Salt Tolerance Properties Research Articles

Effect of the vacuolar Na+/H+ antiporter transgene in a rice landrace and a commercial rice cultivar after its insertion by crossing

The vacuolar Na+/H+ antiporter is known to alleviate saline stress by sequestering Na+ in both wild-type Arabidopsis and rice and when over-expressed in many transgenic plants. Here we report on the effect of the NHX1 transgene on the salt tolerance properties it confers to a rice landrace and a commercial cultivar suitable for the dry winter season, but which suffers loss due to seasonal stresses, particularly in the coastal areas. The Nipponbare Na+/H+ antiporter 1.9 kb cDNA was cloned into pCAMBIA1305.1 under the control of the CaMV35S promoter and transformed into tissue-culture-responsive rice landrace Binnatoa (BA). The best-expressing transgenic line at T2 was found to be significantly tolerant at the seedling stage and was advanced to T3. The transgene was then transferred to the tissue-culture recalcitrant farmer-popular commercial rice genotype, BRRIdhan 28 (BR28) by crossing. The data generated both from semi-quantitative RT-PCR and western blot hybridization revealed that the transgene showed similar expression in the crossbred BR28 plants and BA transgenic line. Comparative stress tolerance tests, however, revealed that the BR28 crossbred lines were significantly less tolerant than its transgenic parent BA at both seedling and reproductive stages. A single successful transgenic event may therefore not show the same performance in the recipient genetic background, if introgressed by crossing.

Antimicrobial functionalization of silicone surfaces with engineered short peptides having broad spectrum antimicrobial and salt-resistant properties

Catheter-associated urinary tract infections (CAUTIs) are often preceded by pathogen colonization on catheter surfaces and are a major health threat facing hospitals worldwide. Antimicrobial peptides (AMPs) are a class of new antibiotics that hold promise in curbing CAUTIs caused by antibiotic-resistant pathogens. This study aims to systematically evaluate the feasibility of immobilizing two newly engineered arginine/lysine/tryptophan-rich AMPs with broad antimicrobial spectra and salt-tolerant properties on silicone surfaces to address CAUTIs. The peptides were successfully immobilized on polydimethylsiloxane and urinary catheter surfaces via an allyl glycidyl ether (AGE) polymer brush interlayer, as confirmed by X-ray photoelectron spectroscopy and water contact angle analyses. The peptide-coated silicone surfaces exhibited excellent microbial killing activity towards bacteria and fungi in urine and in phosphate-buffered saline. Although both the soluble and immobilized peptides demonstrated membrane disruption capabilities, the latter showed a slower rate of kill, presumably due to reduced diffusivity and flexibility resulting from conjugation to the polymer brush. The synergistic effects of the AGE polymer brush and AMPs prevented biofilm formation by repelling cell adhesion. The peptide-coated surface showed no toxicity towards smooth muscle cells. The findings of this study clearly indicate the potential for the development of AMP-based coating platforms to prevent CAUTIs.

Cloning, characterization and expression of a chloroplastic fructose-1,6-bisphosphatase from Porteresia coarctata conferring salt-tolerance in transgenic tobacco

