Suppression of root rotting fungi and root knot nematode of chili by Seaweed and Pseudomonas aeruginosa

Abstract

Solvent fractions (i.e. n-hexane, chloroform and methanol) of the ethanol extracts of the seaweeds Codium iyengarii, Jania capillacea, Stokeyia indica and Solieria robusta caused more than 50% mortality of Meloidogyne javanica juveniles within 24 h at 10 mg/ml. Nematode mortality increased with an increase in fraction concentration or exposure time. The n-hexane fractions from S. indica, J. capillacea and C. iyengarii and the chloroform fraction from S. robusta also resulted in more than 50% mortality within 48 h at 1.0 mg/ml. In a screen-house experiment application of S. indica and S. robusta as soil amendments alone or with Pseudomonas aeruginosa, a plant growth promoting rhizobacterium (PGPR), significantly suppressed infection of chili roots by root-infecting fungi Macrophomina phaseolina, Rhizoctonia solani, Fusarium solani and the root knot nematode Meloidogyne javanica. Seaweed alone or with PGPR also increased plant growth. Suppressive effect on root pathogens and growth enhancement potential of seaweeds and P. aeruginosa were also effective in field plots. © 2008 Blackwell Verlag.