Rhizobacteria cooperative effect against Meloidogyne javanica in rhizosphere of legume seedlings

Summary Root-knot nematodes are major pests of legume fields in Iran. This research evaluated the effect of Rhizobium leguminosarum bv. phaseoli and Pseudomonas fluorescens CHA0 (stand alone and combination treatment) on galling and reproduction of root-knot nematode, Meloidogyne javanica, in legum (chickpea, bean, lentil, pea) seedling rhizosphere, and the growth properties of the host plants. The legumes seeds were sown in 1kg sterilized sandy loam soil. Inocula were 5 J2/g of soil, in the case of the nematode, while considering the bacteria 1×107 cfu/kg soil. A treatment of nematicide (cadusafos) was performed, as a commonly used nematicide in Iran, at 2g/kg soil. Two months after inoculation, the following parameters were recorded: the number of knots, egg masses and reproduction factor of the nematode, bacterial nodules per root, and growth properties of seedlings in the treatments (control, nematode, nematode+nematicide, and nematode+rhizobacteria). The greatest bacterial effect on the control of the nematode was observed in the rhizosphere of the bean treatments. Inoculation with Rhizobium in the soil decreased the galling on the legumes’ roots, and the combined inoculation with Pseudomonas and Rhizobium resulted in a higher decrease of the galling.