Responses of Batis maritima plants challenged with up to two‐fold seawater NaCl salinity

Batis maritima is a promising halophyte for sand‐dune stabilization and saline‐soil reclamation. This species has also applications in herbal medicine and as an oilseed crop. Here, we address the plant response to salinity reaching up to two‐fold seawater concentration (0–1000 mM NaCl), with a particular emphasis on growth, water status, mineral nutrition, proline content, and photosystem II integrity. Plant biomass production was maximal at 200 mM NaCl, and the plants survived even when challenged with 1000 mM NaCl. Plant water status was not impaired by the high accumulation of sodium in shoots, suggesting that Na⁺ compartmentalization efficiently took place in vacuoles. Concentrations of Mg²⁺ and K⁺ in shoots were markedly lower in salt‐treated plants, while that of Ca²⁺ was less affected. Soluble‐sugar and chlorophyll concentrations were hardly affected by salinity, whereas proline concentration increased significantly in shoots of salt‐treated plants. Maximum quantum efficiency (F_v/F_m), quantum yield of PSII (Φ_PSII), and electron‐transport rate (ETR) were maximal at 200–300 mM NaCl. Both nonphotochemical quenching (NPQ) and photochemical quenching (qP) were salt‐independent. Interestingly, transferring the plants previously challenged with supraoptimal salinities (400–1000 mM NaCl) to the optimal salinity (200 mM NaCl) substantially restored their growth activity. Altogether, our results indicate that B. maritima is an obligate halophyte, requiring high salt concentrations for optimal growth, and surviving long‐term extreme salinity. Such a performance could be ascribed to the plant capability to use sodium for osmotic adjustment, selective absorption of K⁺ over Na⁺ in concomitance with the stability of PSII functioning, and the absence of photosynthetic pigment degradation.     

Effects of sodium chloride treatments on growth and ion accumulation of the halophyte Haloxylon recurvum

Abstract

Effects of increasing salt concentrations 0, 180, 360 mol im³ sodium chloride (NaCl), on growth, succulence, mineral composition, and glycinebetaine content in Haloxylon recurvum was investigated. Fresh and dry weight of plants increased with an increase in salinity. Succulence of shoots increased at low salinity and decreased at high salinity. Root and shoot Ca⁺, Mg⁺, and K⁺content decreased with increasing salinity while both Na⁺ and Cl^‐ content increased, reaching 4,900 and 5,300 mmol kg^‐1 dry weight, respectively. Glycinebetaine (mol m^‐3 tissue water) significantly increased in shoots at 360 mol m^‐3 NaCl, but did not differ significantly in roots treated with from 0 to 360 mol m^‐3 NaCl. Haloxylon recurvum is a highly salt tolerant stem succulent plant which accumulate a high quantity of salt, which makes it a good candidate to use for phytoremediation in highly saline areas of the sub‐tropics.     

Salt Stimulation and Tolerance in an Intertidal Stem-Succulent Halophyte

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.     

Differential responses of three chamomile genotypes to salinity stress with respect to physiological,morphological, and phytochemical characteristics

Effect of water salinity was studied in different Matricaria recutita L. genotypes (Isfahan, Ahvaz, and Shiraz) to understand their protective mechanisms and agronomic performance. Based on a split-plot design arranged in a randomized complete-block consisted of four salinity levels as the main plot and three genotypes as the subplots with three replications this field experiment was conducted in 36 plots with 3 m² space in the Isfahan Center for Research of Agricultural Science and Natural Resources during 2014–2015. The findings showed that the three genotypes differed in resistance to salinity and tolerance mechanisms. They have evolved different physiological, morphological, and biochemical adaptations to salt stress. The Ahvaz genotype in the absence of salt, the Isfahan genotype at 6, and the Shiraz genotype at 9 and 12 dS m^?1 sodium chloride (NaCl) were desirable, taking both quantity and quality into consideration. While preserving shoot growth, the Isfahan genotype was more tolerant to 6 dS m^?1 NaCl most likely due to peroxidase activity. The resistance of the Shiraz genotype is associated with root growth stimulation at 9 and Na compartmentation in root at 12 dS m^?1 NaCl. The Isfahan genotype had the highest oil and chamazulene content, which was not affected by salinity. The Shiraz genotype in the control treatment, the Isfahan genotype at 6 and 9 and the Ahavaz genotype at 12 dS m^?1 NaCl synthesized higher flavonoid compounds.     

