Effects of Calcium Chloride on Growth,Membrane Permeability and Root Hydraulic Conductivity in Two Atriplex Species Grown at High (Sodium Chloride) Salinity

Calcium (Ca) has an important role in plant physiology, including involvement in the responses to salt stress, and controls numerous processes. To overcome the negative impact of high salinity, the addition of supplemental Ca to the growth medium as an ameliorative agent could be necessary. Atriplex halimus subsp. schweinfurthii and Atriplex canescens subsp. linearis were grown in hydroponic conditions to investigate the effectiveness of supplementary calcium chloride (CaCl₂) applied into nutrient solution on plants grown at high (400 mM) sodium chloride (NaCl) concentration. Treatments were: 1) nutrient solution alone [control (C)]; 2) nutrient solution plus 400 mM sodium chloride (NaCl); and 3) nutrient solution and 400 mM NaCl plus supplementary 40 mM CaCl₂ supplied in nutrient solution (NaCl + CaCl₂). The experiment was set up as a completely randomized design, consisting of two species (A. halimus and A. canescens), three treatments (control, NaCl, and NaCl + CaCl₂), and five replicates. Dry weight and chlorophyll content of plants grown at high NaCl were lower than those at normal nutrient solution. Supplementary CaCl₂ ameliorated the negative effects of salinity on plant growth in both species. Root hydraulic conductivity (L ₀) decreased with elevated NaCl and increased with supplementary CaCl₂ compared to the stressed plants. Membrane permeability increased with high NaCl application and these increases in root membrane permeability decreased with supplementary CaCl₂ compared to the NaCl treatment. Sodium (Na) concentration in plant tissues increased in both species in high NaCl level. Application of supplementary CaCl₂ lowered Na concentration. Concentrations of calcium (Ca) and potassium (K) were at deficient ranges in the plants grown at high NaCl levels and these deficiencies were corrected by supplementary CaCl₂.     

SOME DELETERIOUS EFFECTS OF LONG-TERM SALT STRESS ON GROWTH,NUTRITION, AND PHYSIOLOGY OF GERBERA (GERBERA JAMESONII L.) AND POTENTIAL INDICATORS OF ITS SALT TOLERANCE

Tolerance of gerbera (Gerbera jamesonii L.) to long-term sodium chloride (NaCl) salt stress was evaluated by subjecting plants to 0, 10, 20, 30 and 40 mM NaCl levels for ten weeks. Increased NaCl led to a significant decrease in leaf and stem biomass. Salt stress significantly affected sodium (Na⁺), potassium (K⁺) concentrations in leaves, stems and roots leading to sharp declines in K⁺/Na⁺ ratios. Magnesium concentrations in stems and roots also showed significant declines. Adverse effect of salt stress on chlorophyll content was also significant. Proline seemed less effective in osmotic adjustment under long-term high salt stress. Switching from vegetative to reproductive growth phase was crucial for certain physiological functions. Leaf Na⁺ concentration showed significant correlation with important traits. These data suggest that NaCl threshold level in irrigation water for gerbera is around 10 mM. Leaf fresh weight, chlorophyll content and leaf K⁺/Na⁺ ratio are promising indicators of salt-sensitivity of gerbera.     

Kinetics of Zinc Uptake and Anatomy of Roots and Leaves of Coffee Trees as Affected by Zinc Nutrition

Abstract

The influence of silicon (Si) (2.5 mM), sodium chloride (NaCl) (100 mM), and Si (2.5 mM) + NaCl (97.5 mM) supply on chlorophyll content, chlorophyll fluorescence, the concentration of malondialdehyde (MDA), H₂O₂ level, and activities of superoxide dismutase (SOD; E.C.1.15.1.1.), ascorbate peroxidase (APx; E.C.1.11.1.11.), catalase (CAT; E.C.1.11.1.6.), guaiacol peroxidase (G-POD; E.C.1.11.1.7.) enzymes, and protein content were studied in tomato (Lycopersicon esculentum Mill c.v.) leaves over 10-day and 27-day periods. The results indicated that silicon partially offset the negative impacts of NaCl stress with increased the tolerance of tomato plants to NaCl salinity by raising SOD and CAT activities, chlorophyll content, and photochemical efficiency of PSII. Salt stress decreased SOD and CAT activities and soluble protein content in the leaves. However, addition of silicon to the nutrient solution enhanced SOD and CAT activities and protein content in tomato leaves under salt stress. In contrast, salt stress slightly promoted APx activity and considerably increased H₂O₂ level and MDA concentration and Si addition slightly decreased APx activity and significantly reduced H₂O₂ level and MDA concentration in the leaves of salt-treated plants. G-POD activity was slightly decreased by addition of salt and Si. Enhanced activities of SOD and CAT by Si addition may protect the plant tissues from oxidative damage induced by salt, thus mitigating salt toxicity and improving the growth of tomato plants. These results confirm that the scavenging system forms the primary defense line in protecting oxidative damage under stress in crop plants.     

