control) was observed only for 300 mM NaCl. In the latter treatment, leaf mean surface area was 25% of control. The shoot-to-root ratio was not changed. Leaf hydration was not modified by salt treatment. This ability of the plant to maintain the hydric equilibrium of its leaves seemed associated with an efficient intracellular compartmentalization of Na+ and Cl? ions. Salt treatment had little effect on N content (80% of control), but decreased significantly K+ and Ca2 + contents. These three essential elements could be limiting for growth of leaves and roots of plants challenged by NaCl.  相似文献   

20.
Effects of NaCl on the seed germination and growth of Elaeagnus macrophylla seedlings and multiplication of Frankia Ema1 strain isolated from the root nodules of E. macrophylla were examined. The germination rate of seeds was not reduced by N aCI at 50 mM, but was reduced with further increase of the concentration, and germination did not occur at 200 mM NaCl. Root nodules were formed in the seedlings treated with 100 mM NaCl. The fresh and dry weight of the seedlings slightly decreased by the increase of the concentration of NaCl and the rate of decrease was 10–20% at NaCl concentrations higher than 100 mM. However, Na+ concentrations in the shoot increased up to 300 mM by treatment with N aCI at a concentration above 50 mM for 30 d and in some plants the lower leaves fell. The growth of free-living Frankia was markedly suppressed and the hyphae became thick and short in the solution at 100 mM NaCl. This trend was more obvious at 200 mM NaCl. Na+ concentration in the cells in the medium with 200 mM NaCl was lower than 20 mM and the cells underwent multiplication again when they were transferred to the medium which did not contain N aCl. These results indicate that the salt tolerance of E. macrophylla seedlings was not very high and the threshold for NaCl ranged between 50 and 100 mM, whereas Frankia Ema1 strain was able to survive in a much higher salt environment.  相似文献   

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