Browsing by Author "Surendra Singh"

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A new insight into the commercial applications of halotolerant green algae Dunaliella
(Nova Science Publishers, Inc., 2018) Pradeep Kumar Rai; Anuradha Rai; Surendra Singh
Recently, the cultivation of microalgae as a renewable source of fuel and energy has been receiving much attention globally. Dunaliella is probably the most halotolerant and dominant photosynthetic eukaryote that thrives in most natural and artificial hypersaline niches occupied almost exclusively by halophilic archaebacteria. This alga is cultivated commercially as a source of many valuable macromolecules such as proteins, lipids and pigments. It is one of the best sources for the commercial production of carotene, glycerol and protein. Different species of Dunaliella have the ability to produce a wide variety of high-value bioactive compounds, fine biochemicals, and bulk compounds such as lipids, pigments, natural dyes and biomass. The ability to grow at high salt concentrations coupled with the production of high amount of β-carotene, glycerol and protein have made this microalga an attractive candidate for commercial application in medicine, the food industry and agriculture. © 2018 by Nova Science Publishers, Inc. All rights reserved.
A Thorough Comprehension of Host Endophytic Interaction Entailing the Biospherical Benefits: A Metabolomic Perspective
(Springer Science and Business Media B.V., 2019) Shatrupa Ray; Jyoti Singh; Rahul Singh Rajput; Smriti Yadav; Surendra Singh; Harikesh Bahadur Singh
Endophytism is the phenomenon of in planta residency and mutualistic association of microbes with hosts without causing any disease symptoms. The multifaceted attributes of endophytes include plant growth promotion as well as resistance of the host to several forms of abiotic or biotic stresses. Moreover, endophytes are reported to manipulate the rhizospheric microbiota as well as the microbiota present within plants so as to amplify the host beneficial mechanisms. Endophyte mediated host beneficial traits become far more significant owing to the differential recruitment of endophytes by host under varying root exudate profile, host’s age, as well as host-endophyte compatibility. However, in spite of such beneficial attributes, our understanding of endophytes is still quite limited and inadequate. Thus, the true potential of endophytes can be particularly harnessed when we gain a thorough insight on the molecular mechanisms responsible for mutualistic host-endophyte interaction. In this chapter, we present an exhaustive investigation of endophyte-plant interaction, beginning from chemotactic attraction of the supposed endophytic microflora from soil to establishment of endophytism. We will also focus on the endophyte-directed metabolite biosynthesis aiding in effective host functioning. © 2019, Springer Nature Switzerland AG.
Addition of Crop Residues with Different C:N Ratios on the Release Pattern of Available Nitrogen and Sulfur in Different Soils
(Taylor and Francis Ltd., 2021) Sreejan Singh; P.K. Sharma; Surendra Singh; Arvind Kumar
Mineralization of organic N and S of crop residue is an important useful tool for forecasting availability of N and S in soils. Three different soils (Vertisol, Inceptisol and Alfisol) from eastern Uttar Pradesh, India; seven crops residue, four cereals (rice, barley, maize, wheat) from irrigated area of Varanasi; and three pulses (gram lentil, pigeon pea) from rainfed area of Mirzapur were used in 90-day incubation study under controlled condition to estimate the release of soil available N and S. The experiment was laid out in a factorial completely randomized design with three replications. Total Nitrogen (N) and total Sulfur (S) contents were higher in the pulses than that of cereals. Pulses residue with the lowest C:N:S ratio (177.0:3.7:1 to 195.8:4.5:1) had significantly rapid rate of N and S release up to 45 days and then declined at 60 and 90 days. On the other hand, cereals with the highest C:N:S ratio (390.8:4.3:1 to 463.6:5.0:1) had slow release of N and S up to 45 days and then rapid released at 60 and 90 days. Among pulses residue, pigeon pea has resulted significantly higher net release of soil available N and S at day 45 to the extent of 18.4 and 78.7% in Alfisol, 17.7 and 51.2% in Inceptisol, and 15.0 and 24.1% in Vertisol, respectively, over control. Among the cereals residue, barley residue amended Alfisol had higher net increase in available N at day 90 (13.2%) followed by Inceptisol (10.8%) and Vertisol (9.9%) over control. © 2021 Taylor & Francis Group, LLC.
Airborne algae: Their present status and relevance
(2007) Naveen Kumar Sharma; Ashwani Kumar Rai; Surendra Singh; Richard Malcolm Brown Jr.
