Isolation and Screening of Plant Growth-promoting Rhizobacteria (PGPR) Isolates Across Different Seasons in South Gujarat, India

Plant Growth Promoting Rhizobacteria (PGPR) a major constituent of Rhizobacteria, encourage the plant growth through their diverse mechanisms. In this investigation, 33 different Isolates were isolated from the rhizosphere soils of various research stations in south Gujarat were screened for their plant growth promoting activity. All the 33 tested isolates in pre monsoon and post monsoon were evaluated and documented various PGPR activities. Thirteen isolates of pre-monsoon season and twenty isolates of post monsoon season selected for further study. Based on colonial characteristics and morphology of isolates, 33 were selected for Siderophore, HCN, IAA production phosphate solubilizing and antagonistic activities. Among 33 isolates, 10 isolates showed phosphate solubilizing properties, 10 isolates had Siderophore production, 6 isolates had IAA activity and no one organism produced HCN. All the isolates were found to have nitrogen-fixing potential. Among these, those isolated before the monsoon season have more number of Gram positive bacteria while those isolated post monsoon were Gram positive as well as Gram negative.