Tamilvendan, K.PRAVEEN KARIJADAR2023-05-092023-05-092023-02-24Th-13613https://krishikosh.egranth.ac.in/handle/1/5810197182Microbial biofilms are organized surface-associated microbial cells enclosed in a matrix of hydrated exopolysaccharides (EPS). EPS produced by biofilm-forming rhizobacteria prevent desiccation by forming hydrophilic biofilms on root surface, which impede the flow of water and enable solubilization of various plant nutrients. Exploitation of these bacteria with plant growth promoting (PGP) traits assumes greater significance in promoting crop production under stressful conditions such as moisture stress. Therefore, it was hypothesized that inoculation of biofilm-forming PGP rhizobacteria improves growth, yield, soil available major nutrients and nutrient uptake in chilli under drought stress in greenhouse conditions. Rhizospheric bacteria were isolated from soils collected from different dry zones of Karnataka. Out of 64 rhizobacteria isolated, 21 isolates were confirmed as biofilm formers as determined by in vitro qualitative and quantitative assays. In vitro evaluation of these isolates for PGP activities and induced moisture stress tolerance using PEG-8000 (35%) yielded two efficient isolates KLB-9 (Lysinibacillus xylanilyticus) and BGK-4 (Enterobacter cloacae subsp. dissolvens as identified by 16S rRNA sequencing). These two isolates recorded aminocyclopropane-1-carboxylic acid (ACC) deaminase activity; improved chilli seed germination at 20% PEG (Polyethylene glycol) under in vitro conditions. Greenhouse studies conducted with these isolates along with the reference bacterium Pseudomonas fluorescens under 50 and 100% field capacity revealed that L. xylanilyticus significantly improved plant growth, physiological parameters, plant biomass, soil nutrient content and nutrient uptake in chilli under induced drought stress at 50% compared to uninoculated control and P. fluorescens under greenhouse conditions. Hence, L. xylanilyticus has the potential to act as a bio-inoculant for chilli under droughtstress conditions.EnglishThesis