Physiological,nutritional and growth responses of melon (Cucumis melo L.) to a gradual salinity built-up in recirculating nutrient solution

Minimizing salinity impacts on yield in melon crops cultivated in closed-loop hydroponic systems requires better understanding of the physiological impact of gradual salt accumulation in the recycled solution. To attain this objective, different sodium chloride (NaCl) concentrations in the irrigation water, i.e. 0.7, 2.5, and 5 mM, were applied in two cropping seasons (winter-spring;WS and spring-summer;SS). In both seasons plant biomass and yield were negatively affected only in high NaCl-treated plants, due to stomatal limitations, which restricted carbon dioxide (CO₂) diffusion into the leaf, osmotic and salt-specific effects. However, a progressive NaCl built-up to maximum concentrations in the root zone solution of 15 (WS) and 20 mM (SS), enabled plants to preserve several physiological mechanisms, thereby adjusting growth and yield without impairing fruit quality. Our results suggest that the use of irrigation water, containing up to 2.5 mM NaCl, is feasible in melon crops grown in closed-loop hydroponic systems, without yield and quality losses.     

Ni Phytoaccumulation in Mentha aquatica L. and Mentha sylvestris L.

Water, Air, &; Soil Pollution - The ability of scented geraniums (Pelargonium sp. `Frensham’) to uptake cadmium and nickel was assessed undergreenhouse conditions. Plants were grown in an...     

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.     

Arbuscular mycorrhizal fungus and rhizobacteria affect the physiology and performance of Sulla coronaria plants subjected to salt stress by mitigation of ionic imbalance

Salt stress has become a major menace to plant growth and productivity. The main goal of this study was to investigate the effect of inoculation with the arbuscular mycorrhizal fungi (AMF; Rhizophagus intraradices) in combination or not with plant growth‐promoting rhizobacteria (PGPR; Pseudomonas sp. (Ps) and Bacillus subtilis) on the establishment and growth of Sulla coronaria plants under saline conditions. Pot experiments were conducted in a greenhouse and S. coronaria seedlings were stressed with NaCl (100 mM) for 4 weeks. Plant biomass, mineral nutrition of shoots and activities of rhizosphere soil enzymes were assessed. Salt stress significantly reduced plant growth while increasing sodium accumulation and electrolyte leakage from leaves. However, inoculation with AMF, whether alone or combined with the PGPR Pseudomonas sp. alleviated the salt‐induced reduction of dry weight. Inoculation with only AMF increased shoot nutrient concentrations resulting in higher K⁺: Na⁺, Ca²⁺: Na⁺, and Ca²⁺: Mg²⁺ ratios compared to the non‐inoculated plants under saline conditions. The co‐inoculation with AMF and Pseudomonas sp. under saline conditions lowered shoot sodium accumulation, electrolyte leakage and malondialdehyde (MDA) levels compared to non‐inoculated plants and plants inoculated only with AMF. The findings strongly suggest that inoculation with AMF alone or co‐inoculation with AMF and Pseudomonas sp. can alleviate salt stress of plants likely through mitigation of NaCl‐induced ionic imbalance, thereby improving the nutrient profile.     

