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Subject: Nematology × Author: Basumatary, Binita × Start date: 2010 × Type: Thesis ×
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    ThesisItemOpen Access
    ISOLATION, CHARACTERIZATION AND EVALUATION OF ENDOPHYTIC BACTERIA AGAINST ROOT-KNOT NEMATODES
    (AAU, Jorhat, 2020-09) Basumatary, Binita; Das, Debanand
    Fifteen endophytic bacteria were isolated from leaves and stems of Solanum lycopersicum and S pimpinellifolium. Morphological characterization of these endophytes revealed that 6 bacteria were gram positive and 9 bacteria were gram negative, 10 bacteria were rod shaped, 3 were coccus shaped and 2 were diplococcus in shape. All 15 bacteria were motile in nature. Biochemical characterization of the isolated endophytes revealed that 9 bacteria showed positive reaction to KOH test while, 6 were negative to KOH test, 11 bacteria showed positive reaction to Citrate and 4 were negative to citrate test. All the 15 bacteria were positive for Gelatine hydrolysis and Catalase test. Six endophytic bacteria showed positive reaction and 9 showed negative reactions for Starch hydrolysis test. Four potential isolates were structurally analysed by using scanning electron microscope and revealed that the length and breadth of BETLI, BETL2, BETL4 and BETS2 were 701.70nm × 348.30nm, 954.l0 nm x 303.10 nm, 984.10nm × 332.90nm and 1422.00nm × 742.00 nm, respectively. Five endophytic bacteria showing potentiality against root-knot nematode were identified by using 16S rRNA, and they were Microbacterium arborescens (BETLI), Bacillus marisflavi (BETL2), Bacillus altitudinis (BETL4), Exigobacterium indicum (BETS2) and Bacillus marisflavi (BETL6). Study on in vitro efficacy of bacterial endophytes against second stage juvenile of root-knot nematode (J2) revealed that all the isolates had the potentiality to significantly increase the mortality of nematodes however, the isolate BETL2 showed the best result on mortality rate (81.47%) of 2 stage juvenile (J2) of Meloidogyne incognita, followed by isolates BETL4 (81.43%) and BETLI (79.07%) Dose-response models were used to determine the concentration of bacterial culture filtrates required to kill 50 per cent juveniles of M. incognita. Four potential bacterial endophytes were tested with different methods of applications (seed treatment, seedling root dip treatment, soil application and their combinations) in pot condition against root-knot nematodes in tomato. All the tested endophytic bacteria significantly increased the plant growth parameters of tomato and reduced the nematode multiplication than untreated control. However, maximum increase in plant growth parameters and decrease in number of galls, egg mass and nematode population in soil was observed in combined application of seed treatment + root dip treatment + soil treatment of Bacillus marisflavi (BETL2) @ 1x 10 cfu/ml of crop.