Concentrations Of Na2CO3 Research Articles

Stabilizing Colloidal Particles against Salting-out by Shortening Surface Grafts.

A dramatic improvement is reported in the stability of colloidal particles when stabilizing surface grafts are systematically shortened from small polymers to single monomers. The colloidal dispersions consist of fluorinated latex particles, exhibiting a weak van der Waals attraction, with grafted steric layers of poly(ethylene glycol) (PEG) of different chain lengths. Using an effective salting-out electrolyte, Na2CO3, particle aggregates are detected above a threshold salt concentration that is independent of the particle concentration. The results are interpreted in terms of a sudden onset of nondispersibility of single particles, triggered by the solvent not completely wetting particle surfaces. By decreasing the PEG chain length, the threshold salt concentration is found to increase sharply. For grafts with just a single ethylene glycol group, dispersions remain stable up to exceedingly high concentrations of Na2CO3. However, on removal of the surface coverage altogether, the classical stability behavior of charge-stabilized dispersions is recovered. The behavior can be captured by a simple model that incorporates effective polymer-solvent interactions in the presence of an electrolyte.

Influence of alkali concentration, electric waveform, and frequency on the critical electric field strength of droplet–interface partial coalescence

During the process of electro-dehydration, the electric field strength should be set below a critical value (Ecrit) to inhibit droplet–interface partial coalescence. The alkali present in alkaline–surfactant–polymer flooding may affect Ecrit because they change the electrical properties of produced liquids. In view of this, this study investigated the effects of Na2CO3 solution concentration, electric field waveform, and frequency on the root mean square (RMS) values of Ecrit. The results show that elevated Na2CO3 concentrations increase Ecrit, owing to the enhanced solution conductivity which may affect the charge transfer during coalescence. The convection of ions is associated with penetration of fluid into the bulk phase and an increase in Na2CO3 concentration decreases the penetration velocity. Moreover, increasing the AC or pulsed electric field frequency can increase Ecrit, and the optimal waveform (i.e., with the largest Ecrit) varies with frequency. These findings will be useful for optimizing electro-coalescence systems.

The Cloud Point Behaviors and the Liquid–Liquid Equilibrium of L31—Inorganic Sodium Salt Aqueous Two-Phase Systems

The cloud point (CP) of triblock-copolymer L31 aqueous solution was determined with salting-out salts (Na2SO4/Na2CO3/NaF/NaCl/NaBr). The results show that all these salts can decrease the CP of L31 aqueous solution and form aqueous two-phase system (ATPS). With increasing concentrations of Na2SO4 and Na2CO3, an obvious phase inversion could be observed and phase inversion points were found. This was mainly due to the change in density, the salt-rich phase shifted from the top phase to the bottom phase. Meanwhile, the liquid-liquid equilibrium (LLE) data for L31-Na2SO4/Na2CO3/NaF/NaCl/NaBr ATPSs were measured at 288.15 K. The salt ability to decrease the CP and to induce the phase separation is as follows: Na2SO4 > Na2CO3, NaF > NaCl > NaBr. Finally, the order of anions that reduced the CP and caused phase separation was obtained as follows: SO42− >CO32−, F− > Cl− > Br−.

Promotive Effect of Bicarbonate Ion on Two-Electron Water Oxidation to Form H2 O2 Catalyzed by Aluminum Porphyrins.

Two-electron water oxidation initiated by one-electron oxidation of aluminum porphyrins (AlTMPyP) is an alternative water oxidation to the conventional four-electron pathway and could help to avoid the bottleneck subject of photon-flux density in artificial photosynthesis. Here, a dramatic enhancement of the reactivity by bicarbonate ion in the two-electron water oxidation to form H2 O2 is reported. An addition of sodium carbonate (Na2 CO3 ) controlled both catalytic current and product selectivity of the two-electron water oxidation to enhance the activity of AlTMPyP at pH≈10-11. Controlled potential electrolysis experiments at different concentrations of Na2 CO3 (10-100 mm) showed that peroxide selectivity was improved up to approximately 73 % by the increase of [Na2 CO3 ] added to the system. The promotion of the reaction cycle was induced by an enhanced dynamic capturing of H2 O2 from the hydroperoxy complex of AlTMPyP through an attack of a bicarbonate ion. The detailed electrochemical studies and product selectivity indicated that the bicarbonate ion served as a good cofactor for producing H2 O2 from water. At stronger alkaline conditions (pH 12.5), however, a retardative effect of the addition of Na2 CO3 on the catalytic reactivity was observed.

