Browsing by Author "U.P. Singh"

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A case study of whistlers recorded at Varanasi (L = 1.07)
(Springer Berlin, 1998) R.P. Singh; U.P. Singh; Ashok K. Singh; D.P. Singh
Large number of high dispersion whistlers recorded at low latitude station Varanasi (L = 1.07) are analysed and it is find out that they have propagated along L ≃ 2.12-2.76. This is explained by considering the propagation of whistlers through the earth-ionosphere wave guide after exiting from the duct towards the equator. Using diffusive equilibrium model (DE-1), we have estimated equatorial electron density, total electron content in a flux tube and large scale convective electric fields which are in good agreement with the results reported by other workers from the analysis of mid latitude whistlers. The significance of this paper is to probe mid latitude plasmasphere using whistlers recorded at low latitudes. Further, an attempt has been made to study the propagation mechanism of low latitude whistlers.
A comparative study of energy and pitch angle diffusion during cyclotron resonance
(1996) U.P. Singh; D.P. Singh
Adopting linear and non-linear theories of wave-particle interaction, the relative importance of pitch angle diffusion over particle energy diffusion is examined for different ELF/VLF waves at different equatorial and off-equatorial locations for L values lying between 2 and 8. The result shows that the pitch angle diffusion is important in the plasmasphere where σ≤0.5, and the energy diffusion is important outside the plasmasphere where σ=0.6-0.8 (here σ=f/fH, f being the wave frequency and fH, the electron gyrofrequency). As such, the result indicates the dominance of wavegrowth over particle precipitation outside the plasmasphere and is useful for interpretation of high latitude and polar emissions.
A Naturally Occurring Resistant Forma Specialis of Phytophthora drechsleri to Metalaxyl
(1987) V.B. Chauhan; U.P. Singh
Metalaxyl was assayed in vitro against six species or formae speciales of Phytophthora. The ED50 values of metalaxyl for P. drechsleri, P. drechsleri, P. megasperma f. sp. medicaginis, P. megasperma f. sp. glycinae, P. boehmeriae, P. citricola and P. drechsleri f. sp. cajani ranged from 0.09–19.00 μg ml−1. The values for P. citricola and P. drechsleri f. sp. cajani were 6.45 and approximately 19.0 μg ml−,1. The ED90 values of all the species or forma speciales ranged from 0.9 to 199.0 μg ml−1. The ED90 for P. citricola and P. drechsleri f. sp. cajani was 48 and 199 μg ml−1, respectively.
A new species of cladochytrium from India
(Kluwer Academic Publishers, 1971) U.P. Singh; M.S. Pavgi
Morphology and development of a species of Cladochytrium N owakowski isolated from the soil are described in detail. The fungus is accommodated as a new species, Cladochytrium indicum sp. nov., in view of its morphological character distinctive from other species described so far. Formal descriptions are provided. © 1971 Dr. W. Junk Publishers.
A simple technique for studying the development of Erysiphe pisi in the epidermis of Pisum sativum
(Allen Press Inc., 1995) B. Prithiviraj; U.P. Singh
[No abstract available]
Acceptor states in Pd/n-GaAs devices and effect of hydrogenation
(1991) P.C. Srivastava; S. Chandra; U.P. Singh
Pd/n-GaAs devices have been fabricated and electrically characterized, before and after hydrogenation. The technique of hydrogenation is novel in the sense that the hydrogen absorbed in Pd provides a source of hydrogen at room temperature for its injection into GaAs by diffusion. The effective donor density decreases on hydrogenation. The forward bias C-V characteristics show the presence of two acceptor states at approximately 0.52 and approximately 0.72 eV for the unhydrogenated devices and at approximately 0.83 and approximately 0.92 eV for the hydrogenated devices. The likely origin of these states is discussed.
