Inoculating wheat seedlings with exopolysaccharide-producing bacteria restricts sodium uptake and stimulates plant growth under salt stress     

Muhammad?Ashraf  Shahida?Hasnain  Odile?Berge  Tariq?MahmoodEmail author 《Biology and Fertility of Soils》2004,40(3):157-162

A pot experiment was conducted to elucidate the effects of inoculating five exopolysaccharide- (EPS-) producing bacterial strains on the dry matter yield and the uptake of K⁺, Na⁺, and Ca²⁺ by wheat seedlings grown in a moderately saline soil. The bacteria were isolated from the rhizosphere soil (RS) of wheat grown in a salt-affected soil and included Aeromonas hydrophila/caviae (strain MAS-765), Bacillus insolitus (strain MAS17), and Bacillus sp. (strains MAS617, MAS620 and MAS820). The inoculation substantially increased the dry matter yield of roots (149–527% increase) and shoots (85–281% increase), and the mass of RS (176–790% increase). All the strains, except MAS617, also increased the RS mass/root mass ratio as well as the population density of EPS bacteria on the rhizoplane, and both these parameters were significantly correlated with the content of water-insoluble saccharides in the RS. Inoculation restricted Na⁺ uptake by roots, which was not attributable to the binding of Na⁺ by the RS, or to the ameliorative effects of Ca²⁺ under salinity. The decreased Na⁺ uptake by roots of inoculated than uninoculated plants was probably caused by a reduced passive (apoplasmic) flow of Na⁺ into the stele due to the higher proportion of the root zones covered with soil sheaths in inoculated treatments. Among the strains tested, MAS820 was the most efficient in all respects, whereas MAS617 was the least effective. Results suggested that inoculating selected EPS-producing bacteria could serve as a useful tool for alleviating salinity stress in salt-sensitive plants.  相似文献   

Improving Strategic Growth Stage-based Drought Tolerance in Quinoa by Rhizobacterial Inoculation     

Muhammad Usman Aslam  Muhammad Farrukh Saleem  Muhammad Waqas  Rashid Iqbal  Salman Ahmad 《Communications in Soil Science and Plant Analysis》2020,51(7):853-868

ABSTRACT

Climate change is imposing high temperature resulting in prolonged drought episodes and shrinking of fresh water resources across the globe. In this scenario, even drought tolerant crops like quinoa are also losing significant yield. However, this study was planned to investigate the impact of drought on quinoa at critical growth stages and bacterial inoculation to improve drought tolerance. Drought was imposed by maintaining 25% pot water holding capacity (PWC) at multiple leaf, flowering, and seed filling stage (DSFS), while 80% PWC was considered as control. Three strains of plant growth promoting rhizobacteria (PGPR) named as: Bacillus licheniformis, Pseudomonas fluorescens, and Azospirillum brasilense were inoculated with quinoa seeds before sowing with respect to drought treatments. PGPR inoculation mitigated the drastic effects of drought by improving crop growth, net assimilation rate, water use efficiency, leaf chlorophyll, and phenolic contents, all of these ultimately contributed to improvement in grain yield and its contributing attributes. Moreover, PGPR markedly improves the grain quality attributes including protein, phosphorus, and potassium contents. Principal component analysis linked the different scales of study and demonstrated the potential of physio-biochemical traits to explain the quinoa yield variations under drought condition with response to PGPR inoculation. Among different PGPR, A. brasilense was found most effective both under normal and drought conditions. Overall, DSFS has more detrimental effects among critical growth stages of quinoa and A. brasilense can be used as a shotgun tactic to ameliorate drought stress in quinoa.  相似文献   

Synergistic effects of the inoculation with nitrogen‐fixing and phosphate‐solubilizing rhizobacteria on the performance of field‐grown chickpea     

Parvaze A. Wani  Mohammad Saghir Khan  Almas Zaidi 《植物养料与土壤学杂志》2007,170(2):283-287

The synergistic effects of nitrogen‐fixing and phosphate‐solubilizing rhizobacteria on plant growth, yield, grain protein, and nutrient uptake of chickpea plants were determined in a sandy clay‐loam soil. Legume grain yield and concentration and uptake of nitrogen (N) and phosphorus (P) were significantly increased as a result of co‐inoculation with Mesorhizobium and P‐solubilizing Pseudomonas and Bacillus spp. The inoculation with M. ciceri RC4 + A. chroococuum A10 + Bacillus PSB9 tripled the seed yield and resulted in highest grain protein (295 mg g^–1) at 145 d after sowing (DAS). An 8% increase in P concentration above the uninoculated control was observed in case of a single inoculation with Pseudomonas PSB 5, while the P uptake was highest (2.14‐fold above the uninoculated control) with a combined inoculation with [M. ciceri RC4 + A. chroococcum A10 + Bacillus PSB 9] at 145 DAS. The highest N concentration and N uptake at 145 DAS (81% and 16% above the uninoculated control, respectively) were observed with the triple inoculation of [M. ciceri RC4 + A. chroococcum A10 + Pseudomonas PSB 5). These findings show that multiple inoculations with rhizospheric microorganisms can promote plant growth and grain yield and increase concentrations and uptake of N and P by field‐grown chickpea.  相似文献   