A gene coding for the chloroplastic fructose 1,6-bisphosphatase (PcCFR) in Porteresia coarctata Tateoka (Roxb.), a halophytic wild rice, has been isolated along with its rice (Oryza sativa; var. indica) homologue (OsCFR), cloned and sequenced. Comparison between the nucleotide and deduced amino acid sequences of these two revealed a difference in five amino acid residues, namely Glu14, Thr24, Ala48, Ala163 and Arg296 in OsCFR which have been found to be replaced by Ser14, Ile24, Ser48, Ser163 and Lys296 in PcCFR respectively. The purified recombinant PcCFR is found to retain its enzymatic activity in presence of up to 500 mM NaCl in vitro as opposed to OsCFR, which is inactivated even at lower salt concentration. The six in vitro point mutant proteins of PcCFR showed varied degree of sensitivity towards high salt, with the maximum OsCFR-like effect in the triple mutant S14A-S48A-S163A suggesting a possible concerted role of all three serine residues in the in vitro salt tolerance property of PcCFR protein. Transgenic tobacco plants with chloroplast targeted PcCFR and OsCFR gene(s) have been developed under constitutive expression of CaMV 35S promoter and NOS terminator. The PcCFR transgenics showed better plant growth during exposure to salt stress in comparison to either the OsCFR or the empty vector transformed plants. The PcCFR transgenics also revealed enhanced photosynthetic efficiency coupled with protection to both photodamage of PSII and chlorophyll degradation through better reactive oxygen species scavenging at higher concentration of NaCl during late salt-stress growth.

Preparation of polyacrylamide/graphite oxide superabsorbent nanocomposites with salt tolerance and slow release properties

Novel polyacrylamide/graphite oxide (PAM/GO) superabsorbent nanocomposites were synthesized by a simple solution polymerization of acrylamide using N,N ′-methylenebisacrylamide as crosslinker and ammonium persulfate as initiator. The well dispersion of GO nanoplatelets in the polymeric network results in a remarkable improvement on the comprehensive swelling performance of the resulting superabsorbent nanocomposites. The water absorption experimental results show that the superabsorbent nanocomposites could absorb water as twice as that of crosslinked polyacrylamide (PAM) superabsorbent with a weight gain of 400 g g−1 with a low loading of GO. The salt tolerance and water-retention ability of the resulting PAM/GO superabsorbent nanocomposites are also enhanced compared with PAM. Moreover, by embedding of ammonium salt into PAM/GO network, the PAM/GO superabsorbent nanocomposites also exhibit a slow release behavior of ammonium salt from network when swelling in water, which makes the PAM/GO superabsorbent nanocomposites multifunctional absorbent materials with great potential for agricultural and horticultural applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Screening of probiotic lactobacilli for inhibition of Shigella sonnei and the macromolecules involved in inhibition

A total of 91 lactobacilli were screened for antimicrobial activity against Shigella sonnei. Agar-well assay showed that 16 lactobacilli displayed strong antibacterial activity against S. sonnei. The nature of these antimicrobial agents were investigated and shown to be dependent on their production of organic acids. Adhesion tests showed that 6 lactobacilli demonstrated good adherence to HT-29 cells, of these Lactobacillus johnsonii F0421 were selected for acid and bile salt tolerance properties. We further research on L. johnsonii F0421 inhibition of S. sonnei adhesion to HT-29 cells. The result showed that L. johnsonii F0421 exhibited significant inhibitory activity and excluded, competed and displaced adhered S. sonnei by 48%, 38% and 33%, respectively. In order to elucidate the inhibitory functions of macromolecules involved in L. johnsonii F0421, the cells were treated with 5 m LiCl, 0.05 m sodium metaperiodate and heating and assayed for inhibition activity. The results suggested a role of S-layer proteins on L. johnsonii F0421 cells in inhibition of the adhesion process, but carbohydrates do not seem to be involved. SDS-PAGE analysis confirmed the presence of S-layer proteins with dominant bands of approximately 40 kDa. In addition, 100 μg/well of S-layer proteins from L. johnsonii F0421 cells were effective in inhibiting adhesion of S. sonnei to HT-29 cells. These findings suggest that L. johnsonii F0421 possesses the capacity for inhibition of S. sonnei activity as well as probiotic properties, which could serve as a potential novel and effective probiotic strain for use in the food industry.

