Management of Meloidogyne incognita in cotton, using strains of the bacterium Gluconacetobacter diazotrophicus

Abstract

Seven strains of the bacterium Gluconacetobacter diazotrophicus (formerly Acetobacter diazotrophicus) were assessed for their antagonistic efficacy against root-knot nematode (Meloidogyne incognita) infecting cotton in vitro and in planta. Cell free culture supernatant of the seven strains of G. diazotrophicus reduced egg hatching by more than 95% and exhibited a paralyzing effect on the infective juveniles of M. incognita within 24 hours. All the strains were found to excrete ammonia and volatile fatty acid during growth. Greenhouse screening of the bacterial strains indicated that all except strain 35-45 significantly enhanced the growth of nematode-infected cotton plants. These strains also reduced nematode multiplication to various extents, ranging from 36 to 69%. Evaluation of the two most effective strains in the field for three years revealed that strain 35-47 persistently and significantly increased cotton yield and reduced root-knot index. Strain Co 99-70, although found to be effective in the greenhouse, failed to produce responses in the field.