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Subject: Microbiology × Author: Chopra, Gourav × Start date: 2019 × Type: Thesis ×
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    ThesisItemOpen Access
    Evaluation of silicate solubilizing bacteria and fly ash application on rice (Oryza sativa L.) crop
    (Chaudhary Charan Singh Haryana Agricultural University hisar, 2022-09) Chopra, Gourav; Leela Wati
    Fly ash has been reported beneficial for soil and plant health as it can act as soil conditioner and has varying amount of different nutrients required for plant growth. Use of chemical fertilizers for agriculture in present time has become a serious threat for environment and sustainability, therefore use of fly ash in agricultural system can reduce the demand of chemical fertilizers. Fly ash used in present study was of grey colour, sandy texture and alkaline pH. Different plant nutrients i.e. nitrogen phosphorus, potassium were detected in trace amount whereas silicon was present in high concentration. Total 52 bacterial isolates were screened for silicate solubilization on Bunt and Rovira medium out of which 40 bacterial isolates (SSB1-SSB40) showed clear zone and highest silicate solubilization index (2.67) was observed for isolate SSB2. Six bacterial isolates (SSB2, SSB6, SSB17, SSB26, SSB30 and SSB32) exhibiting high silicate solubilization were tested for different plant growth promoting traits. All bacterial isolates were able to produce indole acetic acid and excrete ammonia in the range of 5.72-12.40μg/mL and 1.75- 4.60μg/mL, respectively. Three bacterial isolates (SSB2, SSB6 and SSB30) were found positive for siderophore production. Bacterial isolates SSB2 and SSB32 have shown growth in nutrient medium having 10% NaCl concentration. Highest silicate solubilization (36.69 mg/L and 23.98 mg/L) was exhibited by SSB2 after 21 days in liquid medium having 0.25% magnesium trisilicate and 0.25% fly ash, respectively. Optimum concentration of fly ash to be amended in liquid medium was found 0.35% as amendment of 0.45% fly ash resulted decreased silicate solubilization by bacterial isolates. On the basis of biochemical characterization and partial 16S rDNA sequencing the isolate SSB2 found promising under in vitro studies was identified as Pseudomonas baetica. The viable count of bacterial culture SSB2 in nutrient broth amended with different concentrations of fly ash increased upto 3% fly ash and hampered with further increase in fly ash concentration and increased incubation period. Survival of bacterial culture enhanced on fly ash amended in soil from 0.5-3% whereas it was impeded by further increase in concentrations. Under pot house conditions, amendment of fly ash (3%) in soil along with RDF and treatment of rice seedlings roots with bacterial culture SSB2 resulted in improved plant growth and grain yield in comparison with control.