The Effect of Micro-Structure of CMC on Stability of Milk Beverage

In this paper, two types of carboxymethyl cellulose samples (CMCe and CMCm), which served as stabilizer to improve the taste and the shelf life of milk beverage, were prepared at different bath ratio and reaction media system. The influencing factors of samples’ discrepancy structure with the ways of preparation were invested. After this, its application basic properties of the samples were searched in milk beverage. The macromolecule structure and morphologies and application performances were analyzed by NMR and SEM. The effect of molecular structures and their acid salt tolerance property of two CMC on milk beverage such as sedimentation ratio and stability of milk micelle were also investigated. The results showed that the distribution of the CH2COO- group on anhydroglucose unit (AGU) of CMCe obtained at low bath ratio in ethanol was C2> C6> C3, whereas C6＞C2＞C3 which showed the highest substitution in C6 position, was observed in CMCm prepared in mixed isopropanol and ethanol at high bath ratio. In comparison with CMCe at same viscosity, the CMCm showed higher ratio of acidity to viscosity (AVR), higher temperature resistance, lower precipitation ratio (AVR) and better stability. As shown in SEM image of treated milk powder made from milk beverager, the structure of milk protein with CMCm formed continuous network and homogeneous morphology. However the structure of milk protein with CMCe showed tendency of aggregation.

Synthesis and Characterization of Silver-Histidine Complex Doped Montmorillonite Antibacterial Agent

In this paper a novel colorless and salt-tolerant silver-histidine complex doped montmorillonite (Na-MMT) antibacterial agent (SHMMT) power was synthesized by ion exchange reaction using silver-histidine complex ion [Ag (his)] + as precursor, and characterized by atomic absorption spectrophotometer (AAS) and power X-ray diffraction (XRD). The antibacterial activities against Pseudoalteromonas carrageenovora were examined by a modified broth dilution test and the plate counting method. The salt-tolerant property was determined by the antibacterial activities of the sea water soaked SHMMT. The results showed that the Ag loading amount of SHMMT powder reached 1.7mmol/g, far more than the cationic exchange capacity (CEC) of Na-MMT. SHMMT powder had high bacterial activity eventhough it was soaked in the sea water for 30 days. 1

Cyclodextrin and methacrylic acid octyl phenols poly(ethylene oxide) ester‐induced synergistic effect in a novel poly(AM‐co‐A‐β‐CD‐co‐AE) polymer

AbstractOwing to superior properties such as temperature resistance and salt tolerance etc., modified polyacrylamide (PAM) as one of the main injected polymers has been widely investigated to enhance oil production in reservoirs. Herein, a novel poly(AM‐co‐A‐β‐CD‐co‐AE) polymer was synthesized by utilizing β‐CD and AE to copolymerize with AM and characterized by FT‐IR and SEM. Furthermore, the temperature resistance and salt tolerance of poly(AM‐co‐A‐β‐CD‐co‐AE) polymer were explored. The results showed that the presence of the poly(AM‐co‐A‐β‐CD‐co‐AE) polymer better achieved temperature resistance and salt tolerance properties than is the case with PAM, which has potential application for enhancing oil recovery in the high‐temperature and high‐mineralization oilfield. On the other hand, the inhibition performance of poly(AM‐co‐A‐β‐CD‐co‐AE) polymer as a corrosion inhibitor was evaluated by SEM and electrochemical techniques. SEM observations of the carbon steel surface confirmed the protective role of the corrosion inhibitor. The results of potentiodynamic polarization and EIS measurements on the corrosion inhibition of carbon steel samples in 0.5 M sulfuric acid solutions revealed that the highest inhibition efficiency of it over 90% was obtained, indicating poly(AM‐co‐A‐β‐CD‐co‐AE) polymer acts as a more efficient corrosion inhibitor for carbon steel.

Characterization of a salt-tolerant xylanase from Thermoanaerobacterium saccharolyticum NTOU1

A xylanase gene was PCR-cloned from Thermoanaerobacterium saccharolyticum and expressed in Escherichia coli. The xylanase (XynA) consisted of a signal peptide, glycoside hydrolase family 10 domains, carbohydrate-binding modules, and surface layer homology domains. It was optimally active at 70-73°C and at pH 5-7. It had enhanced activity with NaCl with optimal activity at 0.4M but was tolerant up to 2M NaCl. The thermostable and salt-tolerant properties of this xylanase suggest that it may be useful for industrial applications.