Ongoing climatic changes coupled with various natural processes and the outcomes of human activities are not only loading the atmosphere with diverse kinds of biological particles but also changing their prevalence and spatial distribution. Despite having considerable ecological and economic significance, including their possible impact on human health, airborne algae are the least-studied organisms in both aerobiological and phycological studies. The present review has been written to bring together all available information, including a brief survey of the literature, the ecology of airborne algae, mechanisms involved in their aerosolization, the role of environmental factors in shaping the structure and composition of aero-algal flora, and other significant information associated with airborne algae. This review provides information on methodological approaches and related problems, along with suggestions for areas of future research on airborne algae. © 2007 Phycological Society of America.
An assessment of soil available nutrients status of chunar area in mirzapur district of eastern uttar pradesh
(Indian journals, 2020) Lalit Pandey; Amit Prajapati; Surendra Singh; Sreejan Singh
Present investigation was conducted to assess the physicochemical properties as well as available nutrients status of alluvial soils of Chunar area in Naryanpur block of Mirzapur district of eastern part of Uttar Pradesh. Naryanpur block has total net sown area of 17376 hectares. Altogether, ninety-eight surface soil samples were collected from the farmer’s field of Chunar area covering eleven villages. The analysis of the soil samples revealed that majority of the soil samples fall under sandy clay loam to sandy loam. The soils were slightly acidic to moderately alkaline in reaction ranging from pH 6.3-8.9 with a mean pH value of 8.03. The electrical conductivity (EC) value ranged from 0.12 to 0.89 dS m-1 with a mean value of 0.30 dS m-1. Mean value of organic carbon (OC) was 4.6 g kg-1 and varied from 1.6-12.7 g kg-1, CaCO3 content varied from 0.08 to 3.4% with mean value of 1.05%. Mean values for nitrogen (N), phosphorus (P) and potassium (K) as obtained from the analysis were 229, 24.4, 232 kg ha-1, respectively. Overall, mean values for exchangeable Ca and Mg and available S were 14.5, 3.84 cmol(p+)kg-1 and 10.7 mg kg-1, respectively. The mean values for available Cu, Mn, Fe, Zn and B were 0.74, 4.99, 20.8, 0.85 and 0.43 mg kg-1, respectively. Available N, S and B were rated to be low in soils. Hence, there is need to supply these deficient nutrients through external organic and inorganic sources for sustaining crop productivity and soil health of Chunar area in Narayanpur block of Mirzapur district of eastern Uttar Pradesh. © 2020, Indian journals. All rights reserved.
An Overview of Micronutrients: Prospects and Implication in Crop Production
(Springer International Publishing, 2020) Hanuman Singh Jatav; L. Devarishi Sharma; Rahul Sadhukhan; Satish Kumar Singh; Surendra Singh; Vishnu D. Rajput; Manoj Parihar; Surendra Singh Jatav; Dinesh Jinger; Sunil Kumar; Sukirtee
Micronutrients are important for plant growth and they significantly play an important role in balanced crop nutrition. They are vital for appropriate growth and development of plants in their entire life span. A deficiency of any one of the micronutrients in the soil can limit the growth of plants, even when all other nutrients are available in adequate amounts. The deficiency of micronutrients is widespread in many areas due to the nature of soils, high pH, low organic matter, salt stress, continuous drought, high bicarbonate content in irrigation water and imbalanced application of fertilisers. In India, the most deficient micronutrient in the soil is Zn, followed by B. In recent years, the deficiency of micronutrient has risen to a great extent. Zn and B deficiencies are focussed mainly for their adverse impacts on human health and food production. This chapter attempts to examine the defects of Zn, Fe, Mn, Cu, B and Mo deficiency in the soil and crops as well as the management of micronutrient deficiencies by way of fertilisation, development of agronomic strategies and creation of awareness of micronutrient dose. Deficiencies of Zn and B cause some severe complications in crop production in India. In view of the problems, we discuss the importance of micronutrients in agriculture and their roles and ways to improve crop productivity. © Springer Nature Switzerland AG 2020.