Additional evidence of stable EMF-induced changes in water revealed by fungal spore germination
(1994) S. Rai; U.P. Singh; G.D. Mishra; S.P. Singh; Samarketu
[No abstract available]
Additional evidence of stable EMF-induced changes in water revealed by fungal spore germination
(Informa Healthcare, 1994) Subas Rai; U.P. Singh; G.D. Mishra; S.P. Singh; Samarketu
Spore germination of some fungi was studied in EMF-tieated water samples. Water samples were exposed to 9.575 GHz microwave modulated with square waves of different pulse repetition frequencies. The study indicates varying inhibitory effects of different modulation frequencies on spore germination of Alternaria alternata, A. tenuissima, Fusarium udum, Helminthosorium oryzae, H. turcicumand Ustilago cynodontis. The pulse repetition frequency-dependent variation in spore germination caused by irradiated water illustrates that water may have the capability to store EMF frequency effects. EMF-treated water might have caused the effect by either changing the activities of and/or deactivating the spore enzymes. © 1994 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.
Al/n-Si diodes with low energy (∼100 eV) hydrogen ion implantation prior to metallization
(1994) P.C. Srivastava; C. Colluza; S. Chandra; U.P. Singh
[No abstract available]
An integrated approach to weed management practices in direct-seeded rice under zero-tilled rice–wheat cropping system
(Taylor and Francis Ltd., 2017) Dibakar Ghosh; U.P. Singh; K. Brahmachari; N.K. Singh; Anupam Das
An increasing water crisis as well as shortage of farm labor farmers in many Asian regions is forcing a shift from puddled transplanted rice to direct-seeded rice. The weeds, however, are a major constraint to the production of direct-seeded rice. In this perspective, a field study was carried out to evaluate various pre- and post-emergence herbicides and different possible integrated weed management practices in zero-till direct-seeded rice. Weed infestation decreased the rice yield by near about 75%. Co-culture rice with Sesbania followed by (fb) pendimethalin fb 2,4-D effectively reduced the total weed population (65.1%) and biomass (86.7%) at 30 days after sowing (DAS). The lowest total weed dry biomass at 60 DAS was recorded from bispyribac-sodium+azimsulfuron-treated plot and such tank mix application of herbicide performed better against diverse weed flora as compared to a single herbicide. Higher yield and more profit from zero-till direct-seeded rice were obtained with the application of bispyribac-sodium+azimsulfuron herbicides as a tank mixture or an integrated approach through cowpea green-manuring fb 2,4-D+glyphosate fb bispyribac-sodium by effective management of versatile weed flora. © 2016 Informa UK Limited, trading as Taylor & Francis Group.
Anastomoses and nuclear condition in Cephalosporium coccorum petch
(Kluwer Academic Publishers, 1972) U.P. Singh
Nuclear condition and formation of anastomoses in C. coccorumPetch have been reported. Preliminary study on the nuclear condition shows that the vegetative mycelium and conidia are uninucleate. Anastomoses in mycelium and conidia are discernible. Hyphal fusion through anastomosing bridges and nuclear migration through them show the possibility of heterokaryosis in the organism. Nutrient free medium is suitable for the development of anastomoses both in mycelium as well as in conidia. © 1972 Dr. W. Junk.
Antibiotic potential of plant growth promoting rhizobacteria (PGPR) against Sclerotium rolfsii
(2012) Amitabh Singh; Sudarshan Maurya; Rashmi Singh; U.P. Singh
High performance liquid chromatographic (HPLC) analysis of culture filtrates of plant growth promoting rhizobacteria (PGPR) and medium of inhibitory zone of interaction of Sclerotium rolfsii with PGPR, viz. Pseudomonas aeruginosa, Pseudomonas fluorescens 4, Pseudomonas fluorescens 4 (new) and Pseudomonas sp. varied from sample to sample. In all the culture filtrates of PGPRs, P. aeruginosa had nine phenolic acids in which ferulic acid (14.52 μg/ml) was maximum followed by other phenolic acids. However, the culture filtrates of P. fluorescens 4 had six phenolic acids with maximum ferulic acid (20.54 μg/ml) followed by indole acetic acid (IAA), caffeic, salicylic, o-coumeric acid and cinnamic acids. However, P. fluorescens 4 culture filtrate had seven phenolic acids in which salicylic acid was maximum (18.03 μg) followed by IAA, caffeic, vanillic, ferulic, o-coumeric and cinnamic acids. Pseudomonas sp. also showed eight phenolic acids where caffeic acid (2.75 μg) was maximum followed by trace amounts of ferulic, salicylic, IAA, vanillic, cinnamic, o-coumeric and tannic acids. The analysis of antibiosis zone of PGPRs showed fairly rich phenolic acids. A total of nine phenolic acids were detected in which caffeic acid was maximum (29.14 μg/g) followed by gallic (17.64 μg/g) and vanillic (3.52 μg/g) acids but others were in traces. In P. aeruginosa, antibiosis zone had seven phenolic acids where IAA was maximum (3.48 μg/g) followed by o-coumeric acid (2.08 μg/g), others were in traces. The medium of antibiosis zone of P. fluorescens 4 and P. fluorescens 4 new had eight phenolic acids in which IAA was maximum with other phenolic acids in traces. © 2012 Copyright Taylor and Francis Group, LLC.