Effect of pesticides on phosphate solubilization by Bacillus sphaericus and Pseudomonas cepacia

Intensive screening of phosphate solubilizing bacteria with genetic potential for increased tolerance to high salt, high pH and high temperature could enhance production of food and forage in semi-arid regions. Emphasizing particularly on this hypothesis 165 phosphate solubilizing bacteria was isolated. Among these, two cultures Bacillus sphaericus and Pseudomonas cepacia were selected on the basis of salt tolerance property and PS activity with different forms of phosphates. In the present investigation both these culture were assessed for the effect of six different pesticides, to confirm its successful realistic application as microbial inoculants in actual farm conditions. Both cultures showed better phosphate solubilizing activity with phosphate containing pesticides. Among these two isolates P. cepacia was a better performer in terms of phosphate solubilizing activity with different pesticides. It may be due to its well documented extra ordinary, versatile metabolic activity. The present study may prove them to be potential candidates to be used as microbial inoculants.

Porteresia coarctata (Roxb.) Tateoka, a wild rice: a potential model for studying salt‐stress biology in rice

Porteresia coarctata (Syn = Oryza coarctata) is a tetraploid wild rice growing abundantly in the coastal region of India and some other Asian countries. The salt tolerance property of this mangrove associate has been dealt with by a number of workers earlier. The distinct morphology and leaf architecture enabling the plant to exclude salt is a characteristic feature of Porteresia in comparison with Oryza sp. A number of genes have been isolated and characterized from Porteresia that are related to the salt-tolerance property of the plant. Evidence have accumulated that some pathways critical to salt tolerance are in operation in Porteresia of which the inositol metabolic pathway has been recently elaborated. Some of the enzymes of Porteresia have been shown to function as salt-tolerant under in vitro studies giving a clue that this wild halophytic rice may have evolved genes and proteins capable of functioning under a salt environment. Bioprospecting of such genes and proteins coupled with genomic and proteomic approaches remain an exciting area of research in evaluating this plant as a model for salt tolerance for the rice plant.

4-(1H-imidazol-1-yl) aniline: A new ligand of mixed-mode chromatography for antibody purification

4-(1H-imidazol-1-yl) aniline (AN) was immobilized on Sepharose CL-6B (AN-Sepharose) for use as a new ligand of mixed-mode chromatography. Adsorption equilibria of immunoglobulin G (IgG) and bovine serum albumin (BSA) to AN-Sepharose were studied at extensive pH values (4.0–8.8) and salt concentrations (0–1.0 mol/L). Static binding studies indicated that AN-Sepharose had a good salt-tolerance property for IgG adsorption up to 1.0 mol/L NaCl. This was attributed to the combined ligand–protein interactions (hydrophobic interaction, hydrogen bonding and charge transfer interaction). By contrast with BSA, AN-Sepharose showed a high binding selectivity for IgG at NaCl > 0.2 mol/L. Dynamic binding capacities (DBC) of IgG and BSA at 10% breakthrough were measured at pH 4.0–8.8 by frontal analysis chromatography. IgG had DBC values over 40 mg/mL at pH 7.0–8.8, and the maximum reached 59 mg/mL at pH 8.0. At pH 5.0, a distinct drop in DBC to 8.5 mg/mL was observed, but that for BSA kept over 22 mg/mL. The result suggested that IgG could be selectively desorbed from AN-Sepharose by decreasing pH to about 5. Therefore, compared to BSA, AN-Sepharose exhibited a dual-selectivity for IgG in both adsorption and elution. Purification of IgG from bovine serum also confirmed the dual-selectivity. IgG purity of the pooled fractions by elution at pH 4.0, 4.5 and 5.0 reached 55% and the highest purity, 80%, was obtained at pH 4.5. The average purification factor of IgG was over 25. The results indicate that AN is a promising ligand of mixed-mode chromatography for antibody purification from a complex feedstock.