CONTRIBUTION OF PROLINE AND INORGANIC SOLUTES TO OSMOTIC ADJUSTMENT IN COTTON UNDER SALT STRESS

Physiological responses to salt stress were investigated in two cotton (Gossypium hirsutum L.) cultivars (Pora and Guazuncho) grown hydroponically under various concentrations of NaCl. Dry matter partitioning, plant water relations, mineral composition and proline content were studied. Proline and inorganic solutes were measured to determine their relative contribution to osmotic adjustment. Both leaf water potential (Ψ_w) and osmotic potential (Ψ_s)decreased in response to NaCl levels. Although Ψ_wand Ψ_s decreased during salt stress, pressure potential Ψ_p remained between 0.5 to 0.7 MPa in control and all NaCl treatments, even under 200 mol m^?3 NaCl. Increased NaCl levels resulted in a significant decrease in root, shoot and leaf growth biomass. Root / shoot ratio increased in response to salt stress. The responses of both cultivars to NaCl stress were similar. Increasing salinity levels increased plant Na⁺ and Cl^?. Potassium level remained stable in the leaves and decreased in the roots with increasing salinity. Salinity decreased Ca²⁺ and Mg²⁺ concentrations in leaves but did not affect the root levels of these nutrients. The K/Na selectivity ratio was much greater in the saline treated plants than in the control plants. Osmotic adjustment of roots and leaves was predominantly due to Na⁺ and Cl^? accumulation; the contribution of proline to the osmotic adjustment seemed to be less important in these cotton cultivars.     

Growth promotion by sodium in amaranthaceous plants

The amaranthaceous dwarf glasswort, Swiss chard, table beet, spinach and Mexican tea were grown in solutions containing 0, 20, 40, 80, 120, 160, 180 and 200 mol m^?3 sodium chloride (NaCl). Maximum growth and increase of biomass production compared to that at 0 mol m^?3 of dwarf glasswort was observed at 200 mol m^?3 (245%), and Swiss chard (146%), table beet (128%) and spinach (138%) at 80 mol m^?3. The growth of these species increased with increasing sodium (Na) concentration of shoot until it reached 4.18, 2.42, 1.60 and 1.58 mol kg^?1, respectively. These indicate that the order of Na-loving character is dwarf glasswort >> Swiss chard > table beet = spinach. The water contents increased with increasing Na concentration until growth reached maximum in dwarf glasswort and Swiss chard. In these highly Na-loving species, Na is activity transported to shoots and utilized for producing osmotic pressure to absorb water.     

EFFECT OF MIXED-SALT SALINITY ON GROWTH AND ION RELATIONS OF A QUINOA AND A WHEAT VARIETY

ABSTRACT

Salinity is among the most widespread and prevalent problems in irrigated agriculture. Many members of the family Chenopodiaceae are classified as salt tolerant. One member of this family, which is of increasing interest, is quinoa (Chenopodium quinoa Willd.) which is able to grow on poorer soils. Salinity sensitivity studies of quinoa were conducted in the greenhouse on the cultivar, “Andean Hybrid” to determine if quinoa had useful mechanisms for salt tolerant studies. For salt treatment we used a salinity composition that would occur in a typical soil in the San Joaquin Valley of California using drainage waters for irrigation. Salinity treatments (EC_i ) ranging from 3, 7, 11, to 19?dS?m^?1 were achieved by adding MgSO₄, Na₂SO₄, NaCl, and CaCl₂ to the base nutrient solution. These salts were added incrementally over a four-day period to avoid osmotic shock to the seedlings. The base nutrient solution without added salt served as the non-saline control solution (3?dS?m^?1). Solution pH was uncontrolled and ranged from 7.7 to 8.0. For comparative purposes, we also examined Yecora Rojo, a semi-dwarf wheat, Triticum aestivum L. With respect to salinity effects on growth in quinoa, we found no significant reduction in plant height or fresh weight until the electrical conductivity exceeded 11?dS?m^?1. The growth was characteristic of a halophyte with a significant increase in leaf area at 11?dS?m^?1 as compared with 3?dS?m^?1 controls. As to wheat, plant fresh and dry weight, canopy height, and leaf area did not differ between controls (3?dS?m^?1) and plants grown at 7?dS?m^?1. Beyond this threshold, however, plant growth declined. While both quinoa and wheat exhibited increasing Na⁺ accumulation with increasing salinity levels, the percentage increase was greater in wheat. Examination of ion ratios indicated that K⁺:Na⁺ ratio decreased with increasing salinity in both species. The decrease was more dramatic in wheat. A similar observation was also made with respect to the Ca²⁺:Na⁺ ratios. However, a difference between the two species was found with respect to changes in the level of K⁺ in the plant. In quinoa, leaf K⁺ levels measured at 19?dS?m^?1 had decreased by only 7% compared with controls. Stem K⁺ levels were not significantly affected. In wheat, shoot K⁺ levels had decreased by almost 40% at 19?dS?m^?1. Correlated with these findings, we measured no change in the K⁺:Na⁺ selectivity with increasing salinity in quinoa leaves and only a small increase in stems. In wheat however, K⁺:Na⁺ selectivity at 3?dS?m^?1 was much higher than in quinoa and decreased significantly across the four salinity levels tested. A similar situation was also noted with Ca²⁺:Na⁺ selectivity. We concluded that the greater salt tolerance found in quinoa relative to wheat may be due to a variety of mechanisms.     

