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Subject: Microbiology × Author: Manjeet × End date: 2018 × Start date: 2016 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Evaluation of bacterial isolates from shisham (Dalbergia sissoo) rhizosphere for antagonistic activity against Fusarium oxysporum and Ganoderma lucidium
    (CCSHAU, 2017) Manjeet; Pathak, D.V.
    Dalbergia sissoo Roxb. next to teak (TectonagrandisL.f.), is the most planted tree in South Asia . Timber of D. sissoo finds multipurpose uses in different fields and has a high economical impact on many South Asian countries. The species occurs naturally on the reverine forests mostly in association with Acacia catechu. Hence the most suitable site for its growth is sandy and alluvial soil on the banks of rivers and streams. Dalbergia sissoo, an important tree of tropical region, is grown as monoculture or in Agroforestry system because of the quality of its wood and its effect on soil fertility through N2 fixation. Shisham mortility is spread throughout the shisham zone, more severe in the eastern Uttar Pradesh, Bihar, Panjab and Haryana in India. It is highly susceptible to a disease called wilt caused by fungi which target particular species. Two pathogens have been found responsible for shisham mortality - Fusarium sp. dalbergiae causing vascular wilt and Ganoderma lucidium causing root rot. The former was found wide spread throughout shisham growing area whereas G. lucidum is associated in drier localities such as Haryana and Punjab. There are several PGPR inoculants currently commercialized that seem to promote growth through at least one mechanism; suppression of plant disease (termed “Bioprotectants”), phytohormone production (termed “Biostimulants”), or improved nutrient acquisition (termed “Biofertilizers”). These bacteria are also capable to suppress the growth of deleterious microorganisms by production of siderophores, β 1,3 glucanases, chitinases and antibiotics. Keeping in view, the economic importance of shisham and to understand the role of PGPRs for control of wilt disease and promotion of plant growth, the present investigations were conducted. Eighteen bacterial isolates were screened for antagonistic activity against F. oxysporum and G. lucidium in vitro conditions. Five cultures showed prominent activity against the test pathogen. These cultures were also characterized for HCN production, Siderophore formation and Chitinase activity. On the basis of antagonistic activity against two test pathogens and biochemical characterization; five best cultures were identified as SD-25, SD-30, SD-87, SD-97 and SD-99. Maximum seed germination (100%) in vitro was observed in the treatment having (SD-99 only); followed by SD-99+ G. lucidium. These cultures were also tested for plant growth parameters in Dalbergia sissoo. Under pot house conditions isolate SD-99 showed maximum shoot dry weight (0.463g) and root dry weight (0.228g). This culture showed ninety nine percent similarity to Bacillus sp. strain A2733 on the basis of 16s rRNA sequencing.