OPTIMUM DESIGN OF SEDIMENTATION TANKS BASED ON SETTLING CHARACTERISTICS OF KARACHI TANNERY WASTES     

Akhtar  Waseem  Rauf  Muhammad  Ali  Iqbal  Nayeemuddin 《Water, air, and soil pollution》1997,98(3-4):199-211

A study was carried out in a specially designed settling column to investigate the settling characteristics of effluents arising from Karachi tanneries. The Jar-tests were conducted to determine the optimum dosage of coagulants such as potash alum and ferric chloride to maximize the removal of suspended solids (S.S) from the wastes. For alum, the optimum dosage was found to be 150 mg L^-1, whereas with ferric chloride it was 30 mg L^-1. Experiments carried out in the settling column with the optimum coagulant dosages showed that the coagulation with ferric chloride was much better than with alum, as it removes about 84% S.S from the wastes compared to 70% removal obtained in case of alum. Design curves in terms of percent removal of S.S. vs loading rate and detention time were constructed using data obtained from settling column. These curves can be used in designing the settling tanks employed in the tannery wastes treatment plants.  相似文献   

Silicon fertilization – A tool to boost up drought tolerance in wheat (Triticum aestivum L.) crop for better yield     

Munir Ahmad  Mohamed H. El-Saeid  Muhammad Abrar Akram  H. R. Ahmad  Haseeb Haroon  Abid Hussain 《Journal of plant nutrition》2016,39(9):1283-1291

In this study, impact of silicon (Si) application on wheat performance under drought stress is studied. Experimental soil was sandy clay loam with an average pH of 8.01, electrical conductivity (EC) of 2.36 dSm^?1, and calcium carbonate (CaCO₃) content of 2.16%. Soil was severely deficient in organic matter (<1%). Average extractable phosphorus (P) and potassium (K) concentration was 230 and 5.21 mg kg^?1, respectively. Silicon potassium metasilicate (K₂SiO₃) was applied at the rate of 0 and 12 kg/ha with three canal water irrigation frequencies including two, three, and four under randomized complete block design (RCBD) factorial fashion with three replications. Results indicated that drought stress significantly reduced plant height, spike length, shoot fresh weight, and number of spikelets/spike, eventually enhancing wheat yield. Concentration of K⁺ in shoot (28.65 mg g^?1) and grains (3.51 mg g^?1) increased with Si application, which helped to maintain water potential in plant even under reduced moisture level in plants and soil, ultimately producing more yield and biomass under drought stress conditions.  相似文献   

2-Keto-4-methylthiobutyric acid-dependent biosynthesis of ethylene in soil   总被引：5，自引：0，他引：5  

Zill-i-Huma?Nazli  Muhammad?ArshadEmail author  Azeem?Khalid 《Biology and Fertility of Soils》2003,37(2):130-135

2-Keto-4-methylthiobutyric acid (KMBA) has been identified as an intermediate in methionine-derived ethylene (C₂H₄) biosynthesis by microbial cultures. This study was designed to assess the effectiveness of KMBA as an C₂H₄ precursor in soil. Gas chromatographic analysis indicated that amendment with KMBA (up to 10 mM) stimulated the biosynthesis of C₂H₄ in two Pakistani soils. Results also revealed that substrate- (KMBA)-dependent C₂H₄ production was inhibited when the soils were amended either with glucose (as a C source), NH₄NO₃ (N source) or antibiotics. The KMBA-derived C₂H₄ biosynthesis in both soils was maximum when the soil suspension was amended with 10 mM substrate and incubated at pH 7.5 for a period of 120 h at 35°C with shaking. Comparison of soils revealed that C₂H₄ production was relatively greater in a silty clay loam S₁ (containing 1.15% organic C) soil compared to a loamy S₂ (containing 0.54% organic C) soil. KMBA was found to be an equally effective substrate of C₂H₄ when compared with another intermediate, 1-aminocyclopropane-1-carboxylic acid (ACC), whereas, f-ketglutaric acid failed to serve as an C₂H₄ substrate in soil. As far as we know, this is the first study reporting KMBA-dependent C₂H₄ production in soil.  相似文献   

Substrate-dependent biosynthesis of ethylene by rhizosphere soil fungi and its influence on etiolated pea seedlings   总被引：1，自引：2，他引：1  

Muhammad J. Akhtar  Muhammad Arshad  Azeem Khalid  Muhammad H. Mahmood 《Pedobiologia》2005,49(3):211-219

