KAUR, MOHINDERRATHORE, ROHIT2017-01-192017-01-19201047134http://krishikosh.egranth.ac.in/handle/1/97030Abstract Under the present study the aim was to isolate and identify and select native plant beneficial fluorescent Pseudomonas sp. producing antifungal activity from apple and pear growing in normal and replant sites of Chamba district. They all were also screened out for the production of other direct and indirect plant growth promoting activities viz; siderophores, HCN, Ammonia, P-solubilizing, lytic enzymes, in vitro and plant growth regulators viz; auxins, gibberellins, and cytokinins, so as to select potential strains to be further developed and used as inoculants for management of replant problem of apple and pear. Almost all the ten isolates of Pseudomonas sp. showing antifungal activity against Fusarium oxysporum (27.5 to 48.2% growth inhibition), Dematophora sp.(38.4 to 56.9%) and Pythium sp. (33.3 to 53.3%), except two isolates, (AR-4-Cha and AN-2-Cha) did not show inhibitory activity against Pythium sp. All isolates showed production of siderophores (16-20 mm, diameter of yellow zone) and 21.42 to 47.61% siderophore unit), P-solubilizing activity (15 to 23 mm diameter of yellow zone and (27 to 87 μg\ml available orthophosphate) HCN and ammonia (++ to +++++), lytic enzymes proteases (15-21 mm dia of clear zone) and plant growth regulators ie auxins (7-30 μg\ml), gibberellins (21-60 μg\ml) and cytokinins (80-150 μg\ml). Ethyl acetate extracted antifungal metabolites from acidic supernatant of all the isolates of fluorescent Pseudomonas sp. showed inhibition of growth of mycelia of Fusarium oxysporum (46.5 to 55.1%), Dematophora sp. (44.6 to 56.9%) and Pythium sp. (40.0 to 48.3%) on malt extract agar. All the exttact also showed siderophore activity on and in CAS agar and broth in the range of 15 to 22 mm dia. of yellow\orange zone and 8.47 to 28.81%SU. Thin layer chromatographic analysis of extracted antifungal metabolites showed Rf value in the range of 0.68 to 0.76 and development of orange spot after spraying with P-anisaldehyde reagent. Also UV-Visible spectrum of all extract showed maximum absorbance at 270nm. According to literature it was concluded that all the extracted antifungal metabolites may belongs to group of broad spectrum antibiotic i.e. 2,4-diacetylphloroglucinol, which is effective in controlling the soil borne root diseases of plants.enThesis