Biocontrol of Meloidogyne graminicola using rhizobacteria on rice seedlings

Abstract

The potential of seven rhizobacterial strains to prevent attacks of rice cv. Basmati-370 seedlings by the rice root-knot nematode, Meloidogyne graminicola, was evaluated in screenhouse tests. In in planta tests, all the rhizobacteria were found to possess significant activity against M. graminicola. Seed inoculation with Gluconacetobacter diazotrophicus Co99-70 was the most effective in preventing J2 penetration, by up to 92%. Bacillus sp. RKB-91, G. diazotrophicus Co99-70 and Pseudomonas sp. RKP-33 were highly effective in reducing galling severity (by more than 80%) and in lowering nematode multiplication. These bacteria also promoted root and shoot growth of seedlings. In an in vitro test, exposure to culture supernatant of G. diazotrophicus Co99-70, Pseudomonas sp. RKP-33, and Bacillus sp. RKB-91 significantly delayed and decreased egg hatching and irreversibly inactivated motility of infective juveniles of the nematode by 64%, 89% and 77%, respectively, within 24 h of exposure.