Antioxidant Potentiality and Mineral Content of Summer Season Leafy Greens: Comparison at Mature and Microgreen Stages Using Chemometric
(Springer, 2019) Lalu Prasad Yadav; Tanmay Kumar Koley; Ajay Tripathi; Surendra Singh
Nine summer season leafy greens viz., Amaranthus, bottle gourd, cucumber, jute, palak, poi, pumpkin, radish, water spinach, were evaluated for their antioxidants and mineral content at microgreen and mature stages. Among the antioxidants, total phenolics, total flavonoids, and ascorbic acid were quantified. Besides, antioxidant activities of the leafy vegetables were also measured using four in vitro assays viz., ferric reducing antioxidant power (FRAP), cupric reducing antioxidant power (CUPRAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and Trolox equivalent antioxidant capacity assays (TEAC). In addition to this, the content of selected elements such as potassium (K), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) was estimated. A wide variation was observed in the content of antioxidants and minerals. Variation was also observed for cultivar to cultivar as in case of Amaranthus. Results showed that the total phenolic content varied from 95.73 to 313.92 mg Gallic acid equivalent (GAE)/100 g in the mature vegetables, whereas the value varied from 25.00 to 152.10 mg GAE/100 g in microgreens. In fact, mature leafy vegetables were found to be significantly higher sources for total phenolics than microgreens. Likewise, a similar trend was observed for total flavonoids content and antioxidant activities. On the contrary, in all the species the concentration of K and Zn was significantly higher in microgreens than mature vegetables. However, no specific trend was observed in case of Fe, Cu, and Mn content. Based on antioxidant potentiality and mineral content, these leafy greens formed three distinct clusters; the first cluster represented by Amaranthus cv Local Green, jute, bottle gourd, and water spinach at mature stages. Jute was found to be the best, followed by bottle gourd, Amaranthus cv. Local Green, and water spinach. © 2018, NAAS (National Academy of Agricultural Sciences).
Arsenic contamination-a societal issue
(2013) Ishwar Chandra Yadav; Surendra Singh
[No abstract available]
Assessment of groundwater quality with special reference to arsenic in Nawalparasi district, Nepal using multivariate statistical techniques
(Springer Verlag, 2014) Ishwar Chandra Yadav; Ningombam Linthoingambi Devi; Devendra Mohan; Qi Shihua; Surendra Singh
Groundwater is a precious resource for humankind not only in Nepal but also across the globe due to its diverse functions. A total of 48 groundwater samples were collected from three villages of Nawalparasi district, Nepal, during pre-monsoon and monsoon to estimate the overall groundwater quality and to identify the sources of contamination with emphasis on arsenic (As). The average concentrations of all tested groundwater quality parameters (temp., pH, EC, ORP, Ca2+, Mg2+, Na+, K+, Cl-, F-,SO4 2-, PO4 3-, HCO3 -, NO3 -, Cu, Ni, Mn, Cd, Pb, Fe, Zn, Cr, and As) were well within permissible limits of WHO for drinking water, except for Ni, Cd, Pb, Cr, and As. Concentration of As ranged from 60 to 3,100 μg L-1 and 155 to 1,338 μg L-1 in pre-monsoon and monsoon, respectively. The Piper diagram of the groundwater chemistry showed groundwater of Nawalparasi belongs to Ca-Mg-HCO3 and Mg-HCO3 water type with HCO3 - as dominant ions. As content in the study area was negatively correlated with Fe in pre-monsoon, while it was positively correlated in monsoon. Furthermore, As was negatively correlated with oxidation reduction potential suggesting reducing condition of groundwater. Principal component analysis revealed seven major factors that explained 81.996 and 83.763 % of total variance in water quality in pre-monsoon and monsoon, respectively. The variance of water quality was related mainly with the degree of water-rock interaction, mineralization, and anthropogenic inputs. © 2013 Springer-Verlag Berlin Heidelberg.