Ionic liquid‐mediated aqueous two‐phase system to enhance the partitioning of lignin

The aqueous two‐phase system (ATPS) is a promising and efficient alternative platform for the extraction, separation, and purification of biomolecules and bioproducts. In this work, four different imidazolium‐based ionic liquids with Cl− as anions and with different cations with aqueous Na2CO3 (inorganic salt) acting as the salting out agent were used to form the ATPS for the partitioning of lignin. The effects of the cation core and the length of the alkyl side chain of the ionic liquids on the formation of the ATPS were investigated using the phase diagram determined by the cloud point titration method, and the corresponding tie lines were measured and reported. It was found that the hydrophobicity of the ionic liquids plays a major role in the phase formation. The effects of the concentrations of IL, Na2CO3, and lignin as well as temperature on the partition coefficient and the extraction efficiency of lignin in the IL‐mediated ATPS were investigated, and the optimum conditions were established. It was found that the high extraction efficiency (∼99 %) and partition coefficient (∼47) of lignin in the IL‐mediated ATPS were achieved with the following parameters: Na2CO3 40 % (w/w); [HMIM]Cl 0.4 mol/L; lignin 0.006 mol/L; and at a temperature of 328 K. The thermodynamic study on lignin partitioning in the IL‐mediated ATPS was also investigated by varying the temperature range from 298–328 K, from which it was observed that the partitioning of lignin in the ATPS increases with an increase in temperature. This suggests that the process is endothermic in nature.

Fiber and seed type of hemp (Cannabis sativa L.) responded differently to salt-alkali stress in seedling growth and physiological indices

Hemp (Cannabis sativa L.) cultivars Yunma 5 (YM5, fiber-type) and Bamahuoma (BM, seed-type) were seriously affected by salt-alkali stress during germination, while the knowledge about the salt tolerance during seedling stage is deficient. Here, responses of hemp (Cannabis sativa L.) seedlings of the cultivars YM5 and BM to the stress of different concentrations of NaCl and Na2CO3 were investigated to explore the salt tolerance of hemp. Results showed that the plant height, dry weight and root length of YM5 and BM seedlings gradually decreased as the concentration of NaCl or Na2CO3 increased. Although physiological indices such as EC (Electrical conductivity), SOD (Superoxide dismutase) and Pro (Proline) increased as the salt concentration increased, the increase extent was significantly greater in YM5 than in BM. Under the conditions of 100 and 200 mM NaCl, BM had greater dry weight and root length, and lower Pro content than YM5. However, under the stress of 100 and 200 mM Na2CO3, the opposite results were recorded, with the exception for lower chlorophyll content and higher SOD activity in BM than in YM5. These findings indicated that BM had a stronger NaCl tolerance than YM5. Moreover, morphological indices of the two cultivars under Na2CO3 stress were stunted more than under NaCl stress, and the seedlings died when Na2CO3 concentration increased up to 300 mM. Some up-regulation of salt-tolerant genes were observed in the two hemp cultivars, a higher expression under NaCl stress than under Na2CO3 stress, and a higher expression in YM5 than in BM were recorded. Findings from the study indicated that hemp seedling is more sensitive to Na2CO3 stress, and the tolerance of hemp to salt stress varies with salt type and salt concentration, although both cultivars can withstand moderate doses of NaCl and Na2CO3.

