Effects of some Rhizobium strains on chickpea growth and biological control of Rhizoctonia solani

Rhizoctonia solani is one of the most important soil-borne fungal pathogens that attack the roots of plant and causes significant damage to different plants particularly to chickpeas (Cicer arietinum L.). The aim of this work is to study the antagonistic activity of different Rhizobium strains against R. solani in dual culture in vitro and under greenhouse conditions. The benefits of rhizobial inoculant in nitrogen fixation, phosphorous uptake and on plant growth promoting were demonstrated with 42 Rhizobium strains. Among the 42 strains tested, 24 isolates had effective control on R. solani in vitro. In order to study the biological control mechanisms, the Rhizobium strains ability to produce volatile compounds and to solubilise phosphate were investigated. The results showed that 10 strains were able to solubilise phosphorus and 13 strains produced volatile compounds. In pot trials, the percentage of chickpea plants inoculated with different rhizobia showed significant reduce of root rot symptoms compared to the control growing in uninoculated soil. Among these rhizobiums, the strain S27 proved efficient against the soil borne pathogen in vitro and in pot experiments. Our study suggested that inoculation with specific Rhizobium exerts significant disease suppress against R. solani in controlled conditions.