Available nutrients status and response of wheat (Triticum aestium L.) to sulphur and zinc application in inceptisols of Varanasi
(IndianJournals.com, 2018) Surendra Singh
[No abstract available]
Biochemical and histochemical analyses revealing endophytic Alcaligenes faecalis mediated suppression of oxidative stress in Abelmoschus esculentus challenged with Sclerotium rolfsii
(Elsevier Masson SAS, 2016) Shatrupa Ray; Vivek Singh; Surendra Singh; Birinchi Kumar Sarma; Harikesh Bahadur Singh
Sclerotium rolfsii is a highly aggressive pathogen that causes huge economic losses, especially in temperate climates. Alcaligenes faecalis, particularly in endophytic form, has rarely been used to control this fungus. In this study, endophytic Alcaligenes sp. strain BHU 12, BHU 16 (isolated from Abelmoschus esculentus leaf) and BHU M7 (isolated from Andrographis paniculata leaf) were reported to trigger a wide range of host defenses in Okra plant against the collar-rot pathogen S. rolfsii. Endophytic colonization of the strains in ten days old plants was assessed through re-isolation of the rif-tagged strains on rifampicin augmented nutrient agar media. The ability of the endophytic strains to induce systemic defense responses in above-ground organs was assessed by collecting leaf tissues of the Okra plants grown under non-gnotobiotic conditions at different time intervals post seedling bacterization with the endophytic biocontrol agents. The pathogen challenged unprimed plants exhibited flaccidity of the stem and leaves at 48 h post infection (hpi) in contrast to the bioprimed and challenged plants. Biochemical and histochemical analyses explained the above phenomenon as activation of phyto-peroxidases leading to an increased metabolism of the reactive oxygen species (ROS), accompanied by activation of the phenylpropanoid network and a subsequent enhancement in plant phenolics. Interestingly, though the maximum increase in the defense pathways was observed in treatments with native endophytes of Okra plant, yet the enhancement in antioxidant pathway due to A. paniculata borne endophytes was also quite significant. Thus, this work clearly demonstrates how Okra plants respond to the “non-hostile” colonization of bacterial endophytes and how induced defense response can contribute to the biocontrol activity of the endophytic strains. © 2016 Elsevier Masson SAS
Biocontrol agents-mediated suppression of oxalic acid induced cell death during Sclerotinia sclerotiorum-pea interaction
(Wiley-VCH Verlag, 2015) Akansha Jain; Akanksha Singh; Surendra Singh; Birinchi Kumar Sarma; Harikesh Bahadur Singh
Oxalic acid (OA) is an important pathogenic factor during early Sclerotinia sclerotiorum-host interaction and might work by reducing hydrogen peroxide production (H2O2). In the present investigation, oxalic acid-induced cell death in pea was studied. Pea plants treated with biocontrol agents (BCAs) viz., Pseudomonas aeruginosa PJHU15, Bacillus subtilis BHHU100, and Trichoderma harzianum TNHU27 either singly and/or in consortium acted on S. sclerotiorum indirectly by enabling plants to inhibit the OA-mediated suppression of oxidative burst via induction of H2O2. Our results showed that BCA treated plants upon treatment with culture filtrate of the pathogen, conferred the resistance via. significantly decreasing relative cell death of pea against S. sclerotiorum compared to control plants without BCA treatment but treated with the culture filtrate of the pathogen. The results obtained from the present study indicate that the microbes especially in consortia play significant role in protection against S. sclerotiorum by modulating oxidative burst and partially enhancing tolerance by increasing the H2O2 generation, which is otherwise suppressed by OA produced by the pathogen. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Biological management of Sclerotinia sclerotiorum in pea using plant growth promoting microbial consortium
(Wiley-VCH Verlag, 2015) Akansha Jain; Akanksha Singh; Surendra Singh; Harikesh Bahadur Singh
The beneficial plant-microbe interactions play crucial roles in protection against large number of plant pathogens causing disease. The present study aims to investigate the growth promoting traits induced by beneficial microbes namely Pseudomonas aeruginosa PJHU15, Trichoderma harzianum TNHU27, and Bacillus subtilis BHHU100 treated singly and in combinations under greenhouse and field conditions to control Sclerotinia sclerotiorum. Plants treated with three microbe consortium enhanced plant growth maximally both in the presence and absence of the pathogen. Increase in plant length, total biomass, number of leaves, nodules and secondary roots, total chlorophyll and carotenoid content, and yield were recorded in plants treated with microbial consortia. Also, a decrease in plant mortality was observed in plants treated with microbial consortia in comparison to untreated control plants challenged with S. sclerotiorum. Furthermore, the decrease in disease of all the treatments can be associated with differential improvement of growth induced in pea. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Biotic stress management in agricultural crops using microbial consortium
(Springer-Verlag Berlin Heidelberg, 2013) Akansha Jain; Akanksha Singh; Brahma N. Singh; Surendra Singh; R.S. Upadhyay; B.K. Sarma; H.B. Singh
Microbial populations have functional roles within communities where interactions among distinct microorganisms will permit their survival. Therefore, it is suggested to device mixed inoculants that may interact synergistically, with different or complementary mode of action, so that increased disease resistance is provided and under certain stresses we can assume that atleast one is functional. The mechanisms responsible for this biocontrol activity include competition for nutrients, niche exclusion, induced systemic resistance (ISR), and the production of anti-microbial metabolites. Therefore, seeing the success stories of mixed inoculants (combination of microorganisms that interact synergistically) over single bioinoculant, consortiums are being currently devised for crop management. The extreme complexity of interactions occurring is highlighted, and some potential areas and shortcomings required to overcome for future researches in this area are discussed briefly. © Springer-Verlag Berlin Heidelberg 2013. All rights are reserved.