Production of CuO nanoparticles using a simple precipitation method in a rotating packed bed with blade packings

CuO nanoparticles were produced using a simple precipitation method in a rotating packed bed with blade packings in continuous mode. The reactant and precipitant were CuSO4 and Na2CO3, respectively. The effects of the rotational speed, the flow rates of aqueous CuSO4 and Na2CO3, and the concentrations of CuSO4 and Na2CO3 on the size of the produced CuO nanoparticles were studied. The results thus obtained indicate that a lower rotational speed and smaller flow rates of aqueous CuSO4 and Na2CO3 yielded smaller CuO nanoparticles. However, increasing concentrations of CuSO4 and Na2CO reduced the size of the produced CuO nanoparticles. The smallest CuO nanoparticles, which had an average size of 54 nm, were produced at a rotational speed of 600 rpm, flow rates of aqueous CuSO4 and Na2CO3 of 0.3 L/min, a CuSO4 concentration of 0.3 mol/L, and an Na2CO3 concentration of 0.3 mol/L. The catalytic activity of the smallest CuO nanoparticles was evaluated by using them to degrade methylene blue with H2O2. CuO nanoparticles effectively activated H2O2 and so degraded methylene blue with an efficiency of 62% in 90 min.

Adoption of phase behavior tests and negative salinity gradient concept to optimize Daqing oilfield alkaline-surfactant-polymer flooding

A high performance surfactant formulation was developed using more universally accepted Winsor type phase behavior tests rather than relying primarily on interfacial tension (IFT) measurement for the first time for Daqing oilfield. A surfactant mixture of alkylbenzene sulfonate and fatty alcohol propoxylated ether sulfate was identified which was able to form middle-phase microemulsion with Daqing less reactive crude oil (acid number below 0.1 mg KOH/g crude), lower oil water IFT to ultralow level, and hold desired aqueous stability. Winsor type phase behavior tests at various water oil ratios (WORs) showed the optimum salinity changed slightly from 1.95% to 2% when WOR was increased from 5:5 to 9:1 due to the low reactivity of the Daqing crude oil. To investigate the significance of salinity on Daqing alkaline-surfactant-polymer (ASP) flooding, 4 salinity profiles were designed during coreflooding that corresponded to different types of microemulsions including III–III–I, I–III–I, II–III–I, and III–III–III. For each coreflooding, 0.3 pore volume (PV) of ASP slug with 0.3% total surfactant concentration and 0.2 PV polymer drive was injected. The results demonstrated when negative salinity gradient (3.0%–2.0%–0.5% Na2CO3 in waterflood, ASP, and polymer slugs) was applied, the highest incremental oil recovery of 45.9% original oil in place (OOIP) was achieved. If no Na2CO3 was added in water preflush prior to the injection of ASP slug, the lowest incremental recovery of 32.8% OOIP was observed. For a constant salinity profile at optimum salinity, an intermediate oil recovery (37.4%) was encountered. The measurement of surfactant and Na2CO3 concentrations in the effluents indicated that when negative salinity gradient (II–III–I) was applied, the surfactant loss in the porous media and the oil phase was moderate compared to the two corefloods with III–III–III (highest surfactant loss) emulsion and I–III–I emulsion (lowest surfactant loss). This implied that at optimized salinity profile, the surfactants were more close to hydrophobic-hydrophilic balance during the propagation in the reservoir, which showed the highest potential of increasing oil recovery for the Daqing Oilfield without significantly increasing chemical consumption.

Selective absorption of H2S with High CO2 concentration in mixture in a rotating packed bed

There is an increasing interest in the selective removal of hydrogen sulphide (H2S) from gas streams with a high concentration of carbon dioxide (CO2). In this study, a rotating packed bed (RPB) with short gas-liquid residence time and high mass-transfer efficiency is used for the selective absorption of H2S from gas mixtures with a high CO2 concentration with dinuclear cobalt-phthalocyanine sulfonate (PDS) as the catalyst. The effects of rotation speed, gas-liquid volume ratio, temperature, Na2CO3 and PDS concentrations on the desulfurization efficiency and selectivity were investigated. The experimental results show that the removal rates of H2S and CO2 are 99.13% and < 1%, respectively, at a rotation speed of 1000 r/min, a liquid-gas ratio of 8.5 L/m3, a temperature of 32 ± 2℃, a PDS concentration of 1.5 ppm, and a Na2CO3 concentration of 10 g/L. The high gravity technology has the advantages of high desulfurization selectivity and efficiency, and low liquid-gas ratio and Na2CO3 consumption.