Several fungi were isolated from rhizosphere soils of various crops through enrichment on l-methionine (l-MET) as a sole C and N source. These fungi were examined for their C₂H₄ production potential in vitro. GC-FID analysis indicated that 78%, 83%, 89% and 72% of fungi isolated from rhizosphere soil of wheat, maize, potato and tomato, respectively, produced C₂H₄ from substrate l-MET. Eight of the most efficient C₂H₄-producing fungal isolates (two from each crop) were further tested for their ability to produce C₂H₄ from 2-keto-4-methylthiobutyric acid (KMBA) and α-ketoglutaric acid (α-KGA). Interestingly, all eight fungi produced C₂H₄ from KMBA, but none used α-KGA as C₂H₄ precursor. This result implies that the MET→KMBA→C₂H₄ pathway was most likely operating in these fungi. The most efficient C₂H₄ producer fungus (isolated from maize rhizosphere soil) was identified as Aspergillus terreus; this isolate was further studied to determine the optimal conditions for C₂H₄ production from l-MET. It was observed that a substrate (l-MET) concentration of 10 mmol l⁻¹, a glucose (C-source) concentration of 6.0 g L⁻¹, no nitrogen, a pH of 6.0, an incubation temperature of 30 °C and an incubation time of 72 h were optimal conditions for l-MET-derived C₂H₄ biosynthesis by Aspergillus terreus. In addition, C₂H₄ released from precursor (l-MET) by Aspergillus terreus significantly affected the seedling length and stem diameter of etiolated pea seedlings in both sterilized and non-sterilized soils compared to a control. C₂H₄-producing microflora may be ubiquitous in soil, and the availability of a substrate like l-MET could enhance C₂H₄ synthesis in the rhizosphere of a plant, in turn evoking a physiological response. As far as we know, this study represents the first comprehensive screening of rhizosphere fungi for their ability to produce C₂H₄ from l-MET and KMBA.  相似文献   

Isolation and characterization of polyphenol type-A polymers from cinnamon with insulin-like biological activity   总被引：10，自引：0，他引：10  

Anderson RA  Broadhurst CL  Polansky MM  Schmidt WF  Khan A  Flanagan VP  Schoene NW  Graves DJ 《Journal of agricultural and food chemistry》2004,52(1):65-70

The causes and control of type 2 diabetes mellitus are not clear, but there is strong evidence that dietary factors are involved in its regulation and prevention. We have shown that extracts from cinnamon enhance the activity of insulin. The objective of this study was to isolate and characterize insulin-enhancing complexes from cinnamon that may be involved in the alleviation or possible prevention and control of glucose intolerance and diabetes. Water-soluble polyphenol polymers from cinnamon that increase insulin-dependent in vitro glucose metabolism roughly 20-fold and display antioxidant activity were isolated and characterized by nuclear magnetic resonance and mass spectroscopy. The polymers were composed of monomeric units with a molecular mass of 288. Two trimers with a molecular mass of 864 and a tetramer with a mass of 1152 were isolated. Their protonated molecular masses indicated that they are A type doubly linked procyanidin oligomers of the catechins and/or epicatechins. These polyphenolic polymers found in cinnamon may function as antioxidants, potentiate insulin action, and may be beneficial in the control of glucose intolerance and diabetes.  相似文献   

Determination of diquat and paraquat residues in soil by gas chromatography     

S U Khan 《Journal of agricultural and food chemistry》1974,22(5):863-867

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Biologically active secondary metabolites from Ginkgo biloba     

Bedir E  Tatli II  Khan RA  Zhao J  Takamatsu S  Walker LA  Goldman P  Khan IA 《Journal of agricultural and food chemistry》2002,50(11):3150-3155

Three new compounds, (7E)-2beta,3alpha-dihydroxy-megastigm-7-en-9-one (1), 3-[5,7-dihydroxy-2-(4-methoxyphenyl)-4-oxo-4H-chromen-8-yl]-4-methoxybenzoic acid (2), and 4'-O-methyl myricetin 3-O-(6-O-alpha-L-rhamnopyranosyl)-beta-D-glucopyranoside (3), were isolated from Ginkgo biloba, together with 27 known compounds. The structures of the new compounds were determined primarily from 1D- and 2D-NMR analysis. The 4-O-methylbenzoic acid structural feature at C-8 in 2 is encountered for the first time. The antioxidant activities of 29 compounds isolated from Ginkgo biloba were evaluated on intracellular reactive oxygen species in HL-60 cells. It was found that quercetin, kampferol, and tamarixetin had antioxidant activity that was approximately 3-fold greater than that of their respective glycosides and also approximately 3-fold greater than that of a standard ascorbic acid with an IC(50) at maximum effectiveness.  相似文献