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Articles by Ravindra Kumar
Total Records ( 6 ) for Ravindra Kumar
  Ravindra Kumar , Seweta Srivastava , Manisha Srivastava and Asha Sinha
  In present study, the influences of different organic soil amendments on soil fungi was studied. Soil organisms carry a wide range of processor that are important for soil health and partially in both natural and managed agricultural scales. The total number of organisms, the diversity of species and activity of soil biota will fluctuate as soil environment changes. Three types of soil amendments and fertilizers viz., urea, FYM and vermicompost were used to amend the cultivated agricultural soil. The fungi were isolated from soil by using dilution plate technique and soil plate method. The dynamics of soil fungi were observed qualitatively as well as quantitatively. The maximum number of fungi was recorded when soil amended with FYM (40.6x104 g-1), urea (38.8x104 g-1) of dry soil at different concentration 2.0, 1.5 and 2.0%, respectively. In control where soil was not amended with any organic amendment, the number of fungi was 13.0x104 to 16.8x104 g-1, 14.4x104 to 16.8x104 g-1, 13.8x104 to 16.8x104 g-1 in urea, FYM and Vermicompost, respectively. A total 25 fungi were observed during the experimental period. Eighteen were observed when soil amended with urea, twenty-two observed when soil amended with FYM and 20 when soil amended with vermicompost. In control soil only fifteen fungi were recorded. The result showed that the number of fungi was increased in amended soil. Qualitatively, the fungi Rhizopus stolonifer, Aspergillus niger, Aspergillus flavus, Trichoderma harzianum, Penicillium citrinum, Alternaria alternata and Curvularia lunata, White Sterile Mycelium and Black Sterile Mycelium were observed.
  Ravindra Kumar , Asha Sinha , Seweta Srivastava and Manisha Srivastava
  The aim of the present study was to determine the decomposition rate of Sesbania aculeata L. by CO2 evolution and to estimate Soluble Crude Protein (SCP) production by dominant decomposing mycoflora of Sesbania aculeata L. Eight dominant decomposing mycobiota were selected for the study. In the substrate induced respiration the significant difference was observed in both sterilized and unsterilized substrate with the test fungi. The maximum CO2 evolution was observed with Aspergillus niger in sterilized (16.04 μg day-1) and unsterilized green manure (18.92 μg day-1). In other experiment conducted for the estimation of soluble crude protein production Penicillium citrinum has produced maximum SCP (26.54%) at 25°C followed by Trichoderma harzianum, Aspergillus niger and Curvularia lunata whereas minimum soluble crude protein production was observed in Penicillium rubrum (8.46%) at 35°C. The maximum per cent biomass reduction observed by Aspergillus niger (28.60%) at 25°C and minimum was found in Penicillium rubrum (3.80%) at 35°C. Among seven different nitrogen sources tested against Penicillium citrinum, the highest producer of SCP, potassium nitrate was found to be the best for maximum SCP production (26.54%) whereas the least suitable nitrogen source for SCP production by Penicillium citrinum was recorded to be sodium nitrate (14.85%).
  Seweta Srivastava , Ravindra Kumar and Asha Sinha
  Various parts of the Jatropha curcas plant are of medicinal value, its wood and fruit can be used for numerous purposes including fuel. In the present study the effectiveness of Jatropha curcas oil on inactivation of some mycoflora were determined. As a measure of testing the antimicrobial property of Jatropha curcas oil were subjected against six selected fungi viz. Alternaria alternata, Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Fusarium chlamydosporum and Penicillium glabrum. Poisoned food technique was used to evaluate the antifungal effect of J. curcas oil. Two different concentrations of Jatropha oil i.e., 100 μL and 500 μL were mixed with potato dextrose agar (PDA) medium in Petri plates. Maximum radial growth was shown by control of Aspergillus flavus, Aspergillus fumigatus and Aspergillus niger i.e., 90 mm (full growth on petri plate) followed by the control of Alternaria alternata i.e., 77.3 mm and minimum growth was shown by Penicillium glabrum i.e., 21 mm followed by Aspergillus niger i.e., 33 mm at 500 μL concentration of Jatropha oil. Maximum percent inhibition was shown by Penicillium glabrum i.e., 82.96% followed by Aspergillus niger i.e., 63.33% at 500 μL concentration of Jatropha oil and minimum percent inhibition was shown by Fusarium chlamydosporum i.e., 31.59% at 100 μL concentration of Jatropha oil. From this experiment it was concluded that Jatropha oil has promising antifungal effect on Penicillium glabrum and Aspergillus niger.
