Colony-Forming Capacity and Rhizosphere Competence of Pseudomonas fluorescens Strains as Biocontrol Agents in Wheat

Abstract

Rhizosphere-associated beneficial bacteria play an important role in suppressing soil-borne pathogens and promoting plant health in cereal production systems. The present study evaluated the colony-forming capacity and rhizosphere competence of different Pseudomonas fluorescens strains as potential biocontrol agents in wheat cultivation. Selected bacterial strains were assessed under laboratory and greenhouse conditions to determine their ability to colonize wheat roots, survive in the rhizosphere, and establish stable populations under varying environmental conditions. Colony-forming units were quantified periodically from rhizosphere soil and root samples to evaluate bacterial persistence and colonization efficiency. The results demonstrated significant variation among P. fluorescens strains in their rhizosphere competence and population establishment. Certain strains exhibited strong root colonization ability, rapid population growth, and prolonged survival within the wheat rhizosphere. Effective colonization was associated with enhanced competition for nutrients and ecological niches, contributing to suppression of soil-borne pathogens. Greenhouse experiments indicated that highly competitive strains improved plant growth, root development, and seedling vigor while reducing disease incidence in wheat plants. The production of antimicrobial metabolites, siderophores, and plant growth-promoting substances likely contributed to the biocontrol activity and ecological fitness of the bacterial strains. Environmental factors including soil moisture, temperature, and root exudate composition influenced bacterial survival and colonization dynamics. Strong rhizosphere competence was identified as a critical characteristic determining the effectiveness of P. fluorescens as a biological control agent. The findings provide valuable insights into microbial interactions within the wheat rhizosphere and support the development of sustainable disease management strategies utilizing beneficial rhizobacteria for improved wheat productivity and reduced dependence on chemical pesticides.