To evaluate the effect of plant growth promoting microbial strains were tested under in vitro condition. The microorganisms work by multiple mechanisms, such as nitrogen fixation, phosphate solubilization, zinc solubilization, IAA production and siderophore biosynthesis etc. are responsible for the plant growth promotion and increased yield. These microbial isolates in production of phytohormone i.e., IAA and Phosphorus solubilization the strain Bacillus megaterium was found superior, which was followed by Pseudomonas striata and Trichoderma viride. Higher production of siderophore by the strain Pseudomonas fluorescens which was followed by Pseudomonas striata. Higher zinc solubilization observed with Pseudomonas striata followed by Bacillus megaterium and Trichoderma viride. In field conditions when guava plant or row treated with RDF+ Pseudomonas striata showed significant superiority in terms of number of fruits per plant, average fruit weight, yield and improved quality which was followed by RDF+ Trichoderma viride and RDF + Bacillus megaterium.