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B. Bhattacharjee , B. K. Dutta

Abstract

A study was carried out to investigate the ideal host plants for orchid diversity of Southern Assam. Five selected commonly available species of the valley were chosen in the study by Braun Blanquet cover abundance scale method. After analysis, Lagerstroemia reginae Roxb. has been observed to be the most suitable host plant of orchids followed by others, in three Reserve Forests where the study was carried out.

Keywords

Lagerstroemia reginae, Orchid, Southern Assam, Braun-Blanquet Cover Abundance
Scale

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R. K. Gupta , S. K. Saxena , B. K. Dutta

Abstract

no abstract

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Dipendra Singha ¹, Baby Singha ², B. K. Dutta ¹

Affiliations
1 Department of Ecology & Environmental Sciences, Assam University, Silchar 788 011, Assam, IN
2 Department of Zoology, G. C. College, Silchar 788 004, Assam, IN

Abstract

Tea is an economically important plantation crop of Assam, India. Termites are one of the predominant pests causing damage to tea, thereby affecting the productivity and quality. Bacillus thuringiensis strains are widely used as microbial control agents for different insect pests. In the present study B. thuringiensis and B. thuringiensis subsp. israelensis were evaluated in vitro for their pathogenicity against two species of tea termites, viz., Microtermes obesi Holmgren and Microcerotermes beesoni Snyder. Bacillus thuringiensis strains caused mortality of above 80% in both the termite species. B. thuringiensis subsp. israelensis was found to be more virulent compared to B. thuringiensis against the termites.

Keywords

Microcerotermes beesoni, Microtermes obesi, Median Lethal Time.

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Romila Thoudam ¹, B. K. Dutta ¹

Affiliations
1 Microbial and Agricultural Ecology and Biodiversity Conservation Laboratory, Department of Ecology and Environmental Sciences, Assam University, Silchar 788 011, Assam, IN

Abstract

The potential of some aeromycoflora and the tea phyllosphere micro organisms to control black rot disease of tea (causal organism - Corticium theae Bernard) was evaluated. Fungal microorganisms isolated from the tea plantation environment and phyllosphere of 11 clones of tea were evaluated. The fungal genera most frequently trapped from the environment of tea plantation were Aspergillus flavus, Aspergillus niger, Curvularia sp., Penicillium sp. and Trichoderma atroviride. The most frequently recovered mycoflora from the tea phyllosphere are Aspergillus flavus, Aspergillus niger, Penicillium sp., Trichoderma atroviride and Trichoderma citrinoviride. Experiment was carried out to assess the possible use of these micro organisms as biocontrol agents against the black rot disease of tea causing organism i.e. Corticium theae under in vitro and field conditions. The aqueous solution of the antagonists which showed maximum inhibition of the pathogen in vitro was applied under field conditions as foliar spray. The percentage symptom and senility index was found to be lowest in the plots sprayed with A. niger followed by T. atroviride and T. citrinoviride, respectively.

Keywords

Aeromycoflora, Antagonists, Corticium theae, Phyllosphere.

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Pijush Kumar Dutta ¹, B. K. Dutta ¹, A. K. Das ¹, R. C. Sundriyal ¹

Affiliations
1 WWF-India, Western Arunachal Landscape Conservation Programme

Abstract

Alpine timberline, considered to be important ecotone supports rich and highly vulnerable biodiversity and represent one of the most distinct boundaries between forest to tree less alpine areas. It has attracted geographers and ecologist to do research for a long time on the phenomena it encompasses. In recent time, alpine treeline ecotones across most of the world's mountains are being studied because of their potential for monitoring the effects of climate warming on forest ecosystem. Besides, alpine pasture areas in and around timberline zone and commercially important medicinal plants along timberline have also been playing important role as a source of livelihood of mountain communities settled in nearby area. In recent time, with the change in socio-economic aspiration of local mountain communities, there has been a rapid increase in pressure on natural resources in and around timberline area. However, compared to studies of timberline area of European Alps, Andes of South America and mountains of North America, which has reached a very advance stage, very limited studies on timberline of Himalayan mountain range have been carried out. In the present paper, review of timberline research work carried out in the mountain ranges of Europe, North America and Himalaya have been carried out to highlightthe gap in alpine timberline research work in Himalaya.

Keywords

Alpine, Timberline, Ecotone, Biodiversity, Livelihood, Climate Change

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Devashree Yumnam ¹, B. K. Dutta ¹, S. B. Paul ², S. Choudhury ¹

Affiliations
1 Microbial & Agricultural Ecology and Biodiversity Conservation Laboratory, Department of Ecology and Environmental Science, Assam University, Silchar-788011, IN
2 Department of Chemistry, Assam University, Silchar-788011, IN

Abstract

Fipronil is a highly active, broad spectrum systemic pesticide belonging to the phenyl pyrazole group of chemicals. The aim of the present study was to observe the alterations in the surface morphology of erythrocyte membranes of Swiss albino mice exposed to fipronil with the help of scanning electron microscope (SEM) and also its effect on the liver and kidney with the help of transmission electron microscope (TEM). The animals were divided into control group which received distilled water via intraperitoneal injection, and a treated group which received 1/3<sup?rd of LD₅₀ dose of fipronil intraperitoneally, every 24 hours for 30 days. Various types of alterations in the morphology of the red blood cells of the fipronil treated mice were observed. There was decrease in discocytes and increase in the number of echinocytes, spherocytes and ovalocytes. In case of liver, the degeneration of the nucleus, nucleolus, nuclear membrane and mitochondria were commonly observed in all the treatments compared to the control. The cytoplasm was also found to be vacuolated with the breakdown of the organelles. The kidney cells of the treated mice were also observed with different degrees of degeneration. The mitochondria were damaged with destructed cristae surrounded by basal membrane that is disorganized and the nucleus was shrunken with dense chromatin condensation. Presence of vacuoles in the cytoplasm was seen as well as thickening of the glomerular basement membrane was observed.

Keywords

Albino Mice, Electron Microscopy, Erythrocyte Membrane, Fipronil.

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P. Handique ¹, P. Rethy ², B. K. Dutta ³

Affiliations
1 Krishi Vigyan Kendra (A.A.U.), Garumuria, Lakhimpur (Assam), IN
2 Department of Forestry, North Eastern Regional Institute of Science and Technology, Nirjuli (Arunachal Pradesh), IN
3 Department of Ecology and Environmental Sciences, Assam University, Silchar (Assam), IN

Abstract

The present study was conducted in Papum pare district of Arunachal Pradesh and selected 160 bamboo growers covering four circle based on elevation. The mean value of adoption score (41.54) is highest in Balijan followed by Kimin (40.26) and lowest in Sagalee circle (35.39). So, the farmers of Balijan circle are much more advanced in adopting the scientific bamboo cultivation practices as compared to other circles. A positive correlation is found in all socio-economic characteristics except age. The co-efficient of multiple determinations explain that all the six variables in overall sample, jointly contributes 53.65 per cent variation in overall adoption score.

Keywords

Adoption, Scientific, Bamboo, Relationship.

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B. K. Dutta ¹

Affiliations
1 B. E. College, Howrah, IN

Abstract

You have heard the four speakers, who have so lucidly presented their papers, with the help of slides, charts and diagrams. In this connection what I have heard at the initial session may be of interest to you.

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