Change in soil microbial biomass along a rural-urban gradient in Varanasi (U.P., India)
(UBM Exhibition Singapore PTE LTD, 2018) Pradeep Kumar Rai; Anuradha Rai; Surendra Singh
Soil microbial biomass has been used as an early indicator of change in soil properties resulting from urbanization. We analyzed the effect of urbanization along a rural–urban gradient on soil microbial biomass and physico-chemical properties of the soil. The mean microbial biomass carbon (MBC) value were 107.4, 121.3, and 134.2 μg g−1 of soil, respectively, for urban, sub-urban and rural sections of the gradient. Whereas, the mean microbial biomass nitrogen (MBN) was 10.2, 11.5, and 12.5 μg g−1 of soil for urban, sub-urban, and rural gradient. Similarly, the mean values of microbial biomass phosphorus (MBP) were 5.1, 5.8, and 6.3 μg g−1 of soil, for urban, sub-urban, and rural gradient, respectively. ANOVA and Tukey’s Honest Significant Difference (HSD) analyses showed significant difference (P ≤ 0.05) in microbial biomass with physico-chemical characteristics of soils. Maximal soil microbial biomass was reported for rural soils followed by sub-urban and urban soil. Disturbance in soil texture, increased in BD and decrease in soil moisture content as major factors responsible for depletion in soil microbial biomass in urban soils. Thus, suggesting that the urbanization adversely effected soil microbial biomass by altering natural soil characteristics. © 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
Changes in photoelectron transport activity in cyanophage N-1-infected cells of Nostoc muscorum
(Springer-Verlag, 1989) A.K. Kashyap; Surendra Singh
Cyanophage N-1-infected Nostoc muscorum cells were unable to carry out oxygen evolution and photosystem-II-dependent electron transport (H2O→DCPIP). This was associated with preferential degradation of phycobiliproteins. Such cells also exhibited decreased rate of ferredoxin:NADP+ oxidoreductase activity. However, Ca2+-dependent ATPase activity was maintained at a higher level (80%). The results suggested that virus development proceeds in the absence of photosystem-II activity, and the energy is provided by cyclic photophosphorylation aside from that possibly obtained via degradation of carbohydrate reserves. © 1989 Springer-Verlag New York Inc.
Changes in Water Soluble Protein Profile of Antarctic Cyanobacterium Nostoc Commune under Temperature Downshift from 25° to 5 °C
(Taylor and Francis Inc., 2019) Ranjana Tripathi; Pradeep Kumar Rai; Anuradha Rai; Surendra Singh
The cyanobacterium Nostoc commune (Nostocales) is an isolate from the Schirmacher Oasis Antarctica. The cyanobacterium is psychrotropic in nature; and maintained in laboratory at 25 °C temperature, in unialgal form. Here, we studied the change in protein profile of water soluble proteins from exponentially growing N. commune upon downshift from its optimum growth temperature (25 °C) to a low temperature (5 °C). Experimental set up used to analyze the proteome were- a sudden shift to low temperature (i.e., cold shock), after short- (8 days) and long-term acclimation (7 weeks) to low temperature (5 °C). Cold-shock resulted in an increase in Low molecular weight proteins (LMWPs) with clouding of diffused proteins. Further increase in the duration of incubation period (short- and long-term acclimation) caused dissociation of proteins, indicated by NaCl (50–600mM) induced dissociation of proteins. That is, high molecular weight proteins (HMWPs) dissociated into LMWPs resulting in an increased number of protein bands. This was further confirmed by addition of LMWPs (≤10KDa) resulting in re-association of proteins into HMWPs. Hence, we report that the cold-induced synthesis of LMWPs (≤10kDa) is a strategy adopted by the N. commune to survive at low temperature of Antarctica. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.
