Browsing by Author "A.K. Sharma"

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A review on crop losses, epidemiology and disease management of rice brown spot to identify research priorities and knowledge gaps
(2013) M.K. Barnwal; A. Kotasthane; N. Magculia; P.K. Mukherjee; S. Savary; A.K. Sharma; H.B. Singh; U.S. Singh; A.H. Sparks; M. Variar; N. Zaidi
Rice brown spot (BS) is a chronic disease that affects millions of hectares of rice every growing season, grown by some of the most resource-poor farmers. Despite its widespread occurrence and impact, much still needs to be understood about BS. Reported yield losses in relative terms vary widely from 4 to 52 %. However, accurate, systematic estimates are lacking. BS is conventionally perceived as a secondary problem that reflects rice crops that experience physiological stresses, e. g. drought and poor soil fertility, rather than a true infectious disease. Much remains to be understood about the mechanisms leading to epidemics and crop losses. Quantitative and qualitative knowledge gaps exist in our understanding of the epidemiological processes, sources of resistance and biocontrol methods. In this review we identify several of these gaps, which if filled, could lead to a strong impact on the management of brown spot. We also use the architecture of a simulation model to position and prioritize these knowledge gaps, assess the epidemiological consequences of disease management options on BS monocyclic processes and explore the impact changing production situations on this important disease. © 2013 The Author(s).
Calibration strategy of INSAT-3D meteorological satellite imager using the moon at IMD, New Delhi
(SPIE, 2016) Shailesh Parihar; A.K. Sharma; A.K. Mitra; M. Mohapatra; L.S. Rathore; R. Bhatla; R.S. Singh
Lunar measurements are part of the calibration strategy for the instruments in Earth Observing System and satellites. The purpose of using moon as an absolute radiometric standard for calibration it is used solely as a diffuse reflector whose surface remains unchanged. INSAT-3D is India's meteorological geostationary satellite an exclusive next-generation mission designed for enhanced meteorological observations having 6 channel imager and 18 channel sounder. INSAT-3D Spacecraft was dedicated to Nation at National Satellite Meteorological Center (NSMC) indigenously designed developed INSAT-3D Meteorological Data Processing System (IMDPS), commissioned at India Meteorological Department (IMD) New Delhi on January 15, 2014. The Moon is being observed from INSAT-3D regularly in the of full-disk operational image of earth with rectangular field of regard in IMDPS New Delhi. INSAT-3D measurements of lunar surface observed in Visible (0.55 - 0.75μm), Short Wave Infrared 1.55 - 1.70μm, Mid Wave Infrared (3.80 - 4.00μm), Water Vapor (WV) 6.50 - 7.10μm, Thermal Infrared (TIR) 1 & 2, 10.3 - 11.3μm & 11.5 - 12.5μm wavelength regions. The visible and infrared wavelengths region provide a new and intriguing methodology of distinguish in sensitivities of Earth observing radiometers. © 2016 SPIE.
Chemical management of seed-borne diseases: Achievements and future challenges
(Springer Singapore, 2020) Udai B. Singh; Rajan Chaurasia; Nazia Manzar; Abhijeet S. Kashyap; Deepti Malviya; Shailendra Singh; Pooja Kannojia; P.K. Sharma; Imran Mohd.; A.K. Sharma
Seed is a basic and most important input for agriculture and high-quality seed is also required in international seed trading. There are many seed-borne diseases and pathogens that have negative impact on seed health and its quality. Seed-borne inoculums are the main source of primary infection leading to disease development. The disease gets established in the field wherever the infected seed is used and causes severe yield losses. Paul Neergaard is considered as father of seed pathology who has contributed a lot in the development of seed pathology. Seed-borne pathogenic microorganisms mainly fungi, viruses and bacteria are greatly affecting seed quality and cause diseases that affect seedling production in the nurseries. Management strategies for the control of various seed-borne diseases are mainly based on chemical seed treatment. Studies have been carried out with a view to find out the best way to use chemicals in seed production. Such studies are very few, and hence, there is a need to conduct further research so that new chemicals could be incorporated into seed-borne disease management programmes. We need to have additional ways to control diseases that are seed-borne, and chemical pesticides are effective against a wide spectrum of diseases. This chapter provides a brief review of seed-borne pathogen problems that affect seeds and discusses established and potential control practices by using chemicals like fungicides, insecticides or defence activators and further gives the future perspectives where focus should be given with respect to seed pathology and management of seed-borne disease. © Springer Nature Singapore Pte Ltd. 2020.
