Evaluation of Fluorescent Pseudomonad Isolates for Their Activity Against Some Plant-Parasitic Nematodes

摘要

To evaluate the isolates of fluorescent pseudomonads for biological control of plant-parasitic nematodes including Helicotylenchus indicus, Xiphinema americanum and Meloidogyne incognita. Thirty-seven pseudomonad strains were collected from the rhizosphere of field-grown crop plants and tested under in vitro condition against the nematodes. Three strains were tested against M. incognita on mungbean. Bacterial strains were characterized for the production of siderophores, salicylic acid, 2, 4-diacetylphloroglucinol (DAPG), hydrogen cyanide and extracellular protease. Of the 37 strains, 26 produced siderophores, 14 produced salicylic acid, 7 produced DAPG, 6 synthesized cyanide and 12 produced extracellular protease. Only two strains (CD 38 and CD 62) caused more than 50% mortality of the juveniles of all three nematode species. Seed bacterization with isolates CD 38 and CD 62 did suppress galling due to M. incognita in mungbean roots, reduced nematode populations and enhanced shoot weight. The isolates of pseudomonads differed in the production of secondary metabolites and their nematicidal activity. Fluorescent pseudomonad strains that produce a variety of secondary metabolites possess greater nematicidal potential. Useful data on secondary metabolite production by pseudomonad are provided.