Preparation and characterisation of crosslinked waxy potato starch

Abstract Using waxy potato starch as the raw material, the preparation, and determination of physical and chemical properties of acetylated distarch adipate (ADA) were studied systematically. The experimental variables investigated include temperature, pH, and reaction time, which all have influence on the degree of substitution (DS) of crosslinked waxy potato starch. Results show that the optimal reaction was obtained at a pH range of 9.0–9.5, a temperature of 35 °C, and a reaction time of 2 h. The structures of ADA starch were characterised by FT-IR, and the results indicate a new absorption peak at 1732 cm −1 which is assigned to the C O stretching vibration. It was found through polarised light microscopy and scanning electron microscopy (SEM) that the starch granule structure did not substantially change after crosslinking. The modified waxy potato starch paste exhibited excellent viscosity stability, acid resistant, salt tolerance properties and good breakdown. The swelling of ADA starch granules was gradual over a wide range of temperatures.

Functional comparison of plasma-membrane Na+/H+ antiporters from two pathogenic Candida species

BackgroundThe virulence of Candida species depends on many environmental conditions. Extracellular pH and concentration of alkali metal cations belong among important factors. Nevertheless, the contribution of transporters mediating the exchange of alkali metal cations for protons across the plasma membrane to the cell salt tolerance and other physiological properties of various Candida species has not been studied so far.ResultsThe tolerance/sensitivity of four pathogenic Candida species to alkali metal cations was tested and the role of one of the cation transporters in that tolerance (presumed to be the plasma-membrane Na+/H+ antiporter) was studied. The genes encoding these antiporters in the most and least salt sensitive species, C. dubliniensis and C. parapsilosis respectively, were identified, cloned and functionally expressed in the plasma membranes of Saccharomyces cerevisiae cells lacking their own cation exporters. Both CpCnh1 and CdCnh1 antiporters had broad substrate specificity and transported Na+, K+, Li+, and Rb+. Their activity in S. cerevisiae cells differed; CpCnh1p provided cells with a much higher salt tolerance than the CdCnh1 antiporter. The observed difference in activity was confirmed by direct measurements of sodium and potassium efflux mediated by these antiporters.ConclusionWe have cloned two genes encoding putative Na+/H+ antiporters in C. parapsilosis and C. dubliniensis, and characterized the transport properties of encoded proteins. Our results show that the activity of plasma-membrane Na+/H+ antiporters is one of the factors determining the tolerance of pathogenic Candida species to high external concentrations of alkali metal cations.

Separation of nattokinase fromBacillus subtilis fermentation broth by expanded bed adsorption with mixed-mode adsorbent

Mixed-mode hydrophobic/ionic matrices exhibit a salt-tolerant property for adsorbing target protein from high-ionic strength feedstock, which allows the application of undiluted feedstockvia an expanded bed process. In the present work, a new type of mixed-mode adsorbent designed for expanded bed adsorption, Fastline PRO®, was challenged for the capture of nattokinase from the high ionic fermentation broth ofBacillus subtilis. Two important factors, pH and ion concentration, were investigated with regard to the performance of nattokinase adsorption. Under initial fermentation broth conditions (pH 6.6 and conductivity of 10 mS/cm) the adsorption capacity of nattokinase with Fastline PRO was high, with a maximum capacity of 5,350 U/mL adsorbent. The elution behaviors were investigated using packed bed adsorption experiments, which demonstrated that the effective desorption of nattokinase could be achieved by effecting a pH of 9.5. The biomass pulse response experiments were carried out in order to evaluate the biomass/adsorbent interactions betweenBacillus subtilis cells and Fastline PRO, and to demonstrate a stable expanded bed in the feedstock containingBacillus subtilis cells. Finally, an EBA process, utilizing mixed-mode Fastline PRO adsorbent, was optimized to capture nattokinase directly from the fermentation broth. The purification factor reached 12.3, thereby demonstrating the advantages of the mixed-mode EBA in enzyme separation.