Texturization of as-cut p-type monocrystalline silicon wafer using different wet chemical solutions

Implementing texturization process on the monocrystalline silicon substrate reduces reflection and enhances light absorption of the substrate. Thus texturization is one of the key elements to increase the efficiency of solar cell. Considering as-cut monocrystalline silicon wafer as base substrate, in this work different concentrations of Na2CO3 and NaHCO3 solution, KOH–IPA (isopropyl alcohol) solution and tetramethylammonium hydroxide solution with different time intervals have been investigated for texturization process. Furthermore, saw damage removal process was conducted with 10% NaOH solution, 20 wt% KOH–13.33 wt% IPA solution and HF/nitric/acetic acid solution. The surface morphology of saw damage, saw damage removed surface and textured wafer were observed using optical microscope and field emission scanning electron microscopy. Texturization causes pyramidal micro structures on the surface of (100) oriented monocrystalline silicon wafer. The height of the pyramid on the silicon surface varies from 1.5 to 3.2 µm and the inclined planes of the pyramids are acute angle. Contact angle value indicates that the textured wafer’s surface fall in between near-hydrophobic to hydrophobic range. With respect to base material absolute reflectance 1.049–0.75% within 250–800 nm wavelength region, 0.1–0.026% has been achieved within the same wavelength region when textured with 0.76 wt% KOH–4 wt% IPA solution for 20 min. Furthermore, an alternative route of using 1 wt% Na2CO3–0.2 wt% NaHCO3 solution for 50 min has been exploited in the texturization process.

Absorption of CO2 from modified flue gases of power generation Tarahan chemically using NaOH and Na2CO3 and biologically using microalgae

This research was carried out on the absorption of CO2 from the modified flue gases of power generation Tarahan using NaOH (sodium hydroxide) and Na2CO3 (sodium carbonate). The operation was conducted in a packed column absorber and then the output gases from the packed column was fed into photo-bioreactor for biological absorption. In the photo-bioreactor, two species of microalgae, N. occulata and T. chuii, were cultivated to both absorb CO2 gas and to produce biomass for algal oil. The aims of this research were, first, to determine the effect of absorbent flow rate on the reduction of CO2 and on the decrease of output gas temperature, second, to determine the characteristics of methyl ester obtained from biological absorption process. Flow rates of the absorbent were varied as 1, 2, and 3 l/min. The concentrations of NaOH and Na2CO3 were 1 M at a constant gas flow rate of 6 l/min. The output concentrations of CO2 from the absorber was analyzed using Gas Chromatography 2014-AT SHIMADZU Corp 08128. The results show that both of the absorbents give different trends. From the absorption using NaOH, it can be concluded that the higher the flow rate, the higher the absorption rate obtained. The highest flow rate achieved maximum absorption of 100%. On the other hand, absorption with Na2CO3 revealed the opposite trend where the higher the flow rates the lower the absorption rate. The highest absorption using Na2CO3 was obtained with the lowest flow rate, 1 l/min, that was 45,5%. As the effect of flow rate on output gas temperature, the temperature decreased with increasing flow rates for both absorbents. The output gas temperature for NaOH and Na2CO3 were consecutively 35 °C and 31 °C with inlet gas temperature of 50°C. Absorption of CO2 biologically resulted a reduction of CO2 up to 60% from the input gas concentration. Algal oil was extracted with mixed hexane and chloroform to obtain algal oil. Extracted oil was transesterified to methyl ester using sodium hydroxide as a catalyst. The results of in-situ transesterification method cannot be identified. Both microalgae achieved maximum yield at 2% catalyst concentration. Nannochloropsis occulata achieved the highest yield of algal oil that is 88.5%. The highest content of methyl ester from Nannochloropsis occulata was undecanoic acid methyl ester by 55.42% and the result from Tetraselmis chuii was palmitic acid methyl ester by 81.58%.

