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20111
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Subject: Plant Pathology × Author: Anjali Thakur × End date: 2011 × Start date: 2011 × Type: Thesis × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    EVALUATION OF Pseudomonas fluorescens AS BIOCONTROL AGENT TO CONTROL BACTERIAL BLIGHT IN BASMATI RICE
    (Punjab Agricultural University, Ludhiana, 2011) Anjali Thakur
    Bacterial blight caused by Xanthomonas oryzae pv. oryzae is one of the most devastating disease in south-east Asia including India. Fluorescent pseudomonads have been successfully employed in controlling major plant diseases due to their antimicrobial metabolites. The present study focuses on isolation, characterization, in-vitro, in-vivo evaluation and rhizosphere competence of Pseudomonas fluorescens. Isolations were done from the rice and wheat rhizosphere which were identified on the basis of cultural characters and molecular markers. It was found that the isolates showing fluorescent characteristics in the selective media showed the amplification of the targeted ITS region. In-vitro evaluation by dual culture method revealed that isolate Pf-4-R was inhibitory to the test pathogen showing maximum inhibition zone of 5.5 mm. The result was supported by the use of phl gene specific primers and HPTLC based method characterizing the production of antimicrobial compound DAPG. Isolate Pf-4-R was also found to have stimulatory effect on germination and radical elongation. Talc based powder formulation of the effective isolate Pf-4-R was prepared for further evaluation. Pot-house and field evaluation revealed that seed treatment and root dip and post-inoculation foliar spray significantly reduce the disease showing least disease index (25.6%) and maximum disease suppression efficiency (62.4%). Rhizosphere competence was studied by raising rifampicin (rif) resistant mutant, it was found that once introduced bioagent was able to establish in the root zone effectively and maintained its count for whole of the crop season. Shelf life of the formulation was studied at room temperature and low temperature, it was found that bacterium remained viable and at optimum number for 60 days in the formulated product and storage at low temperature was more effective as compare to room temperature.