  Ravindra Kumar , Anuja Gupta , V.K. Maheshwari and S.S. Atwal
  Rice (Oryza sativa L.) is one of the major food crops of the world. Due to lack of awareness, the farmers do not distinguish the seed from grain and hence the quality of farmers saved seed remains below standard. This seed carries microflora which play an important role in reducing the seed viability. Among seed microflora, fungal load on the seed is very important. In this study, seed samples of different varieties of paddy were collected from farmers in different villages of Haryana from 2002 to 2012. The seed was subjected to seed health test by blotter technique and observed under stereo-binocular microscope to assess its fungal load. The per cent germination and vigour index were also evaluated by paper towel method. A total of 30 fungi belonging to different groups were recorded from the samples of farmers’ saved seed. Alternaria padwickii (28.52%), Curvularia lunata (22.67%), Alternaria alternata (10.51%), Rhizopus stolonifer (8.96%), Aspergillus flavus (8.26%) and Fusarium moniliforme (7.15%) were recorded as major fungi associated with the seed. However, in breeder seed of different paddy varieties grown at this station, only 22 fungal species belonging to different groups were recorded. Out of which Alternaria padwickii (10.62%), Curvularia lunata (7.35%), Alternaria alternata (6.54%), Aspergillus flavus (6.07%) and Rhizopus stolonifer (5.21%) were recorded as the major fungi associated with this seed. Average per cent germination and vigour of farmers’ saved seed of different paddy varieties was significantly lower than the breeder seed of different varieties of paddy grown at this station.
  Anuja Gupta , Ravindra Kumar and V.K. Maheshwari
  Bakanae disease of rice caused by Fusarium fujikuroi is widespread in all rice growing countries of the world and is of great concern especially in Basmati paddy. Different management practices viz. seed treatments, seedling dip treatments and soil amendments were integrated for the management of bakanae disease in Paddy variety Pusa Basmati 1121. Seed treatment with carbendazim (Bavistin) and Trichoderma viride gave 22.7 and 11.4% control of the disease. However, the disease incidence did not vary much amongst different seed treatments under FYM+T. viride treated soil conditions. Seed treatment with bavistin and T. viride gave 10.1 and 10.2% disease, respectively as against 10.3% in crop grown from untreated seed under FYM+T. viride soil condition. Seedling dip in 0.2% bavistin or 0.4% T. viride solution before transplanting significantly reduced the disease incidence. Seedling dip treatments with bavistin and T. viride solutions resulted in 55.5 and 34.5% control of the disease, respectively, irrespective of soil amendments. The disease incidence was 10.3 and 11.8% in FYM+T. viride treated soil and T. viride treated soil, respectively as against 13.6% in untreated soil. The highest disease incidence (27.3%) was recorded in non-amended soils (control) transplanted from nursery of untreated seeds and the seedlings dipped in plain water at the time of transplanting. The disease control in FYM+T. viride treated soil and T. viride treated soil was statistically at par and significantly superior to untreated soil. The grain yield in plots transplanted from all the seed treatment and seedling dip treatment were statistically superior to plots transplanted from nursery raised from untreated seed and seedling dipped in plain water.
  Scott W. Nelson , Ravindra Kumar and Stephen J. Benkovic
  In T4 phage, coordinated leading and lagging strand DNA synthesis is carried out by an eight-protein complex termed the replisome. The control of lagging strand DNA synthesis depends on a highly dynamic replisome with several proteins entering and leaving during DNA replication. Here we examine the role of single-stranded binding protein (gp32) in the repetitive cycles of lagging strand synthesis. Removal of the protein-interacting domain of gp32 results in a reduction in the number of primers synthesized and in the efficiency of primer transfer to the polymerase. We find that the primase protein is moderately processive, and this processivity depends on the presence of full-length gp32 at the replication fork. Surprisingly, we find that an increase in the efficiency of primer transfer to the clamp protein correlates with a decrease in the dissociation rate of the primase from the replisome. These findings result in a revised model of lagging strand DNA synthesis where the primase remains as part of the replisome after each successful cycle of Okazaki fragment synthesis. A delay in primer transfer results in an increased probability of the primase dissociating from the replication fork. The interplay between gp32, primase, clamp, and clamp loader dictates the rate and efficiency of primer synthesis, polymerase recycling, and primer transfer to the polymerase.
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