A Novel Salt-tolerant l-myo-Inositol-1-phosphate Synthase from Porteresia coarctata (Roxb.) Tateoka, a Halophytic Wild Rice: MOLECULAR CLONING, BACTERIAL OVEREXPRESSION, CHARACTERIZATION, AND FUNCTIONAL INTROGRESSION INTO TOBACCO-CONFERRING SALT TOLERANCE PHENOTYPE

l-myo-Inositol-1-phosphate synthase (EC 5.5.1.4, MIPS), an evolutionarily conserved enzyme protein, catalyzes the synthesis of inositol, which is implicated in a number of metabolic reactions in the biological kingdom. Here we report on the isolation of the gene (PINO1) for a novel salt-tolerant MIPS from the wild halophytic rice, Porteresia coarctata (Roxb.) Tateoka. Identity of the PINO1 gene was confirmed by functional complementation in a yeast inositol auxotrophic strain. Comparison of the nucleotide and deduced amino acid sequences of PINO1 with that of the homologous gene from Oryza sativa L. (RINO1) revealed distinct differences in a stretch of 37 amino acids, between amino acids 174 and 210. Purified bacterially expressed PINO1 protein demonstrated a salt-tolerant character in vitro compared with the salt-sensitive RINO1 protein as with those purified from the native source or an expressed salt-sensitive mutant PINO1 protein wherein amino acids 174-210 have been deleted. Analysis of the salt effect on oligomerization and tryptophan fluorescence of the RINO1 and PINO1 proteins revealed that the structure of PINO1 protein is stable toward salt environment. Furthermore, introgression of PINO1 rendered transgenic tobacco plants capable of growth in 200-300 mm NaCl with retention of approximately 40-80% of the photosynthetic competence with concomitant increased inositol production compared with unstressed control. MIPS protein isolated from PINO1 transgenics showed salt-tolerant property in vitro confirming functional expression in planta of the PINO1 gene. To our knowledge, this is the first report of a salt-tolerant MIPS from any source.

New processing of lupin protein isolates and functional properties.

A growing demand for functional plant proteins could be identified, which properties are customized for specific applications and formulations as food ingredients. Native lupin proteins (alpha, beta, gamma) conglutin have a good solubility at appropriately chosen conditions. A novel procedure has been proposed to maintain the native protein properties. Lupin proteins are extracted from hexane deoiled lupin. The protein product type E comprises high molecular weight proteins (alpha, beta-conglutin), which are separated using alkaline extraction and acid precipitation procedures. The protein product type F is enriched in the gamma-conglutin fraction and is separated from the acid pre-extract applying cross flow filtration at pH 7-8. For the zirconium oxide membrane the filtration rate can be increased by appropriately chosen pH conditions up to 70 l/m2h. Lupin protein fraction (type E and F) are highly soluble protein isolates with outstanding emulsification, salt tolerance and foaming properties. These new lupin proteins (type E and F) offer extremely interesting properties for application in food systems and are available from pilot plant fractionation.

Chloroplast fructose-1,6-bisphosphatase from Oryza differs in salt tolerance property from the Porteresia enzyme and is protected by osmolytes