EFFECT OF SALINIZATION OF SOIL ON GROWTH,WATER STATUS AND NUTRIENT ACCUMULATION IN SEEDLINGS OF ACACIA AURICULIFORMIS (FABACEAE)

Greenhouse experiments were conducted to assess the effects of salinization of soil on emergence, growth, water status, proline content, and mineral accumulation of seedlings of Acacia auriculiformis A. Cunn. ex Benth. (Fabaceae). Sodium chloride (NaCl) was added to the soil and salinity was maintained at 0.3, 3.9, 6.0, 7.9, 10.0, 12.1, and 13.9 dS m^?1. Salinity caused reduction in water potential of tissues, which resulted in internal water deficit to plants. Consequently, seedling growth significantly decreased with increase in soil salinity. Proline content in tissues increased with increase in salinity. Potassium and sodium content significantly increased in tissues as salinity increased. Nitrogen content significantly increased in tissues with salinization of soil. Phosphorus, calcium and magnesium content significantly decreased as salinity increased. Changes in tissues and whole-plant accumulation patterns of other nutrients, as well as possible mechanisms for avoidance of sodium toxicity in this tree species in response to salinity, are discussed.     

Effects of Nutrient and NaCl Salinity on Growth,Yield, Quality and Composition of Pepper Grown in Soilless Closed System

The effects of nutrient or sodium chloride (NaCl) salinity on pepper grown in closed soilless culture systems were studied. A control (2 dS m^?1) and two saline nutrient solutions (4 dS m^?1) differing in the salt sources (fertilizers or NaCl) were studied. Shoot biomass production as well as total and marketable yield were more affected by NaCl than nutrient salinity. Fruit dry matter and total soluble solids increased in both salinity treatments compared to the control. Total phenol content rose slightly (10%) with NaCl salinity, while the concentration of carotenoids was enhanced by 40% with NaCl compared to the control and nutrient salinity. The results showed that the response of pepper to salinity is both osmotic and ion specific, but a more negative effect was recorded under NaCl stress. Moreover, the highest content of antioxidant compounds in NaCl treated fruits may indicate that NaCl caused more stressful conditions than nutrient salinity.     