Effects of foliar spray of two kinds of zinc oxide on the growth and ion concentration of sunflower cultivars under salt stress

This study investigated the effects of foliar application of normal and nano-sized zinc oxide on the response of sunflower cultivars to salinity. Treatments included five cultivars (‘Alstar’, ‘Olsion’, ‘Yourflor’, ‘Hysun36’ and ‘Hysun33’), two salinity levels [0 and 100 mM sodium chloride (NaCl)], and three levels of fertilizer application. Fertilizer treatments were the foliar application of normal and nano-sized zinc oxide (ZnO). Foliar application of ZnO in either forms increased leaf area, shoot dry weight, net carbon dioxide (CO₂) assimilation rate (A), sub-stomatal CO₂ concentration (Ci), chlorophyll content, Fv/Fm, and Zn content and decreased Na content in leaves. The extent of increase in chlorophyll content, Fv/Fm and shoot weight was greater as nano-sized ZnO was applied to the normal form. The results show that the nano-sized particles of ZnO compared to normal form has greater effect on biomass production of sunflower plants.     

The effect of N and NaCl on growth,yield, and nitrate content of salad rocket (Eruca sativa Mill.)

Hydroponic production of rocket as a salad vegetable has become increasingly important in recent years. Rocket is known to be a high nitrate (NO₃^–)-accumulating vegetable, which can be grown throughout the year. In the present study, rocket was grown in a floating hydroponic system at three levels of nitrogen (N) and sodium chloride (NaCl). The highest yield was obtained at 14 mM N, whereas the yield was lower at 20 mM and 40 Mm NaCl. Leaf elongation was more sensitive to salinity than leaf differentiation. Adding NaCl to the nutrient solution increased the relative chlorophyll content. Na⁺ and Cl^– concentrations increased as salinity increased. NO₃^? levels in fresh biomass increased with increased amounts of NO₃^? in the nutrient solution, and plants at 18 mM N were able to maintain a higher NO₃^? : Cl^? ratio than those at 10 mM N.     

Growth,Chlorophyll, and Cation Concentration of Tetraploid Wheat on a Solution High in Sodium Chloride Salt: Hulled Versus Free-Threshing Genotypes

Based on the literature, under-utilized hulled wheats could be tolerant to some harsh environmental conditions. The effect of salt stress on chlorophyll content, leaf area, dry weight, and ion concentrations in eight genotypes of tetraploid wheat (Triticum turgidum) using a three-replicate completely random design indoor experiment was studied. These genotypes included six hulled wheat (HW), T. turgidum subspp. Dicoccum, and two free-threshing wheat (FTW), T. turgidum subspp. durum. Salt stress was induced by adding sodium chloride (NaCl) to a hydroponic medium to 40, 80, and 120 mM, in addition to control. Salinity reduced leaf content of chlorophyll a (chl-a) at 120 mM but had not significant effect on chlorophyll b (chl-b) content. Salt stress decreased plant leaf area by nearly 63%. Plant top dry weight declined by 52% with increasing salinity to 120 mM level. Plant top calcium (Ca²⁺) content was not affected, whereas plant top sodium (Na⁺) concentration increased and potassium (K⁺) and magnesium (Mg⁺) concentration decreased with increasing salinity, averaged over genotypes. No significant interaction of genotype × salinity was detected for traits studied in this experiment. When contrasted as two groups of genotypes, i.e., HW vs. FTW, the former group suffered more severe decreases in terms of chl-a, chl-b, leaf area, dry weight, and Mg²⁺ concentration and a more pronounced increase in Na⁺ compared to the FTW. Overall, no evidence of salt tolerance was found for hulled tetraploid wheats of central Iran.     

Growth Responses and Nitrogen-15 Absorption of Desert Saltgrass Under Salt Stress

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.     

Improving salt stress responses of the symbiosis in alfalfa using salt-tolerant cultivar and rhizobial strain

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.     

Effects of foliar spray of nano-particles of FeSO4 on the growth and ion content of sunflower under saline condition

This study investigated the effects of foliar spray of normal and nano-particles of iron sulfate (FeSO₄) on the response of sunflower cultivars to salinity. Treatments included five cultivars (Alstar, Olsion, Yourflor, Hysun36 and Hysun33), two salinity levels (0 and 100 mM sodium chloride (NaCl)), and three levels of fertilizer application. Fertilizer treatments were the foliar application of normal and nano-particles of FeSO₄. Foliar application of FeSO₄ in either form increased leaf area, shoot dry weight, net carbon dioxide (CO₂) assimilation rate (A), sub-stomatal CO₂ concentration (Ci), chlorophyll content, Fv/Fm and iron (Fe) content and decreased sodium (Na) content in leaves. The extent of increase in chlorophyll a content by foliar spray of FeSO₄ nano-particles was significantly greater than normal form. The results showed that the FeSO₄ nano-particles increased biomass production of sunflower plants greater in comparison with normal form, although no significant difference was found between two forms.     