Effect of organic, inorganic and plant growth promoting rhizobacteria (PGPR) on growth and yield of cabbage in mid hills of himachal pradesh and study of their economics
(Society for Plant Research, 2017) P. Yadav Ram; A.K. Sharma; Rajesh Kaushal; Maneesh Kumar Singh; Ashish Kumar Maurya
The present investigation was carried out with cabbage cv. Pusa Mukta in a randomized complete block design with three replications with the objective to evolve integrated plant nutrient supply system for higher productivity of cabbage on sustainable basis. The experiment comprised of 15 different combinations of three different sources of nutrients including organic, inorganic and PGPR alone and in combinations which were applied following the proper procedures as per treatment. Integrated use of fertilizers, manures and PGPR significantly influenced yield and plant growth attributes of cabbage crop. The conjoint use of 75 % recommended dose of NP + Vermi compost and Enriched compost @ 2.5 t/ha + PGPR (T14) resulted in significantly maximum gross head weight (1580 g), net head weight (1050 g), harvesting index (66.45 %) and head yield (530.34 q/ha). This treatment recorded 34.4 per cent increase in yield over recommended practice (T1) along with highest net returns (Rs.3, 89,992/-). From present investigation, it can be concluded that above integrated combination of chemical fertilizers, organic manures (VC and EC) and PGPR resulted in saving of 25 % chemical fertilizers (NP), better growth, higher yield which statistically matched with the recommended package of fertilization which utilized 100 % NPK along with 20 t FYM. © 2017, SPR, All Rights Reserved.
Mining of Indian wheat germplasm collection for adult plant resistance to leaf rust
(Public Library of Science, 2019) Sundeep Kumar; B.S. Phogat; V.K. Vikas; A.K. Sharma; M.S. Saharan; Amit Kumar Singh; Jyoti Kumari; Rakesh Singh; Sherry Rachel Jacob; G.P. Singh; M. Sivasamy; P. Jayaprakash; M. Meeta; J.P. Jaiswal; Deep Shikha; B.K. Honrao; I.K. Kalappanavar; P.C. Mishra; S.P. Singh; S.S. Vaish; V.A. Solanki
Leaf rust (Puccinia triticina Eriks.) is a fungal disease of wheat (Triticum spp.), which causes considerable yield loss. Adult plant resistance (APR) is one of the most sustainable approaches to control leaf rust. In this study, field-testing was carried out across ten different locations, followed by molecular screening, to detect the presence of APR genes, Lr34+, Lr46+, Lr67+ and Lr68 in Indian wheat germplasm. In field screening, 190 wheat accessions were selected from 6,319 accessions based on leaf tip necrosis (LTN), disease severity and the average coefficient of infection. Molecular screening revealed that 73% of the accessions possessed known APR genes either as single or as a combination of two or three genes. The occurrence of increased LTN intensity, decreased leaf rust severity and greater expression of APR genes were more in relatively cooler locations. In 52 lines, although the presence of the APR genes was not detected, it still displayed high levels of resistance. Furthermore, 49 accessions possessing either two or three APR genes were evaluated for stability across locations for grain yield. It emerged that eight accessions had wider adaptability. Resistance based on APR genes, in the background of high yielding cultivars, is expected to provide a high level of race non-specific resistance, which is durable. © 2019 Kumar et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Molecular and pathological screening of canine distemper virus in Asiatic lions, tigers, leopards, snow leopards, clouded leopards, leopard cats, jungle cats, civet cats, fishing cat, and jaguar of different states, India
(Elsevier B.V., 2022) Rahul Ganpatrao Kadam; M. Karikalan; Chandra Mohan Siddappa; K. Mahendran; Gaurav Srivastava; K.K. Rajak; Yogesh Bhardwaj; Rajat Varshney; Zahoor Ahemad War; Rahul Singh; Mayukh Ghosh; V. Beena; Abhijit M. Pawde; K.P. Singh; A.K. Sharma
The present investigation was conducted to rule out canine distemper (CD) diseases in Indian wild felids (Asiatic lions, tigers, leopards, snow leopards, clouded leopards, leopard cats, jungle cats, civet cats, fishing cat, and jaguar). The collected samples were screened for CD virus (CDV) by histopathology (HP), immunohistochemistry (IHC) and reverse transcriptase-polymerase chain reaction (RT-PCR) targeting H gene and N gene. The HP and IHC of suspected samples portrayed that 22 [11 leopards, 6 lions, 3 tigers, 1 snow leopard and 1 civet cat] out of 129 (17.05%) wild felids were positive for CD. The major pathological consequences were observed in spleen, lung, kidney and brain. The syncytia and intranuclear as well as intracytoplasmic eosinophilic inclusion bodies were seen in CDV infected cells. Although the histopathological lesions in spleen were more specific and consistent, however, the severe demyelinated leukoencephalitis (usually expected in CD infected dog) was not observed in the brain of any Indian wild felids. Conversely, the CDV antigen has been portrayed via IHC in pancreatic islets of Langerhans of tiger species for the first time in this study. Moreover, the concurrent CD and babesiosis has also been observed in a lioness without a usual coffee-coloured urine. The N gene and H gene of CDV isolates were amplified, sequenced and subsequently constructed the phylogenetic tree. The phylogenetic analysis of H gene revealed that the CDV isolates from Indian lion formed separate clade with CDV isolates from Indian dog and Indian palm civet cat. Furthermore, two CDV isolates from Indian tigers formed clade with Onderstepoort vaccine strain and CDV isolates from dogs of Uttar Pradesh, USA and UK. Evidently, CDV is circulating in Indian wild felids and causing diseases in them. © 2022 The Author(s)