Interfacial Interaction and Emulsification of Crude Oil to Enhance Oil Recovery

This work addresses the characterisation of crude oil to examine opportunities for chemical enhanced oil recovery. Interfacial tension (IFT) studies were conducted for alkalis (NaOH and Na2CO3), surfactants (cetyltrimethylammonium bromide and sodium dodecyl sulphate), and their combinations. IFT studies revealed that the optimum concentrations of individual alkalis, NaOH and Na2CO3 are 0.1 wt%, 0.25 wt% for which IFT values of 5.15 × 10‒2 and 0.40 mN/m have been obtained respectively. For synergy of alkali-surfactant, the complex IFT behaviour indicated values in the range of 10‒2 mN/m. Emulsification and sandpack flooding studies affirmed that alkali and alkali-surfactant flooding can provide 24.25% and 38.79% residual oil recovery, respectively. [Received: August 20, 2017; Accepted: December 24, 2017]

The cloud point of aqueous solutions of ethoxylated monoalkylphenols in the individual state and in the presence of electrolytes

ABSTRACTThe cloud points tcp of aqueous solutions of ethoxylated monoalkylphenols, AF9-n (n = 8,9,10,12), were measured in the concentration (C) range of 0.25-40 wt.%. tcp increased as C decreased at C < 1 wt.%. At 1 < С < 10 wt.%, tcp changed insignificantly; Δtcp/tcp did not exceed 5%. Solutions transformed into the gel state at С > 10-20 wt.% and tcp sharply increased. The dependence of tcp on the length of the oxyethylene chains of ethoxylated nonylphenols at C = 1 wt.% can be described by the equation tcp = b·ln(n-n0), where n0 = 6. The cloud points of aqueous solutions (C = 1 wt.%) of the ethoxylated nonylphenols were measured at different concentrations of NaI, NaCl, NaF, Na2CO3, and Na2SO4 salts. For all of these solutions, tcp decreased in the presence of NaCl, NaF, Na2CO3, Na2SO4 and increased in the presence of NaI. To describe the dependence of tcp on the salt concentration, the equation was suggested, where and tcp are the cloud points of a neat aqueous solution of ethoxylated nonylphenols and of the solution in the presence of electrolytes, respectively.

Germination and growth response of flax (Linum usitatissimum) to salinity stress by different salt types and concentrations

ABSTRACTThis investigation was conducted to explore the effects of salt types with different concentrations on germination and growth parameters of flax seeds. The experiment was set out as a factorial experiment based on a completely randomized design with three replications. We used six kinds of salts (NaCl, CaCl2, CaCO3, Na2SO4, Na2CO3 and KCl) with concentrations of 0, 50, 100 and 200 mM. According to the results, the inhibitory effects of the five salt types differed substantially, especially in the case of CaCO3, Na2CO3 and Na2SO4. Inhibitory effects of these salts were very strong compared to those of NaCl and CaCl2. Germination of flax seeds by various salts was in the order of NaCl > CaCl2 > KCl > Na2CO3 > Na2SO4 > CaCO3. The effect of salt concentration was obvious, too. Seeds of flax were able to germinate even in 200 mM NaCl, but they only germinated in distilled water or at very low CaCO3, Na2CO3 and Na2SO4 concentrations (50 mM).