EFFECTS OF PLANT GROWTH PROMOTING BACTERIA ON YIELD,GROWTH, LEAF WATER CONTENT,MEMBRANE PERMEABILITY,AND IONIC COMPOSITION OF STRAWBERRY UNDER SALINE CONDITIONS

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.     

RESPONSES OF SOME ENZYMES AND KEY GROWTH PARAMETERS OF SALT-STRESSED MAIZE PLANTS TO FOLIAR AND SEED APPLICATIONS OF KINETIN AND INDOLE ACETIC ACID

The study examined the effects of kinetin (KIN) and indoleacetic acid (IAA) applied as seed treatment or sprayed on leaves of salinity stressed plants. Five -week old maize (Zea mays L. cv. ‘DK 647 F1’) plants were grown in pots containing peat and perlite in 1:1 (v/v) mixture. Different treatments used were: 1) control (nutrient solution alone), 2) salt stress [100 mM sodium chloride (NaCl)], 3) 100 mM NaCl and 1 mM kinetin (KIN), 4) 100 mM NaCl and 2 mM KIN, 5) 100 mM NaCl and 1 mM indole acetic acid (IAA), 6) 100 mM NaCl and 2 mM IAA, 7) 100 mM NaCl and 25 mg L^?1 KIN and 8) 100 mM NaCl and 25 mg L^?1 IAA. In treatments 7 and 8 application was to the seeds, for treatments 3-6 it was applied to foliage. The seeds were soaked in KIN or IAA solution for 12 h. Salt stress reduced the total dry matter, chlorophyll content, and relative water content (RWC), but increased proline accumulation, activities of superoxide dismutase (SOD; EC 1.15.1.1), peroxidase (POD; EC. 1.11.1.7), catalase (CAT; EC. 1.11.1.6) and polyphenol oxidase (PPO; 1.10.3.1) and electrolyte leakage. Both foliar applications of KIN and IAA treatments overcame to variable extents the adverse effects of NaCl stress on the above mentioned physiological parameters. However, seed treatments with KIN or IAA did not improve salinity tolerance in maize plants. Furthermore, foliar application or seed treatments with KIN and IAA reduced the activities of antioxidant enzymes in the salt stressed-plants. Salt stress lowered some macronutrient concentrations [calcium (Ca) and potassium (K) in leaves and roots, phosphorus (P) in roots] but foliar application of both KIN and IAA increased Ca in both leaves and roots and P in leaves. Foliar application of IAA increased K concentrations in leaves of the salt-stressed plants. Foliar application of KIN and IAA, especially at 2 mM concentration, counteracted some of the adverse effects of NaCl salinity by causing the accumulation of proline and essential inorganic nutrients as well as by maintaining membrane permeability.     

INFLUENCE OF DIFFERENT SEED PRIMING METHODS FOR IMPROVING SALT STRESS TOLERANCE IN LETTUCE PLANTS

Seeds of lettuce, variety Romaine were subjected to different priming treatments such as water, potassium nitrate (KNO₃) and gibberellic acid (GA₃). Seedlings obtained from primed (Pr) and nonprimed (NP) seeds were grown in a hydroponic culture system supplemented with 0, 100 or 200 mM sodium chloride (NaCl). The different physiological and biochemical responses were studied 15 days after treatment. Under NaCl, the dry weight was higher in plants derived from hydro-primed (HP) seeds when compared to NP, osmoprimed (KNO₃P), and hormonal primed (GA₃P) ones. Under control and 100 mM NaCl treatment, malondialdehyde (MDA) content and EL did not show any correlation with activities of gaiacol peroxidase (GPX) and catalase (CAT), but did with the increase in reduced ascorbate (AsA) and total ascorbate contents. The results indicated that plants derived from HP seeds exhibited higher adaptive potential under salinity stress. Our findings suggest that a hydropriming technique can be used as a simple commercial approach to alleviate the effects of NaCl induced stress in lettuce plants.     