COMPARISON OF OSMOTIC REGULATION IN DEHYDRATION- AND SALINITY-STRESSED SUNFLOWER SEEDLINGS

Plant dry matter accumulation rate (DMAR), relative water content (RWC), electrolyte leakage percentage (ELP), chlorophyll content, osmotic adjustment ability (OAA), and osmotica accumulation in leaves of sunflower (Helianthus annuus L.) seedlings under different levels of dehydration and salinity stress induced by iso-osmotic PEG (polyethylene glycol) or sodium chloride (NaCl) were evaluated. Plants were subjected to four stress treatments for 10 days: ?0.44 MPa PEG6000, ?0.44 MPa NaCl, ?0.88 MPa PEG6000, ?0.88 MPa NaCl. Results showed that PEG and NaCl treatments decreased the plant's DMAR and RWC, and NaCl treatments had more severe inhibitory effect on the plants than PEG treatments. Leaf ELP in sunflower seedlings increased after NaCl and PEG treatments. However, leaf ELP under salt stress was higher than that under dehydration stress (PEG treatment). All stress treatments increased OAA in plant leaves. Leaf OAA was enhanced significantly as PEG concentration increases, while leaf OAA was less enhanced at higher concentration of NaCl. OAA of sunflower leaves under dehydration stress was due to an increase in potassium (K⁺), calcium (Ca²⁺), amino acid, organic acid, magnesium (Mg²⁺), and proline content. OAA of sunflower leaves under moderate salt stress was owing to an increase in K⁺, chlorine (Cl^?), amino acid, organic acid, sodium (Na⁺), and proline content, and was mainly due to an accumulation of K⁺, Cl^?, Na⁺, and proline under severe salt stress.     

Effect of potassium on growth,water relations,and the inorganic and organic solute contents for two maize cultivars grown under saline conditions

Two cultivars ("Spirit”; and “Jubileo") of maize (Zea mays L.) were studied to compare their response to various levels of potassium (K⁺) (0.1, 1, and 6 mol/m³) and sodium chloride (NaCl) (0 and 50 mol/m³) in nutrient solutions with 16 h photoperiod, day/night temperature regime of 25/20°C, and a photon flux density of 380 nmol/m²/sec. ‘Spirit’ produced about 1.5 times more biomass than ‘Jubileo’ at 6 mol/m³ K⁺in the control treament, while at 0.1 mol/m³ K⁺ the growth of both cultivars was similar. Plant fresh weight was reduced by 20% in ‘Spirit’ and by 30% in ‘Jubileo’ with 50 mol/m³ NaCl and 6 mol/m³ K⁺. Growth reduction of maize plants by salinity was associated with an excessive accumulation of sodium (Na⁺) and chloride (Cl^‐) rather than an effect on water relations. The higher salt tolerance of ‘Spirit’ can be related to its greater capacity to exclude Na⁺ and Cl^‐ from the leaves and to maintain a higher K⁺/Na⁺ ratio. Increasing the K⁺ supply in the rooting media did not improve growth reduction imposed by the 50 mol/m³ NaCl treatment. ‘Jubileo’ had a lower turgor potential than ‘Spirit’. High concentrations of Na⁺ in the leaves may help to maintain turgor, but cannot substitute for K⁺ to give adequate growth of maize. The accumulation in leaf tissue of inorganic ions was sufficient for osmotic adjustment in both cultivars and no single organic solute appears to be important in this process.     

Different Levels of Irrigation Water Salinity and Biochar Influence on Faba Bean Yield,Water Productivity,and Ions Uptake

Greenhouse experiment was conducted to investigate the effect of different levels of irrigation water salinity (0.5, 2.5, 5 and 7.5 dS m^?1) and wheat straw biochar (0%, 1.25%, 2.5%, and 3.75% w/w) on growth and yield of faba been using complete randomized design with three replications. Stomatal conductance (green canopy temperature) of faba bean increased (decreased) by application of biochar at each salinity level. The results showed increasing salinity to 2.5 dS m^?1 at zero biochar application increased the seed yield through osmotic adjustment, while by declining the osmotic potential, the nutritional values of biochar caused the seed yield to increase by increasing salinity to 5 dS m^?1. The root length density and root dry weight density in 0–8 cm soil layer declined under application of 3.75% w/w biochar in all salinity levels in comparison with that obtained in 2.5% w/w biochar, due to higher saline condition of the soil as result of higher biochar application. The results showed that addition of 2.5% w/w biochar can significantly mitigate salinity stress due to its high salt sorption capacity and by increasing potassium/sodium ratio in the soil. In general, since 2.5 % w/w biochar and salinity of 5 dS m^?1 increased dry seed yield and irrigation water productivity compared with that obtained in control (B₀S_0.5), these levels are recommended to improve faba bean growth and yield; however, these levels have to be evaluated under field conditions.     

