Plant Growth Promoting Activities of Some Rhizosphere Bacteria and their Effect on Brassica rapa Growth

The necessity to develop economical and eco-friendly technologies is steadily increasing. Plant growthpromoting rhizomicrobial strains PGPR are a group of microorganisms that actively colonize plant roots andincrease plant growth and yield. Pot experiments were used to investigate the potential of some rhizobacterialstrains to enhance the Brassica rapa growth. Microbial strains were successfully isolated from the rhizosphereof Panax ginseng and characterized based on its morphological and plant growth promotion characters. Surface disinfected seeds of Wisconsin Fast B. rapa were inoculated with the selected PGPR microorganisms. The different pots treatments were inoculated by its corresponding PGPR (107 cfu mL-1) and incubated in thegrowth chamber at 25°C and 65% RH, the light period was adjusted to 24 hours (day). NPK chemical fertilizerand trade product (EMRO, USA) of effective microorganisms as well as un-inoculated control were used forcomparison. Plants harvested in 40 days were found to have significant increase in leaf chlorophyll units andplant height and also in dry weight of root and shoot in the inoculated seedlings. Root and shoot length and alsoleaf surface area significantly were increased by bacterial inoculation in sterile soil. The study suggests thatRhodobacter capsulatus and Azotobacter chroococcum are beneficial for B. rapa growth as they enhancegrowth and induced IAA production and phosphorus solubilization. This study presents some rhizomicrobialstrains that significantly promoted growth of Wisconsin Fast Plant B. rapa in pot experiment under differentsoil conditions. KCI Citation Count: 1