Investigation of the growth parameters of hydrothermal ZnO nanowires for scale up applications

Zinc oxide nano-wires (ZnO NWs) are synthesized reproducibly with high yield via a low temperature hydrothermal technique. The influence of the growth duration time, growth temperature, zinc precursor and base concentration of Na2CO3 on the morphology of NWs is investigated. The growth products are characterised using scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL). SEM analysis shows that the optimum growth temperature is 140°C and finds that length and diameter of ZnO NWs have a relationship with growth duration time and base concentrations of Na2CO3. In addition, it is reported that a high (∼90%) yield of ZnO NWs can be synthesised via using any of three different precursors: zinc chloride, zinc acetate and zinc nitrate. TEM and XRD results indicate the high purity and the single crystalline nature of the ZnO NWs. XPS confirms the absence of sodium contaminants on the surface and indicates a near flat band surface condition. PL shows a large visible band in the yellow part of the spectrum, and a small exciton emission peak, indicating a large defect concentration, which is reduced after annealing in air.

Comparative evaluation of different pretreatment methods on biogas production from paddy straw

The present investigations observed the effect of chemical, enzymatic, biological and micro-wave pretreatment on paddy straw for enhancement of biogas production. Chopped and soaked paddy straw was subjected to chemicals Na2CO3 (1%) and NaOH (2%) concentrations, microwave irradiation (720 watt, 30 min), fungal (spawn impregnated, 7 days) and crude silicase (24 hrs) pretreatment. The proximate and chemical analysis showed 16.0% and 12.1% reduction in lignin and silica content in the case of Na2CO3 pretreated paddy straw whereas 23.0% and 46.8% reduction was observed in enzymatic pretreatment with 43.7% and 31.1% enhancement in biogas production respectively. This clearly indi-cates that Pleurotus ostreatus MTCC 142 is silicolytic as well as ligninolytic in nature. Enzymatic pre-treatment was also compared with, microwave (30 min) and fungal pretreatment which showed 31.2% and 32.8% reduction in silica content enhancing biogas production by 19.7% and 42.6% respectively. NaOH pretreatment showed a maximum increase in biogas production i.e. 49.7% as compared to 1% pretreated sample which showed 28.5% enhancement. The results indicated that the NaOH pretreatment was one of the potential methods to increase biogas production of paddy straw.

Investigation of the solid electrolyte interphase on hard carbon electrode for sodium ion batteries

The electrochemical performance of hard carbon (HC)/Na cells with NaPF6 in a mixture of EC/DEC (1:2, v/v) has been investigated in the voltage range of 0.05–2V. An initial reversible capacity of 162mAhg−1 is observed. With continuous cycling, the reversible capacities fluctuate slightly and obtain a value of 183mAhg−1 on the 25th cycle. Ex-situ surface analysis of cycled HC electrodes has been conducted by a combination of scanning electron microscopy (SEM), infrared spectroscopy with attenuated total reflectance (IR-ATR) and X-ray photoelectron spectroscopy (XPS). The ex-situ surface analysis suggests that the major composition of solid electrolyte interphase (SEI) formed on the surface of HC electrode is sodium ethylene dicarbonate (SEDC) and NaF with lower concentrations of sodium alkyl carbonates and Na2CO3 which is similar with that reported in lithium ion batteries.

Physiological and biochemical responses of the green alga Pachycladella chodatii (SAG 2087) to sodicity stress

The effects of various concentrations of different carbon sources (Na2CO3 and NaHCO3) as sodicity stress on growth parameters, CO2 consumption rate, enzyme activity, intracellular lipid content, and fatty acid profiles of Pachycladella chodatii were studied. Generally, the total chlorophyll was increased by increasing the concentrations of Na2CO3 and NaHCO3. The biomass productivity as well consumption rate of carbon dioxide of P. chodatii reached the highest values with increasing concentrations of Na2CO3 and NaHCO3. The soluble protein content of P. chodatii was highest at the lowest Na2CO3 and NaHCO3 concentrations. The addition of different concentrations of Na2CO3 and NaHCO3 in the growth media induces lipoxygenase and superoxide dismutase specific activity. Catalase and total antioxidant enzymes were increased by supplementing the growth media with 60 and 45mgl−1 of Na2CO3 and NaHCO3, respectively. Hydrogenase uptake activity in P. chodatii increased gradually in all treated cultures with the time elapsed recording the maximum activity after 11days of growth especially at 60, 45mgl−1 of Na2CO3 and NaHCO3 respectively. Lipids content was increased at low concentration of Na2CO3 (40 and 15mgl−1) and NaHCO3 (60, 45mgl−1) respectively. Subsequent to algal cultivation in different concentrations of Na2CO3, the cultures were filtered and biodiesel was prepared by direct esterification of dry algal biomass. Methyl esters of palmitic, elaidic and stearic acids represented the major components while myristic, pentadecanoic and 9,12-octadecenoic acids represented a minor component of biodiesel produced from P. chodatii treated with different concentrations of Na2CO3 and NaHCO3.