Growth,Water Status,and Nutrient Accumulation of Seedlings of Tamarindus indica Linn. in Response to Soil Salinity

Greenhouse experiments in a completely randomized block design were conducted to assess the effect of soil salinity on emergence, growth, water status, proline content, and mineral accumulation of seedlings of Tamarindus indica Linn. (Caesalpiniaceae). Sodium chloride (NaCl) was added to the soil, and the salinity was maintained at 0.2, 3.9, 6.2, 8.1, 10.0, 11.9, and 13.9 dS m^?1. Salinity lowered water content and water potential of tissues, which resulted in an internal water deficit to plants. Consequently, seedling growth significantly decreased and proline content in tissues increased as salinity increased. There were no effective mechanisms to control net uptake of sodium (Na⁺) and its transport to shoot. Potassium (K) and calcium (Ca) contents in tissues significantly decreased, while nitrogen (N) content significantly increased as salinity increased. Changes in tissues and whole-plant accumulation patterns of other nutrients, as well as possible mechanisms for avoidance of Na⁺ toxicity in this species in response to salinity, are discussed.     

Function of sodium and potassium in growth of sodium-loving Amaranthaceae species

We observed that the growth of three Amaranthaceae species was promoted by sodium (Na), in the order dwarf glasswort (Salicornia bigelovii Torr.) >> Swiss chard (Beta Burgaris L. spp. cicla cv. Seiyou Shirokuki) > table beet (Beta vulgaris L. spp. vulgaris cv. Detroit Dark Red). In the present study, these Na-loving plants were grown in solutions containing 4 mol m^?3 nitrate nitrogen (NO₃-N) and 100 mol m^?3 sodium chloride (NaCl) and potassium chloride (KCl) under six Na to potassium (K) ratios, 0:100, 20:80, 40:60, 60:40, 80:20 and 100:0, to elucidate the function of Na and K on specific characteristics of Na-loving plants. The growth of dwarf glasswort increased with increasing Na concentration of the shoot, and the shoot dry weight of plants grown in 100:0 Na:K was 214% that of plants grown at 0:100. In Swiss chard and table beet, growth was unchanged by the external ratio of Na to K. The water content was not changed in Swiss chard or table beet by the external Na to K ratio. These observations indicate that both Na and K have a function in osmotic regulation. However, dwarf glasswort could not maintain succulence at 0:100; therefore, Na has a specific function in dwarf glasswort for osmotic regulation to maintain a favorable water status, and the contribution of K to osmotic regulation is low. NO₃-N uptake was promoted by Na uptake in dwarf glasswort and Swiss chard. NO₃-N uptake and transport to shoots was optimal at 100:0 in dwarf glasswort and at 80:20 in Swiss chard. These functions are very important for the Na-loving mechanism, and the contribution of K was lower in dwarf glasswort than in Swiss chard.     

Improvement in the Adaptation of Lygeum Spartum L. to Salinity In the Presence of Calcium

Lygeum spartum L. has been recently introduced in areas where salinity is high in soils. However, there are no studies about the physiological response of these plants to salt excess. The effect of sodium chloride (NaCl) on plant growth and water status was studied. Also, the effect of calcium (Ca) addition to salinity conditions was analyzed because of the coexistence of salinity and calcareous soils. Dry weight (DW), transpiration, and osmotic potential (Ψπ) decreased with elevated NaCl and were restored with Ca²⁺, whereas moderate salinity had no effect. Fresh weight (FW), water potential (Ψω), and root hydraulic conductance (L ₀) decreased with salinity; Ca²⁺ supply had an ameliorative effect at moderate salinity. Sodium (Na⁺) increased in leaf sap at high levels of NaCl and was decreased by Ca²⁺. Lygeum spartum showed a resistance to moderate salinity, but the effect of Ca²⁺ depends on salinity intensity. Thus, the role of Ca²⁺ in the tolerance to salinity was emphasized.     

Soil salt and NaCl have different effects on seed germination of the halophyte Suaeda salsa