Performance analysis of a modified solar array under shadow conditions
(1994) A.K. Sharma; R. Dwivedi; S.K. Srivastava; C.M. Pathak
This paper deals with the performance studies of a photovoltaic panel under shadow conditions. The conventional solar array design approach has been modified using a bypass diode across each cell, and the performance of the modified panel has been evaluated experimentally. The observed experimental results have been compared to those obtained theoretically, taking account of the effect of additional series resistance due to the shadowed area. Excellent agreement, both qualitatively and quantitatively, between experiment and theory has been obtained. © 1994.
Performance analysis of a solar array under shadow condition
(1991) A.K. Sharma; R. Dwivedi; S.K. Srivastava
The investigation deals with performance studies of a solar array consisting of two modules, each having 25 cells in series. The load characteristics of the array are studied experimentally and it is observed that, as the shadowed area increases, the overall performance of the array is significantly degraded. Theoretical analysis of such an array has also been carried out to explore the possible mechanisms responsible for array degradation. In the analysis, we consider an additional series resistance for the dark region, whereas earlier workers have overestimated the contribution of the dark region because they have always taken into account identical series resistances for the illuminated, as well as the dark, region. Simulation of the enhanced series resistance of the dark region in the present work has been done by the effective surface resistance of the emitter layer caused by a metallic grid, because of the biasing of the dark region by the illuminated area. Under such biasing, the dark region acts as a load on the illuminated region and causes a loss of current. This is simulated by an additional series resistance (Rsurf). The analysis, which is based on consideration of the enhanced series resistance of the dark region, produces a better match between experimental and theoretical results.
Site characterization for calibration of radiometric sensors using vicarious method
(SPIE, 2016) Shailesh Parihar; L.S. Rathore; M. Mohapatra; A.K. Sharma; A.K. Mitra; R. Bhatla; R.S. Singh; Yogdeep Desai; Shailendra S. Srivastava
Radiometric performances of earth observation satellite/sensors vary from ground pre-launch calibration campaign to post launch period extended to lifetime of the satellite due to launching vibrations. Therefore calibration is carried out worldwide through various methods throughout satellite lifetime. In India Indian Space Research Organization (ISRO) calibrates the sensor of Resourcesat-2 satellite by vicarious method. One of these vicarious calibration methods is the reflectance-based approach that is applied in this study for radiometric calibration of sensors on-board Resouresat-2 satellite. The results of ground-based measurement of atmospheric conditions and surface reflectance are made at Bap, Rajasthan Calibration/Validation (Cal/Val) site. Cal/Val observations at site were carried out with hyper-spectral Spectroradiometer covering spectral range of 350nm- 2500nm for radiometric characterization of the site. The Sunphotometer/Ozonometer for measuring the atmospheric parameters has also been used. The calibrated radiance is converted to absolute at-sensor spectral reflectance and Top-Of-Atmosphere (TOA) radiance. TOA radiance was computed using radiative transfer model 'Second simulation of the satellite signal in the solar spectrum' (6S), which can accurately simulate the problems introduced by the presence of the atmosphere along the path from Sun to target (surface) to Sensor. The methodology for band averaged reflectance retrieval and spectral reflectance fitting process are described. Then the spectral reflectance and atmospheric parameters are put into 6S code to predict TOA radiance which compare with Resourcesat-2 radiance. Spectral signature and its reflectance ratio indicate the uniformity of the site. Thus the study proves that the selected site is suitable for vicarious calibration of sensor of Resourcesat-2. Further the study demonstrates the procedure for similar exercise for site selection for Cal/Val analysis of other satellite over India region. COPYRIGHT © SPIE. Downloading of the abstract is permitted for personal use only.