Effects of Na2CO3 on seed germination, seed reserve utilizationand seedling growth in bitter vetch (Vicia ervilia L.)

Alkalinity is one of the main limiting factors of seed germination in alkaline soils. The aim of this study was to evaluate the effects of Na2CO3 levels (0, 5, 10, 15, 20 and 25 mM) on seed germination, seed reserve utilization and seedling vigour of three local bitter vetch cultivars (Buinzahra, Shahreza and Tarom). The results indicated that increasing Na2CO3 concentrations caused a decrease in germination percentage (GP), germination rate (GR), seedling length, seedling dry weight (SLDW) and seed reserve utilization efficiency (SRUE). The rate of reduction in shoot length in comparison with the control in different concentrations of Na2CO3 was detected from Buinzahra as 30-92%, Shahreza 39-97% and Tarom 13-83%. Decrease in root length was more than shoot length in all the cultivars at each Na2CO3 level, as compared to the control. The weight of mobilized seed reserve (WMSR) and seed reserve depletion percentage (SRDP) decreased with increasing Na2CO3 levels up to 10 mM in Buinzahra and Tarom cultivars and up to 15 mM in Shahreza. WMSR and SRDP then rapidly raised with higher alkalinity levels. These results suggest that reduction of seed germination and decline in seedling dry weight in response to alkalinity stress is a consequence of decline in seed reserve utilization efficiency.

Effect of abiotic stress on growth parameters and steviol glycoside content in Stevia rebaudiana (Bertoni) raised in vitro

Stevia rebaudiana (Bertoni) is a producer of diterpenoid steviol glycoside (SGs), which is highly sweet compound, non-toxic, non-mutagenic and has negligible effect on blood glucose. Therefore, the aim of present work was to study the effect of four chemicals (NaCl, Na2CO3, Proline and Polyethylene glycol) on growth parameters and SGs production in S. rebaudiana shoots cultured in vitro. For this, in vitro raised nodal explants of Stevia were cultured on MS medium supplemented with 2.0mgl−1 of kinetin and different concentrations of NaCl (0.05–0.20%), Na2CO3 (0.025–0.10%), Proline (2.5–10mM) and Polyethylene glycol (2.5–10%) for four weeks, and incubated at 24±1°C and 22.4μmolm−2s−1 light intensity provided by white fluorescent tubes with a photoperiod of 16h. Among all the chemicals tested, NaCl and Proline showed good growth of shoots but Na2CO3 and PEG showed poor growth in comparison to control. A significant reduction in shoot growth (i.e., shoot length, number of shoots per node and multiplication fold) was noticed with different concentrations of chemicals tested (P≤0.05). Maximum shoot length (5.83±0.01cm) was observed with 7.5mM of Proline concentration followed by 0.05% NaCl (5.45±0.08cm), 0.025% Na2CO3 (4.05±0.06cm) and 2.5% PEG (2.52±0.06cm). Stress showed better results pertaining to SGs production in stress treated in vitro plants than control. Maximum (2.60%) amount of total SGs (Stevioside and Rebaudioside A) were found with shoots treated with 0.025% Na2CO3 followed by 5.0mM Proline (1.65%), 0.10% NaCl (1.25%) and 5% PEG (1.15%), which were 3.3, 2, 1.6 and 1.5 times higher than control (0.79%) respectively. It can be concluded that, in spite of causing some growth reduction, application of chemical stress can enhance the production of SGs up to three fold compared to control plants.