Factors Allecting Rhizosphere Colonization of Tomato Plant by Plant Growth Promoting Rhizobacteria

Abstract

Rhizosphere is defined as “the zone of soil immediately adjacent to legume roots that supports high levels of bacterial activity’’ The goal of this study was to enhance or improve the colonization of rhizosphere of tomato plants by plant growth promoting bacteria. PGPR has two main mechanisms to improve colonization of rhizosphere , first the direct mechanism that improve growth of plant and including the production of phytohormones and nitrogen fixation, and the indirect mechanism which decrease the harmful effects of the growth of pathogens by the production of antibiotics and synthesizing of the lytic enzymes. During this study, 12 bacterial strains were obtained from the rhizosphere of tomato. The greenhouse experiment indicated that the treatment with Ser, B63, E31 had shown good capacities for tomato root colonization. To improving the survival rate of tested bacterial isolates, micro- encapsulation techniques of rhizosphere microorganisms by sodium alginate and calcium chloride was conducted. The survival rate of bacteria in capsules was estimated during one month shelf life experiment. Both tested methods free bacterial cells as well as encapsulation technique are promising tools to be used as successful delivery methods of plant growth promoting bacteria