Effects of Potassium Sulfate on Adaptability of Sugarcane Cultivars to Salt Stress under Hydroponic Conditions

The effect of potassium sulfate (K₂SO₄) on adaptability of sugarcane to sodium chloride (NaCl) stress was investigated under hydroponic conditions. Two sugarcane cultivars, differing in salinity tolerance, were grown in half strength Johnson's solution at 80 mM NaCl with 0, 2.5 and 5.0 mM potassium (K) as K₂SO₄. Salinity disturbed above and below-ground dry matter production in both sugarcane cultivars. However, salt sensitive cultivar showed more reduction in shoot dry matter and higher root:shoot ratio compare to the salt tolerant cultivar under. Application of K significantly (p < 0.05) improved dry matter production in both sugarcane cultivars. The concentration of Na was markedly increased with increasing salinity; however, the application of K reduced its uptake, accumulation and distribution in plant tissues. Salinity induced reduction in K concentration, K-uptake, K utilization efficiency (KUE) and K:Na ratio in both sugarcane cultivars was significantly improved with the addition of K to the saline growth medium.     

Irrigation with salt water affects growth,yield, fruit quality,storability and marker-gene expression in cherry tomato

The use of saline water for plant production will become increasingly necessary over future decades. In some cases, fruit quality such as in tomato, can be improved by irrigation with saline water. The influence of different salt concentrations on physiological responses and the expression of some selected genes of cherry tomato (Solanum lycopersicum L), cv. West Virginia 106, was examined. Tomato plants were grown in peatmoss substrate and irrigated with 0, 25, 50, 75, 100 or 150?mM sodium chloride (NaCl) in a glasshouse. The NaCl treatments of 75, 100 and 150?mM salt resulted in shorter plants, decreased stem width, a lower plant dry weight, fewer flowers, and smaller leaf area, while yield was reduced by treatment with concentrations of 50?mM NaCl and above. Average fruit weight and fruit number were also negatively affected by treatment with 50?mM salt and above. Salinity treatment led to increased fruit total soluble solids, titratable acidity and firmness and improved the taste index. Salt-responsive marker genes identified in Moneymaker were also induced in cherry tomato but not at the highest salt concentrations. Our results indicated that cherry tomato treated with 25?mM NaCl produced fruit with improved quality in comparison with non-salinized control plants without compromising yield, while at 50 and 75?mM the improved fruit quality was accompanied by a reduction in yield.     

Ameliorative Effect of Hydro Gel Substrate on Growth,Inorganic Ions,Proline, and Nitrate Contents of Bean under Salinity Stress

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, CaSO_4, MgCl₂, MgSO₄, KCl, and K₂SO₄, and similarly NaCl, Na₂SO₄, CaCl₂, CaSO_4, 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.     

Calcium Sulfate Improves Salinity Tolerance in Rootstocks of Plum

ABSTRACT

Three vegetative rootstocks of plum (Prunus domestica), Marianna GF 8-1 (Prunus cerasifera × munsoniana), Myrobolan B (P. Cerasifera) and Pixy (P. Insititia) were grown in pots containing sand and irrigated with complete nutrient solution to investigate the effect of calcium sulfate supplied to the nutrient solution on plants grown under salt stress. Treatments were (1) control (C): nutrient solution alone; (2) S (salinity stress): 40 mM NaCl; (3) S+Ca1: 40 mM NaCl +2.5 mM calcium (Ca) and (4) S+Ca₂: 40 mM NaCl + 5 mM Ca. Calcium was supplied as CaSO₄. The plants grown under 40 mol L^?1 NaCl produced less dry matter and had lower chlorophyll content than those without NaCl. Supplementary CaSO₄ at both 2.5 and 5 mM concentrations ameliorated the negative effects of salinity on plant dry matter and chlorophyll content. Salt treatment impaired membrane permeability by increasing electrolyte leakage. The addition of calcium sulfate partially maintained membrane permeability. Sodium (Na) concentration in plant tissues increased in both leaves and roots of plants under the high NaCl treatment. Pixy had much lower Na. The CaSO₄ treatments lowered significantly the concentrations of Na in both leaves and roots. Pixy was more tolerant to salinity than the other two rootstocks. The accumulation of Na in leaves and roots indicates a possible mechanism whereby Pixy copes with salinity in the rooting medium, and/or may indicate the existence of an inhibition mechanism of Na transport to leaves. Concentrations of Ca and K were lower in the plants grown at high NaCl than in those under the control treatment, and these two element concentrations were increased by calcium sulfate treatments in both leaves and roots, but remained lower than control values in most cases.