Characterization of NaCL-tolerant mutant strain of the cyanobacterium Spirulina platensis overproducing phycocyanin
(Bentham Science Publishers B.V., 2017) Apurva Gupta; Surendra Singh
Background: Spirulina spp., a promising source of phycocyanin, is commercially grown in open ponds and raceways photoautotrophically. However, the economic exploitation in an open system seems to have been limited because of lack of multiple stress-tolerant strains. Methods: In order to have an improved production of phycocyanin, a NaCl tolerant mutant of the cyanobacterium Spirulina platensis was isolated using a chemical mutagen, N-methyl-N′-nitro-Nnitrosoguanidine (NTG) and selection for NaCl tolerant strain. Results: The mutant strain exhibited improved growth and overproduced phycocyanin at 0.8 M NaCl. NaCl-tolerant mutant also exhibited higher rate of photosynthesis and reduced rate of respiration in response to 0.8 M NaCl. The mutant strain took up more nitrate and reduced it more effectively in presence of NaCl which explains its enhanced phycocyanin accumulatory behavior. The mutant strain also protected its cells from NaCl stress by accumulating low amounts of trehalose, glucosyl-glycerol and proline, and by synthesizing anti-oxidative enzymes in comparison to wild type strain which further supports the subdued effects of NaCl and halotolerant behavior of mutant strain. Conclusion: The NaCl tolerant mutant synthesized 1.5 folds higher phycocyanin as compared to wild type in response to 0.8 M NaCl. The mutant strain clearly demonstrates unique haloprotective strategies that mitigate the deleterious effects of high NaCl concentration as reflected by its efficient photosynthesis and nitrogen metabolism. Moreover, the subdued defense response of mutant in relation to osmolytes accumulation and antioxidant enzymes confirms its adaptive and tolerant behavior against NaCl. © 2017 Bentham Science Publishers.
Characterization of phosphate solubilizing fluorescent pseudomonads from the rhizosphere of Aloe vera (L.)
(Taylor and Francis Ltd., 2018) Anuradha Rai; Pradeep Kumar Rai; Surendra Singh
Soil phosphorous (P) deficiency is a major constraint to plant production which is overcome by adding inorganic-phosphate as chemical fertilizers. Fluorescent pseudomonads are the diverse group of bacteria able to mobilize sparingly soluble phosphate form. Total three hundred seven fluorescent Pseudomonas isolates were obtained from the Aloe barbadensis (Miller) rhizosphere. These Pseudomonas strains were further evaluated in vitro for their ability to solubilize phosphate and to produce indole acetic acid (IAA), hydrogen cyanide (HCN), siderophore and 1-aminocyclopropane 1- carboxylate (ACC) deaminase. Fifty three (36.8%) isolates produced IAA and 52 (36.1%) isolates produced siderophores whereas 36 (25.0%) and 31 (21.5%) isolates produced HCN and ACC deaminase, respectively. A positive correlation existed between siderophore and ACC deaminase producers. Cluster analysis showed rhizosphere as the major factor influencing the ecological distribution and physiological characterization of phosphate solubilizing bacteria (PSB). Based on partial 16S rRNA gene sequencing PSB were identified as Pseudomonas putida, Pseudomonas sp. and Pseudomonas plecoglossicida with highest phosphate solubilization ability. In conclusion, these phosphate solubilizing fluorescent pseudomonads would help in understanding their role in phosphorus solubilization and identification of potent phosphorus solubilizers from the rhizosphere of commercially grown A. barbadensis. © 2017 Informa UK Limited, trading as Taylor & Francis Group.
Chemical shift and donor-electron radius for lightly doped n-Ge
(1980) Surendra Singh; G.S. Verma
Optimized values of the valley-orbit splitting 4Δ and the donor-electron radius a0 for the different Sb-, As-, and P-doped Ge samples are obtained from the analysis of the resonance scattering of phonons which play a dominant role in the phonon resistivity of these materials in the liquid-helium range. Both elastic and inelastic scatterings from the singlet and triplet states as well as phonon-assisted absorption processes are considered in the calculations for the entire resonance region. Excellent agreement between theory and experiment is obtained for the optimized values of a0 and 4Δ. © 1980 The American Physical Society.