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    Evaluation of streptomyces and non-streptomyces actinomycetes isolates for growth promotion in Vigna radiata and their use as biocontrol agent against Sclerotium rolfsii
    (University of North Bengal, 2016-03) Ray, Pushpanjali; Chakraborty, Arka Pratim; Chakraborty, Bishwanath
    Two streptomyces (ARHS/PO26 and ARHS/PO27) and two non streptomyces (ARHS/Mn3 and ARHS/Mn7) actinomycetes isolates obtained from the rhizosphere soil of Solanum tuberosum and Mangifera indica were found to be phosphate solubilizers and showed antagonistic activity against Sclerotium rolfsii. Isolates ARHS/PO26 and ARHS/PO27 were identified morphologically and confirmed by the National Centre for Fungal Taxonomy, as Streptomyces griseus (NCFT 2578.08; NAIMCC-B-00916) and Streptomyces griseolus (NCFT 2579.08). ARHS/Mn 3 and Streptomyces griseolus (ARHS/PO27) could inhibit 68% and 59.7% growth of Sclerotium rolfsii in vitro. In vivo evaluation of the isolates ARHS/Mn 3, Streptomyces griseolus (ARHS/PO27) and Streptomyces griseus (ARHS/PO26) showed maximum growth promotion on Vigna radiata by enhancing key defense enzymes like chitinase, β-1,3-glucanase, phenylalanine ammonia lyase and peroxidase. The results emphasize the fact that soil actinomycetes could be used as potential biocontrol agents.
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    Integrated management of seedling blight disease of tea caused by Sclerotium rolfsi
    (University of North Bengal, 2015-03) Bhagat, Indramani; Chakraborty, Bishwanath
    Tea is one of the important plantation crops in Nepal. One of the important fungal pathogens Sclerotium rolfsii, causing seedling blight disease in tea was found to be predominant in the nursery grown plants. The art and science of plant disease control has moved in the direction of biological control of plant pathogen is a distinct possibility for the future and can be successfully exploited in modern agriculture, especially within the framework of integrated disease management systems. Effective integrated management practices against S. rolfsii were developed using neem cake, oil cake, aqueous leaf extract of Azadirachta indica, bio-control agent like Trichoderma harzianum and calixin (0.1 vi%) in vivo. Combination with cow dung, neem cake, oil cake, chicken manure and rabbit manure, disease reduction were insignificant. However, combination with neem cake and oil cake showed 66.4% disease incidence, whereas in oil cake, neem cake and Azadirachta indica in combination disease incidence were recorded 11.1%. Under pot culture conditions T. harzianum alone and in combination with neem cake, oil cake and Azadirachta indica provided best effective management practices of seedling blight in all the three modes of application viz., simultaneous, repeated and post infection.