TRIVENI, SHEMA, G2020-07-272020-07-272018D10,257http://krishikosh.egranth.ac.in/handle/1/5810149899Rice (Oryza sativa L) is the world’s most important staple food for two-thirds of the human population, especially in Asia. In India, 65 % of the population depends on rice as their staple food. Increases in the demand for rice, as a result of increase in population, creates the need to improve rice productivity. Application of plant growth promoting associative bacteria which can be a potential option for enhancing growth and yield of rice in sustainable manner. Plant growth promoting endophytic bacteria (PGPEB) are those bacteria living within plant tissues without causing any visible symptoms and increase plant growth by production of various plant growth hormones, phosphate solubilizing activity, nitrogen fixation and biocontrol activity. Present investigation was carried out to isolate and characterize PGPEB of rice. A total of 149 endophytic bacterial isolates were isolated from four rice genotypes collected from IIRR, Rajendranagar, Telangana. The isolates were purified, colony characters were recorded. The genotype BPT 5204 supported significantly higher mean endophytic bacterial population of 5.34 log CFUg-1 root among the genotypes while the lowest population was observed in IRGC 1220 (4.95 log CFUg-1root). All the 149 isolates were screened for nine PGP activities under in vitro conditions. No isolates among the 149 isolates produced hydrogen cyanide (HCN), which is proven biocontrol activity. Results revealed that among 149 endophytic isolates, 81.20 % isolates produced IAA, 34.89 % isolates solubilized phosphorous, 67.78 % isolates solubilized zinc, 40.93 % isolates solubilized potassium, 44.29 % produced siderophore, 44.29 % isolates were antagonistic against Rhizoctonia solani and 52.34 % isolates were antagonistic against Pyricularia oryzae. One isolate from each media having highest PGP activity score were selected for further evaluation through germination and seedling vigour studies. Compatibility test between bacterial isolates revealed that all the isolates were compatible against each other without inhibiting the growth of other endophytic isolates. Nine endophytic bacterial isolates which increased the vigour index of plants when compared to un-inoculated control were selected for pot culture studies. The nine isolates BN5, IN6, BT1, ST11, IT9, BR1, BRen1, BM3, MA1 were further evaluated as a consortia under pot culture studies. Bacterial consortium consisting nine best isolates (2.8 × 108 CFU ml-1) was used to treat rice seeds (MTU 1010) for pot culture study. Endophytic bacterial consortia significantly improved rice growth parameters like germination, plant height, root length, seedling biomass and number of tillers per plant. The plant growth parameters at 90 DAT were significantly higher in the treatment consisting of bacterial consortium + organic fertilizer + 75% RDF when compared to untreated control demonstrating the ability of saving in fertilizer application. The nine promising isolates were characterized morphologically and biochemically (IMVIC tests, oxidase test, catalase test, carbohydrate utilization test, starch hydrolysis and gelatin liquefaction) and by molecular characterization through sequencing of 16S rRNA gene. Based on the sequencing, the endophytic isolates were identified as Bacillus altitudinis (BN5), Bacillus altitudinis (IN6), Agrobacterium fabrum (BT1), Enterobacter cloacae (ST11), Agrobacterium fabrum (IT9), Bacillus altitudinis (BR1), Agrobacterium fabrum (BM3) and Halobacillus sp., (MA1). The isolate BRen1 was unidentified because of lack of BLAST hits and could be a novel bacterium. Based on the results obtained in the present study, the consortia of endophytic bacteria with multiple plant beneficial activities when formulated into a bioinoculant can serve as cost effective, ecofriendly bioproduct that can also help in minimising chemical application in rice production.ennullThesis