• G B Pradhan

      Articles written in Proceedings – Animal Sciences

    • Rhizosphere effect ofAndropogon pumilus Roxb. on soil nematodes, soil organic matter and nitrogen

      G B Pradhan M C Dash

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      The rhizosphere effect ofAndropogon pumilus Roxb. on soil nematodes, percent organic matter and percent total nitrogen has been studied and compared with nonrhizosphere soils. The proportion of plant parasites and microbivores were considerably higher than the proportion of miscellaneous feeders and predators in the rhizosphere than in the root free soils. Nematode population in the rhizosphere reached a peak during the flowering stage in November. Nematode density, percent organic matter and percent total nitrogen were significantly more in the rhizosphere soil than the root free soil. In the rhizosphere soil nematode abundance showed a significant positive correlation with percent organic matter and percent total nitrogen indicating that the root exudates promote increase in the population of micro-organisms and nematodes.

    • Distribution and population dynamics of soil nematodes in a tropical forest ecosystem from Sambalpur, India

      G B Pradhan M C Dash

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      An ecological study on soil nematodes was made in a tropical deciduous forest ecosystem. Seventeen species of nematodes were identified of whichRotylenchus sp. was the dominant plant parasitic form andAcrobeloides sp. was the dominant microbivore species. The mean annual importance value for the miscellaneous feeders, plant parasites, microbivores and predators were 57·5, 22·5, 12·6 and 7·4 respectively. The Shannon index of general divérsity was maximum during February (1·73) and minimum during June (1·41). Nematodes were distributed in clusters resulting in so called pocket effect. Of the total nematodes 88·4% occurred in the top 10 cm soil during the peak period of density and the microbivores were more frequent in the top 5 cm soil due to the litter layer. Total nematode density ranged from 15·1 × 104/m2 (May) to 66·1 × 104/m2 (November). Monthly mean nematode biomass was 18·86 ± 8·36 mg dry wt/m2. Temperature, soil organic carbon and soil total nitrogen apparently played an important role in regulating the nematode population.

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