Production of plant growth promoting substances by Rhizosphere Microorganisms

Abstract

Summary Different microorganisms belonging to the genera Azotobacter, Bacillus and Streptomyces, isolated from the rhizosphere of common bean and tomato plants, were used to investigate their ability to synthesize plant growth substances. The supernatant of the bacterial cultures showed the presence of a compound with Rf 0.92 which corresponds to indole acetic acid together with unidentified derivatives. These organisms also secreted gibberellins having different Rf values. The spectrum of indoles and gibberellins differed between tested bacterial strains. The elutes of different spots of indoles and gibberellins showed stimulatory effect on the length and dry weight of excised barley roots. The highest response was in the case of indoles having Rf 0.99 and gibberellins having Rf 0.54.