The effect of plant growth promoting bacteria both in vitro and hydroponic culture of barley (Hordeum vulgare L.) growth

Plant growth promoting bacteria (PGPB) boost plant development and promote soil bioremediation by secreting a variety of metabolites and hormones. Several important bacterial characteristics, such as biological nitrogen fixation, phosphate solubilization, ACC (1-aminocyclopropane-1-carboxylate) deaminase activity, and production of siderophores and phytohormones, can be assessed as plant growth promoting (PGP) traits. In the current study, three Bacillus megaterium strains and one Pseudomonas fluorescens strain have been investigated for their plant growth promoting abilities in vitro and in a hydroponic culture on barley. Firstly, these bacterial strains have been investigated for their salt (NaCl) tolerances and then phosphate solubilization, nitrogen fixation and the production of ammonia and indole-3-acetic acid. These bacterial strains were also inoculated with Hordeum vulgare in a hydroponic culture. The investigated bacterial strains were found to have different plant growth promoting activities even within same species (B. megaterium). In the hydroponic culture experiments, it was determined that comparing to the control group, the growth rates (total weight) of the plants enhanced with B. megaterium (FDG108), B. megaterium (FDG161), and B. megaterium (FDG2) ranged from 3.91, 43.45, and 73.73, respectively. Even these three bacteria were B. megaterium, the best result regarding the total plant weight was obtained with B. megaterium (FDG2). These results showed that even if many bacteria enhance plant growth, the use of better one is of vital importance in agriculture practice for production of food.