Abstract

The aim of the present study was to evaluate indigenous PGPR (Plant growth promoting rhizobacteria) previously isolated from Argentina's soybean fields for their in vitro antagonistic effects on the control of Fusarium tucumaniae and F. virguliforme, in two separated in vitro assays. In assay 1, the bacteria that showed the highest significant (P < 0.05) F. tucumaniae mycelial growth inhibition were strains Bacillus subtilis 54 (70%), B. cereus 13 (44%), B. cereus 7 (44%) and Chryseobacterium vietnamense 110 (42%). Despite their antagonistic activity, the strains identified as Stenotrophomonas malthophilia and B. cereus were not included in any further experiments, because of their potential hazard. In assay 2, strains 54, 110 and Pseudomonas fluorescens 9 and 115 were tested against F. tucumaniae and F. virguliforme. In this study, native bacterial strains isolated from Argentine Pampas were tested for the first time against these pathogens. All four bacterial strains significantly inhibited mycelial growth of F. virguliforme. Further studies on the effects of these strains on the growth of soybean plants and on the Sudden Death Syndrome (SDS) control will uncover the mechanisms and in vitro antagonism potential of these bacterial isolates.

Key words: Antagonism, plant growth promoting rhizobacteria (PGPR), Fusarium, Pseudomonas, Bacillus, Chryseobacterium vietnamense.