Antifungal activity and induced resistance in pea by aqueous extract of vermicompost and for control of powdery mildew of pea and balsam
(2003) U.P. Singh; S. Maurya; D.P. Singh
Vermicompost (VC) is a nutritionally rich natural organic fertilizer, which releases nutrients relatively slowly in the soil. It improves quality of the plants along with physical and biological properties of soil, i. e., soil aeration, water-holding capacity and ecological balance of microbial soil biota. Aqueous extracts of vermicompost (AVC) inhibited spore germination of several fungi. They also affected the development of powdery mildews on balsam (Impatiens balsamina) and pea (Pisum sativum) caused by Erysiphe cichoracearum and Erysiphe pisi, respectively, in the field at very low concentrations (0.1-0.5 %). Soil amendment with VC (1-5%) induced synthesis of phenolic acids in pea. Maximum phenolic acids were detected in pea plants treated with 4% VC followed by 3% as compared to control. The induction of phenolic acids in plants was correlated with the degree of resistance in treated as compared to non-treated (control) pea plants. The growth of plants grown in VC-amended soil was much better than the growth of plants raised in non-amended soil.
Antifungal activity and kinetics of inhibition by essential oil isolated from leaves of Aegle marmelos
(1997) B.K. Rana; U.P. Singh; V. Taneja
The antifungal activity of essential oil isolated from the leaves of bael (Aegle marmelos (L.) Correa ex Roxb., Rutaceae) has been evaluated using spore germination assay. The oil exhibited variable efficacy against different fungal isolates and 100% inhibition of spore germination of all the fungi tested was observed at 500 ppm. However, the most resistant fungus, Fusarium udum was inhibited 80% at 400 ppm. Kinetic studies showed concentration as well as time dependent complex inhibition of spore germination by the essential oil.
Antifungal activity of an aqueous extract of leaves of garlic creeper (Adenocilymma alliaceum Miers.)
(1999) Bhupendra K. Rana; V. Taneja; U.P. Singh
The antifungal activity of an aqueous extract of the leaves of garlic creeper (Adenocalyxmna alliaceum Miers.) was tested against several fungi. The extract showed a broad fungitoxic spectrum as tested by inhibition of spore germination. Exposure of the spores of Alterniaria brassicae (Berk.) Sacc. to the extract for 5 min inhibited the spore germination by 72%, and after exposure for 10 min, a 100% inhibition was found. The inhibitory principle of the extract had a good shelf life at 10°C, and was thermostable when kept for 1 h at 60°C and on boiling at 100°C for 3 min. However, the inhibitory activity of the extract decreased to 70% on boiling for 5 min and was completely lost after boiling for 10 min.
Antifungal activity of anacardic acid, a naturally occurring derivative of salicylic acid
(Canadian Science Publishing, 1997) B. Prithiviraj; M. Manickam; U.P. Singh; A.B. Ray
The antifungal activity of anacardic acid and two of its derivatives was tested against some plant pathogenic fungi and the inhibitory effect was compared with that of salicylic acid. Anacardic acid was found to be most effective and it inhibited Colletotrichum capsici spore germination at 125-150μg mL-1. The results suggest that salicylic acid with appropriate structural modifications may prove to be a superior antifungal agent and can be utilized in controlling certain plant diseases under field conditions.