Trichoderma harzianum-and methyl jasmonate-induced resistance to bipolaris sorokiniana through enhanced phenylpropanoid activities in bread wheat (Triticum aestivum L.)
(Frontiers Media S.A., 2019) Udai B. Singh; Deepti Malviya; Shailendra Singh; Manoj Kumar; Pramod K. Sahu; H.V. Singh; Sunil Kumar; Manish Roy; Mohd. Imran; Jai P. Rai; A.K. Sharma; A.K. Saxena
The aim of the present study was to evaluate the impact of Trichoderma harzianum UBSTH-501-and methyl jasmonate-induced systemic resistance and their integration on the spot blotch pathogen, Bipolaris sorokiniana through enhanced phenylpropanoid activities in bread wheat (Triticum aestivum L.). It was found that the application of MeJA (>100 mg L−1 ) inhibits the germination of B. sorokiniana spores under controlled laboratory conditions. To assess the effect of MeJA (150 mg L−1 ) in combination with the biocontrol agent T. harzianum UBSTH-501 in vivo, a green house experiment was conducted. For this, biocontrol agent T. harzianum UBSTH-501 was applied as seed treatment, whereas MeJA (150 mg L−1 ) was applied 5 days prior to pathogen inoculation. Results indicated that application of MeJA (150 mg L−1 ) did not affect the root colonization of wheat by T. harzianum UBSTH-501 in the rhizosphere. The combined application of T. harzianum UBSTH-501 and MeJA also enhanced indole acetic acid production in the rhizosphere (4.92 µg g−1 of soil) which in turn helps in plant growth and development. Further, the combined application found to enhance the activities of defense related enzymes viz. catalase (5.92 EU min−1 g−1 fresh wt.), ascorbate peroxidase [µmol ascorbate oxidized (mg prot)−1 min−1 ], phenylalanine ammonia lyase (102.25 µmol cinnamic acid h−1 mg−1 fresh wt.) and peroxidase (6.95 Unit mg−1 min−1 fresh wt.) significantly in the plants under treatment which was further confirmed by assessing the transcript level of PAL and peroxidase genes using semi-quantitative PCR approach. The results showed manifold increase in salicylic acid (SA) along with enhanced accumulation of total free phenolics, ferulic acid, caffeic acid, coumaric acid, and chlorogenic acid in the leaves of the plants treated with the biocontrol agent alone or in combination with MeJA. A significant decrease in the disease severity (17.46%) and area under disease progress curve (630.32) were also observed in the treatments with biocontrol agent and MeJA in combination as compared to B. sorokiniana alone treated plant (56.95% and 945.50, respectively). Up-regulation of phenylpropanoid cascades in response to exogenous application of MeJA and the biocontrol agent was observed. It was depicted from the results that PAL is the primary route for lignin production in wheat which reduces cell wall disruption and tissue disintegration and increases suberization and lignification of the plant cell as seen by Scanning Electron microphotographs. These results clearly indicated that exogenous application of MeJA with T. harzianum inducing JA-and/or SA-dependent defense signaling after pathogen challenge may increase the resistance to spot blotch by stimulating enzymatic activities and the accumulation of phenolic compounds in a cooperative manner. This study apparently provides the evidence of biochemical cross-talk and physiological responses in wheat following MeJA and biocontrol agent treatment during the bio-trophic infection. © 2019 Singh, Malviya, Singh, Kumar, Sahu, Singh, Kumar, Roy, Imran, Rai, Sharma and Saxena.