Seed germination is a key life‐history stage of halophytes. Most studies on seed germination of halophytes have focused on the effects of a single salt, while little information is available on the effects of mixed salt in the natural habitat. Due to the contribution of multiple ions in saline soil, we hypothesized that the effect of mixed salt on seed germination will differ from that of a single salt and the mechanism of how germination is affected will differ as well. The effects of mixed salt and NaCl on germination, water imbibition, and ionic concentrations of seeds of Suaeda salsa (L.) Pall. were compared at various salinity levels. Germination percentage (GP) and rate (GR) decreased with increasing salinity level, regardless of salt type. There was no difference in GP or GR between mixed salt and NaCl when the salinity level was below 20 dS m^?1. Above 20 dS m^?1, GP and GR in NaCl were lower than those in mixed salt. At the same salinity level, Na⁺ concentration in seeds was higher in NaCl than that in mixed salt, but the reverse was true for Ca²⁺ and Mg²⁺ concentrations. Imbibition rate for seeds in NaCl was lower than that in mixed salt at the same salinity level. Addition of Ca²⁺ and Mg²⁺ alleviated the inhibition of NaCl on seed germination. In conclusion, our results suggest that the effects of soil salts and NaCl on seed germination are different, and using NaCl instead of soil salt might not be realistic to show the effect of saline stress on seed germination of halophytes in the natural habitat.     

Different Eucalyptus Species Show Different Mechanisms of Tolerance to Salinity and Salinity × Hypoxia

ABSTRACT

We studied the effect of sodium chloride (NaCl) salinity and oxygen deficiency stress on growth and leaf ionic composition of three Eucalyptus species [E. tereticornis, E. camaldulensis (Silverton), and E. camaldulensis (Local)]. Species were grown with control (no NaCl) and salinity (150 mol m^?3 NaCl) under hypoxic and non-hypoxic conditions in nutrient solution with five replications following CRD. Species differed significantly in their response to salinity and hypoxia. Absolute shoot dry matter was significantly better in E. camaldulensis (Silverton) in salinity and in E. camaldulensis (Local) in saline hypoxic treatment. E. tereticornis was the most sensitive species to salinity and salinity × hypoxia in the root environment. Sodium (Na⁺) and chloride (Cl^?) concentrations were significantly lower in E. camaldulensis (Local) in non-hypoxic saline treatment compared to the other two species. E. camaldulensis (Silverton) seems to have better tissue compartmentalization, whereas E. camaldulensis (local) seems to have better exclusion of Na⁺ at the root level.     

Effects of NaCl salinity on miniature dwarf tomato ‘Micro‐Tom’: II. Shoot and root growth responses,fruit production,and osmotic adjustment 1

The growth and production of miniature dwarf tomato selection Lycopersicon esculentum ’Micro‐Tom’ plants grown from seedling to harvest in solution batph culture’ at four different NaCl salinity levels (2.4 [control, no NaCl], 7.6, 12.8, or 18 dS‐m^‐1 solution conductivities) was monitored. Incremental reductions in canopy extent and shoot area of ‘Micro‐Tom’ were observed with increasing solution NaCl level. Root growth and shoot height were somewhat less responsive to imposed salinity. Fruit number, fruit size, and leaf tissue osmotic potential decreased as NaCl concentration increased. Fruit yield was highly correlated with total canopy and shoot area, but not with tissue osmotic or total water potential. ‘Micro‐Tom’ plants survived and continued fruit production at higher salinity levels despite reduced canopy growth. Treatment effects on vegetative growth and fruit production became more pronounced later in the growth cycle.     

Effect of salinity and arbuscular mycorrhizal fungi on growth and some physiological parameters of Citrus jambheri

Arbuscular mycorrhizal (AM) fungi alleviate the unfavorable effects of salinity stress on plant growth. A pot study was conducted to determine the effects of AM fungi and salt on growth and some physiological parameters of Citrus jambheri rootstock. Four levels of salinity (2, 4, 6, and 8 dS m^?1 as NaCl) and three mycorrhizal treatments (Glomus etunicatum, Glomus intraradices and non-mycorrhizal (NM) control) were used. As salinity increased, all measured characteristics of plants after 4.5-month growth except Na uptake, proline content, and electrolyte leakage decreased. Shoot dry weight and K uptake were significantly higher in G. intraradices-colonized seedlings than NM controls at all salinity levels. Root dry weight and shoot P uptake were significantly higher in G. etunicatum-colonized seedlings than NM controls at all salinity levels. G. intraradices-colonized seedlings had significantly higher proline content than NM controls and G. etunicatum-colonized seedlings at salinity levels of 4, 6 and 8 dS m^?1. The electrolyte leakage percentage was significantly lower in G. intraradices-colonized seedlings than NM controls at all salinity levels. The data demonstrated that mycorrhizal citrus seedlings exhibited greater tolerance to salt stress than NM seedlings and the enhanced proline content seems to be one of the mechanisms involved.