Antifungal activity of berberine iodide, a constituent of Fumaria indica
(Czech Academy of Sciences, 1999) B.K. Sarma; V.B. Pandey; G.D. Mishra; U.P. Singh
Berberine iodide, an isoquinoline alkaloid was isolated from Fumaria indica and its efficacy was tested against spore germination of some plant parasitic as well as saprophytic fungi. The alkaloid significantly curbed spore germination of Curvularia lunata, Erysiphe cichoracearum, E. pisi, Fusarium udum and Penicillium species. Complete inhibition (100 %) of spore germination was observed in E. cichoracearum and Penicillium species at 1.5 g/L. Albugo candida and Alternaria species were not affected by the chemical.
Antifungal activity of bergenin, a constituent of Flueggea microcarpa
(Blackwell Publishing Ltd, 1997) B. Prithiviraj; U.P. Singh; M. Manickam; J.S. Srivastava; A.B. Ray
The antifungal activity of bergenin against some plant pathogenic fungi, namely, Alternaria alternata, A. brassicae, A. carthami. Fusarium udum, F. oxysporum f. sp. ciceri, Curvularia lunata and Erysiphe pisi, was studied. Bergenin as its monosodium salt was effective against all the fungi and the effective dose for complete inhibition of spore germination varied from 15 μg mL-1 for F. udum to 125 μg mL-1 for E. pisi. Experiments on the effect of bergenin on powdery mildew development under glasshouse conditions revealed that it can control powdery mildew of pea at 2000 μg mL-1 by postinoculation treatment, the results being comparable with those of carbendazim (1000μg mL-1) and wettable sulfur (2000 μg mL-1). It affected hyphal elongation and the number of primary and secondary branches.
Antifungal activity of ethanolic extract of Archu (Rheum emodi) on powdery mildew (Erysiphe cichoracearum) and its role in the induction of resistance in balsam (Impatiens balsamania)
(2010) S. Maurya; Rashmi Singh; U.P. Singh
Rheum emodi, vernacularly known as Archu, is one of the important high altitude medicinal plants widely distributed in Himalayan regions. Though widely used in Ayurveda for curing various human diseases, its use in plant diseases is limited. Ethanolic extract of Rheum rhizome was assayed against spore germination of Alternaria solani, Heliminthosporium penniseti and Curvularia palliscens. The inhibition of spore germination was concentration dependent. Maximum inhibition was obtained at 4000 and 5000 ppm followed by 3000, 2000 and 1000 ppm. However, the extract was highly effective in the pre-inoculation treatment against powdery mildew (Erysiphe cichoracearum) of balsam (Impatiens balsamania) under field conditions. High performance liquid chromatographic (HPLC) analysis of balsam leaves showed increased synthesis of phenolic acids, which has been correlated with induced resistance in inhibiting the disease intensity of balsam powdery mildew. © 2010 Taylor & Francis.
Antifungal activity of neem (Azardirachta indica) toddy
(2010) U.P. Singh; S. Maurya; Amitabh Singh; Mandavi Singh
Neem (Azardirachta indica) is regarded as 'village pharmacy' in India due to its enormous use in the Indian villages as a folk medicine. Its different parts have been explored scientifically, except 'Neem toddy', which is a white secretion that exudes from the angle formed between the two major branches of old neem trees. The exact age of the tree upon the secretion of this white fluid is not known, nor why such a secretion occurs. It is normal, though rare, for such secretions to occur in old trees. The taste of neem toddy is bitter. The white milky liquid secretion, the 'neem toddy', was collected from the tree and assayed for the presence of phenolic acids by high performance liquid chromatography (HPLC). The phenolic acids detected were caffeic, vanillic, o-coumaric, cinnamic and salicylic acids. It was further fractionated by ethyl acetate and this fraction was tested against some fungi for antifungal activity. It was observed to be highly antifungal in vitro. Field experiments also showed its high efficacy against balsam (Impatiens balsamina) powdery mildew (Erysiphe cichoracearum). © 2010 Taylor & Francis.