Salinity exerted a distinctly differential effect on fructose-1,6-bisphosphatase (EC. 3.1.3.11) isolated from salt-sensitive and salt-tolerant rice ( Oryza sativa) varieties. Cytosolic and chloroplastic isoforms of the enzyme from salt-sensitive rice seedlings exhibited decreased catalytic activity during growth in the presence of salt. Furthermore, chloroplastic fructose 1,6-bisphosphatase purified from salt-sensitive ( O. sativa cv. IR26) and from the wild halophytic rice Porteresia coarctata differed in their in vitro salt tolerance property although they exhibited otherwise identical biochemical and immunological properties. This decline in enzyme activity was not correlated with de novo synthesis of the chloroplastic fructose-1,6-bisphosphatase protein in the presence of salt. The inhibitory effect of increasing concentration of NaCl on in vitro enzymatic activity could be prevented by preincubation of the enzyme with a number of osmolytes with an effectiveness in the order polyol>sugars. Further, the intrinsic tryptophan fluorescence of the purified rice enzyme is altered in vitro with increasing NaCl concentration which could be prevented by preincubation with inositol. Purified chloroplastic fructose-1.6-bisphosphatase from P. coarctata however, exhibits no such inhibition of enzyme activity in vitro or alteration in tryptophan fluorescence with increasing NaCl concentration.

Characterization of the Na +-ATPase gene ( ZENA1) from the salt-tolerant yeast Zygosaccharomyces rouxii

In order to clarify the relationship between the salt tolerance of Zygosaccharomyces rouxii and the function of Na +-ATPase, a gene which exhibited homology to the Na +-ATPase gene ( ZENA1) of Saccharomyces cerevisiae was isolated from Z. rouxii. This newly isolated gene ( ZENA1) encoded a product of 1048 amino acids. The predicted amino-acid sequence of Zena1p was highly homologous to that of S. cerevisiae Ena1p and Ena2p, and Schwanniomyces occidentalis Ena1p and Ena2p, but showed low homology to that of Zpma1p, which is the product of the Z. rouxii plasma membrane H +.ATPase gene ( ZENA1). Zena1p shares the peptide motifs which have been suggested to participate in the function of ATPase. Expression of ZENA1 was observed, but was independent of NaCl shock. When ZENA1 was expressed in salt-sensitive S. cerevisiae under the regulation of a GAL1 promoter by using the expression vector pYES2, salt tolerance of the transformants was observed. The growth characteristics of Zena1Δ-disruptants of Z. rouxii and the pH profiles of their plasma membrane ATPase activity were almost the same as those of the wild-type strain, indicating that the function of Zena1p is of little relevance to the salt tolerance property of Z. rouxii. By considering the close relationship between the salt tolerance of Z. rouxii and the function of its Na +/H +-antiporter, we concluded that the extrusion of Na + across the plasma membrane in Z. rouxii cells might be carried out mainly via the function of the Na +/H +-antiporter in a high salinity environment.

Growth of Wheat and Gram Under Saline-Alkali Field Conditions

Soluble salts above a critical limit produce harmful effects to plant growth. It may be either due to increased osmotic pressure of the soil solution or unavailability of water. Plant growth is also depressed when the soil is highly saturated with exchangeable sodium or by the toxicity of some specific ion like boron. The degree to which a plant can resist salinity, alkalinity or toxicity of boron is a characteristic property of a crop or its varieties. This property of the crop is generally kept in mind while selecting crops for growing under saline-alkali conditions. Salt tolerance property of crops has been found very useful in overcoming the hazardous effect of salts on plant growth and yield has been successfully utilised in managing arid and semiarid areas of western countries. Differences between species and varieties regarding salt tolerance have been reported by Ayers et al (1952), Richard (1954), Bernstein and Hayward (1958) and Hayward and Bernstein (1958). Similar information on agricultural crops in India is not available in relation to the severity and magnitude of the problem. Only recently some work on these lines has been reported by Desai et al (1957), Mehta and Desai (1959), Mehrotra and Gangwar (1964), Asana and Kale (1965) and Maliwal and Paliwal (1966). Most of the results on salt tolerance of crops are based on either germination or pot culture studies. It is, therefore, proposed to examine the effect of saline-alkali conditions on the growth of wheat and gram in the natural environment of the fields, and also to find out their limits of salinity, alkalinity and boron tolerance.