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Theses

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2000 - 200972010 - 20163
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Subject: Plant Pathology × End date: 2016 × Thesis Type: Ph.D ×
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Now showing 1 - 9 of 10
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    ThesisItemOpen Access
    MOLECULAR CHARACTERIZATION OF FEW PLANT GROWTH PROMOTING MICROBES, THEIR COMPATIBILITY ANALYSIS AND UTILITY IN BIOINTENSIVE MANAGEMENT OF BACTERIAL WILT OF TOMATO
    (AAU, Jorhat, 2015) Nath, Bharat Chandra; Bora, L. C.
    Biointensive management of bacterial wilt of tomato (Lycopersicon esculentum Mill) caused by Ralstonia solanacearum was attempted using various bioactive (Plant Growth Promoting) microorganisms viz., Trichoderma viride, Pseudomonas fluorescens, Bacillus subtilis and Azotobacter chroococcum. The molecular characterization of these microorganisms was made to determine their distinctiveness from their close relatives through sequencing of ITS region of ribosomal DNA in case of fungal microorganisms and 16S region of ribosomal DNA in case of bacterial microorganisms. Interactive action among the four bioactive microorganisms showed compatibility in all the treatment combinations in vitro. The antagonistic potential of these bioactive microorganisms was tested in vitro singly or in consortia and per cent inhibition of target pathogen were recorded and analyzed. The highest inhibition (57.70%) against R. solanacearum was recorded against consortia of T. viride+ P. fluorescens + B. subtilis + A. chroococcum followed by T. viride + P. fluorescens + B. subtilis (39.77%) and P. fluorescens + B. subtilis + A. chroococcum (35.65%). Talc based bioformulations were prepared using the best three bioactive microorganisms and their consortia for management of bacterial wilt in pot grown tomato plants during 2013-14 and 2014-15 crop seasons. Applications of the consortial formulations were made as seed treatment, root treatment and soil application. Significantly highest reduction of bacterial wilt incidence (95.09 %) and highest yield (1.692 kg/plant) of tomato was recorded in treatment comprising of T. viride+ P. fluorescens + B. subtilis + A. chroococcum. Correlation studies revealed negative correlation (-0.993) between bacterial wilt incidence and yield of tomato. Screening of 47 tomato genotypes was done under field condition during 2012-13 and 2013-14 crop seasons to assess their degree of tolerance against bacterial wilt pathogen R. solanacearum. Highly resistance reaction (HR) was recorded in Konbilahi (L. pimpinellifolium) followed by resistance reaction (R) in Sel-35, sel-19 and Sel-9. Highest yield was recorded in 2012/TOLCVRES-3 (278.16 q/ha) followed by H-24 (276.85 q/ha) and 2012/TOLCVRES-4 (272.04 q/ha).
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    ThesisItemOpen Access
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    ThesisItemOpen Access
    Studies On Rice Tungro Virus Disease With Special Reference To Some Biochemical Changes
    (Assam Agricultural University; Jorhat, 2000) Nath, Phuleswar; Bhagabati, K. N.
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    ThesisItemOpen Access
    Studies On The Incidence And Management Of Culm Rot And Bamboo Blight Disease
    (Assam Agricultural University; Jorhat, 2006) Borah, Rajib Kumar; Puzari, K. C.
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    ThesisItemOpen Access
    Occurrence And Significance Of Vesicular Arbuscular Mycorrhizal (Vam) Fungi In Tea Garden Soils Of Assam
    (Assam Agricultural University; Jorhat, 2000) Hazarika, Dilip Kumar; Phookan, A. K.
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    ThesisItemOpen Access
    Management Of Bacterial Wilt Of Tomato Through Bioagents And Host Resistance
    (Assam Agricultural University; Jorhat, 2002) Kalita, Bhaben Ch.; Bora, L. C.
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    ThesisItemOpen Access
    Further Approach To The Integrated Management Of Sclerotinia Sclerotiorum (Lib.) De Bary - The White Rot Pathogen
    (Assam Agricultural University; Jorhat, 2002) Kakoti, Raaj Kumar; Saikia, U. N.
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    ThesisItemOpen Access
    Identification And Management Of Spawn Contaminants And Insect Enemies Of Oyster Mushroom
    (Assam Agricultural University; Jorhat, 2002) Mazumder, Nirmal; Rathaiah, Y.
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    ThesisItemOpen Access
    Carpogenic germination of Sclerotia of Sclerotiniasclerotiorum (Lib.) de Bary and development of an IDM modules for management of Sclerotinia rot of French bean
    (AAU, 2015) Lalfakawma, C.; Das, B.C.
    Studies conducted on morphological and pathogenic variability among 30 isolates of Sclerotiniasclerotiorum (Lib) de Bary, derived from infected French bean (Phaseolus vulgaris) plants showing typical symptoms of white mold, collected from different geographical location of NE. All the isolates showed variation in morphological characters based on their mycelial growth, colony character and sclerotial formations. Out of 30 isolates, 14 isolates showed highly virulent reaction, each of 8 isolates revealed moderately and less virulent reaction respectively on French bean. HPLC analysis of mycelial culture extracts of highly, moderately and less virulent isolates from S. sclerotiorum showed that higher number of phenolic acid and higher concentration of oxalic acid were observed in highly virulent isolates of S. sclerotiorum , while lowest number of phenolic acids and least conc. of oxalic acid detected in less virulent isolates. In in vitro study of growth of highly virulent isolates of S. sclerotiorum against fungal antagonists showed that T. harzianum caused maximum inhibition of radial growth of S. sclerotiorum among the antagonists. Maximum growth and least per cent inhibition of radial growth by different antagonists was observed in AS3 (Assam) isolate of S. sclerotiorum. Effect of burial depth, soil drenching with Carbendazim and mycoparasites on carpogenic germination of Sclerotia of S. sclerotiorumwere evaluated under pot condition. It was observed that higher number of apothecia were produced when Sclerotia placed at ‘0’cm depth, while no apothecia were found at deeper depths viz,.6, 8 and 10cm respectively. Soil application of Carbendazim were more effective when applied 10 days after burial as compared to application at ‘0’ day of burial in inhibition of carpogenic germination of Sclerotia and there was a decreased sclerotial germination with increased concentration of fungicide. Amongst the antagonists, T. harzianum was found to be the most effective agent and caused highest reduction in carpogenic germination of Sclerotia followed by G. virens and T. koningii respectively. Under field condition, maximum reduction of white mold incidence and higher growth response and yield were observed when seeds were treated with Carbendazim @ 0.2% and it was integrated with soil application of T. harzianum @ 2%(w/w) of soil and Carbendazim spray @ 0.1% at 15 and 30 DAG in FYM amended soil as compared to other treatment combinations.