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Researcher Padder, Shahid Ahmad
Advisor Dar, G. H.
Source KrishiKosh-Indian National Agricultural Research System
Content type Text
Educational Degree Doctor of Philosophy (Ph.D.)
Publisher SKUAST Kashmir
File Format PDF
Language English
Subject Domain (in DDC) Natural sciences & mathematics ♦ Plants (Botany) ♦ Specific topics in natural history
Subject Keyword Bacterial Diversity ♦ Brown Sarson ♦ Endophytes ♦ Optimization ♦ Ammonia Production ♦ Iaa ♦ Chitinase ♦ Carbon Sources ♦ Nitrogen Sources ♦ Plant Pathology ♦ Plant Pathology Bacterial Diversity Brown Sarson Endophytes ♦ Diversity of Bacterial Endophytes of Brown Sarson (brassica Rapa L.) Roots and Their Efficacy As Potential Bioinoculants In Organic Agriculture Under Kashmir Conditions
Abstract The present study was aimed to assess the diversity of bacterial endophytes of brown sarson (Brassica rapa L.) as well as their efficacy as potential bioinoculants in organic agriculture under temperate conditions of Kashmir. The root samples of brown sarson were collected from three districts of the valley viz., Anantnag, Srinagar and Baramulla. The survey revealed that bacterial population was highest (4.4 × 105 cfu/g of fresh weight) at site Hugam (Anantnag) and lowest (7.0 × 103 cfu/g of fresh weight) at site Nowgam (Srinagar). Eighty one morphologically dissimilar isolates were selected and characterized on the basis of Gram’s staining and cell and colony morphology. Gram negative bacteria were most predominant. The colony characterization revealed that circular forms dominated. Likewise the colonies with entire margins and convex elevation were pre-dominated amongst the isolates. The isolates were screened for temperature and drought tolerance and various metabolic properties, optimization and plant growth promoting attributes. The metabolic properties of isolated bacterial root endophytes revealed that all the isolates metabolized glucose and galactose but some isolates did not metabolize maltose and sucrose. Drought tolerance studies revealed that all the bacterial isolates grew at all the PEG concentrations tested. Amongst the isolates only 28 isolates produced ammonia with average production of 31.76 µg/ml. The isolates with > 25 µg ammonia/ml were optimized using yeast extract as a nitrogen source in place of peptone. All the isolates were screened for indole acetic acid (IAA) production and it was observed that forty four isolates produced IAA with average production of 8.15 µg/ml. The isolates with the IAA production of > 9 µg/ml were optimized using L-tryptophan supplementation. The screening for chitinase activity revealed that only 22 isolates produced chitinase enzyme with average production of 15.83 units/ml. The isolates with chitinase activity >15 units/ml were optimized using various carbon source (1%) under varied incubation periods. Experiment on phosphate solubilization revealed that 31 isolates released free phosphate from tri-calcium phosphate with average release of 95.88 mg/l. The isolates with activity > 90 mg/l were optimized using different nitrogen source (1%) supplementations at varied incubation periods. The screening for siderophore activity revealed that only 22 isolates had siderophore producing ability with average siderophore production of 12.81 (% siderophore unit). The antifungal behaviour of isolates revealed that only 25, 21, 17 and 18 isolates inhibited Dematophora necatrix, Pythium aphanidermatum, Fusarium oxysporum and F. solani, respectively. The assay on hydrogen cyanic acid in terms of absorbance revealed that only 15 isolates produced HCN. The overall performance of all the isolates was quantified by giving the weightage to each attribute of plant growth promotion and 12 isolates most promising ones were selected for pot house studies. The inoculation of effective isolates showed insignificant impact on soil pH but significant on EC against control. The soil enzymatic activities viz., dehydrogenase, protease, phosphatase, cellulase, xylanase, urease and amidase in endophyte inoculated soils showed significant change. The plant macro- and micro-nutrient and leaf pigments also increased in inoculated treatments. The yield attributes of brown sarson showed significant increase in inoculated treatments as compared to uninoculated control. All the twelve isolates were identified on morpho-biochemical and physiological basis as per the Bergey’s Manual of Determinative Bacteriology. Of these isolates six best ones were identified using 16s rRNA gene sequencing and it was observed that all the six isolates were six dissimilar strains and were identified as Bacillus subtilis strain smppsap1, Bacillus subtilis strain smppsap2, Pseudomonas lutea strain smppsap3, Pseudomonas fluorescens strain smppsap4, Pseudomonas fluorescens strain smppsap5 and Bacillus pumilus strain smppsap6. All the sequences were submitted to GenBank NCBI, USA and accession numbers were obtained.
Educational Use Research
Education Level UG and PG
Learning Resource Type Thesis
Size (in Bytes) 15.23 MB