Akash Tomar

Effect of nutrient status, temperature and PH on mycelial growth, sclerotial production and germination of Rhizoctonia Solani Isolated from paddy fields

Rhizoctonia solani Kuhn, is one of the most important pathogen of rice causing sheath blight disease, which accounts for heavy yield losses in all the major rice growing areas of the world including India. In the present investigation the effect of different culture media, carbon and nitrogen sources, temperature and pH on mycelial growth, sclerotia production and germination of Rhizoctonia solani (anastomosis groups AG1-IA from rice and AG3 from potato) were studied. Among the five culture media including potato dextrose agar (PDA), malt yeast extract agar (MYA), water agar (WA), oat meal agar (OMA) and soil extract agar (SEA), PDA medium supported maximum mycelial growth and sclerotium yield. The maximum mycelial growth and sclerotia formation was observed in D-glucose as carbon source while the maximum mycelial growth and sclerotia formation was recorded in potassium nitrate as nitrogen source. Different range of temperatures i.e. 10, 15, 20, 25, 30 and 35°C were tested and the maximum hyphal growth was measured at 25°C temperature. Mycelial growth of all isolates occurred between pH 4.0 and 9.0, with an optimum of pH 5.6. Sclerotium germination for all the AG1-IA isolates was optimum between 20 and 30°C on all the media tested, with a pH optimum between pH 5.0 and 6.0.

Bio-efficacy of isolated local microbial strains against Fusarium oxysporum of Tomato

A total of nineteen soil samples were collected from different regions of Moradabad, JP Nagar, Bhind and Gwalior and adjoining areas. Trichoderma strains were isolated, and identified on the basis of morphological and microscopic studies. These strains were further screened for their bio-efficacy against Fusarium, a pest of tomato. The inhibitions efficiency of isolated strains varied between 62.3–73.7%.

Physio-Biochemical Alterations Under Moisture Deficit Stress At Different Growth Stages Of Rice (Oryza Sativa. L)

Moisture deficit stress or drought is one of the persistent challenges for the survival of the rice plants to maintain its proper growth and productivity. Drought can occur at any stage of growth and development of rice. In response to the drought stress, various physiological and biochemical alterations have been employed by plant to cope up its adverse effects. Two contrasting rice varieties, Nagina22 (drought resistant) and IR64 (drought sensitive) were studied at 3 stages i.e. seedling, vegetative and reproductive stage under well watered (control) and moisture deficit stress conditions. This present study focuses at identifying changes in physiological and biochemical parameters between Nagina22 and IR64. The mean values of Relative Water Content (RWC), Membrane Stability Index (MSI), Chlorophyll a, Chlorophyll b, and Total chlorophyll decreases significantly during drought stress at different stages. But Proline showed remarkable increase during drought stress at reproductive stage in Nagina22 as compared to IR64. So we conclude that nagina22 is highly tolerant to drought stress than IR64 at reproductive stage.

Morphological, Cultural and Physiological Variations among Isolates of Colletotrichum Falcatum went That Cause Red Rot Disease of Sugarcane

Sugarcane is an important economical cash crop grown over an area of about 5.07 Mha in India. Red rot disease caused by the fungus Colletotrichum falcatum Went., is the most important and the dreaded disease affecting adversely the production of millable canes in India. Five isolates of C. falcatum were procured from ISSR, Lucknow; the culture was maintained on slants and Petri plates at 29°C. Variation in the cultural, morphological and physiological characteristics among the 5 isolates was investigated. These isolates were morphologically differentiated into two distinct groups: light colour and dark colour types based on the colony colour character. Three isolates (RR-08, RR-02 and RR-07) in the dark type produced gray colour colonies whereas isolates Cf-09 and Cf-08 in the light type had white colour colonies. The growth rate among all isolates varied from 10.6 to 11.9 mm.d-1 and was not significantly different. The five isolates produced setae and conidia that were hyaline, one-celled, falcate or sickle-shaped. The conidia of all isolates ranged between 31.2 and 36.5 μm in length and from 10.1 and 11.2 μm μm in width. All isolates were varied in their physiological characteristics. The optimum physical parameters for mycelial growth of the five strains was found to be 30°C for temperature, 5.5 (for four isolates viz., Cf-09, Cf-08, RR-08, RR-07) and 6.0 (for isolate RR-02) for pH. Host extract media maintained the highest mycelial growth in all the five isolates followed by PD broth. Dextrose and potassium nitrate were found to the best sources of carbon and nitrogen, respectively for maximum mycelial growth of Cf-09, Cf-08, RR-08 and RR-02 isolates while glucose and sodium nitrate were the best source of carbon and nitrogen, respectively for RR-07 isolate of C. falcatum. We have found that Colletotrichum falcatum isolates were culturally, morphologically and physiologically dissimilar.

Isolation and Characterization of E. coli from Food and Environmental samples and its Antibiotic Sensitivity Profile

Escherichia coli is not always confined to the intestine and their ability to survive for brief periods outside the body make them an ideal indicator organism to test environmental samples for fecal contamination. Meat plays an important role in human nutrition. It also acts as favorable medium for growth as well as transmission of various microbes. The type and level of bacterial contamination of meat have important consequences in relation to public health, shelf-life and the type of spoilage. Human beings consuming contaminated meat may often become infected with food-borne pathogens. The emergence of bacteria resistant to most of the commonly used antibiotics/drugs is of considerable medical significance. Antibiogram of all the isolates was done with 8 different antibiotics. Different isolates show different responses to antibiotics. E. coli isolates were highly sensitive to antibiotic Kanamycin (80%), followed by Chloramphenicol (60%). The least sensitivity are showing against antibiotic Ciprofloxacin (40%), Nitrofurantoin (40%) and Streptomycin (20%). None of the E. coli isolates showed sensitivity to Carbenicillin followed by tetracycline (only 1 isolate shows partial/intermediate sensitivity).