Moënne-Loccoz, Y., Naughton, M., Higgins, P., Powell, J., O'Connor, B., and O'Gara, F.;

1999

January

Journal of Applied Microbiology

Effect of inoculum preparation and formulation on survival and biocontrol efficacy of Pseudomonas fluorescens F113.

Published

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SUGAR-BEET DAMPING-OFF BRADYRHIZOBIUM-JAPONICUM PYTHIUM-ULTIMUM SEED 2,4-DIACETYLPHLOROGLUCINOL PUTIDA BIOSYNTHESIS METABOLITES SEEDLINGS

86

108

116

Sugarbeet seeds used by farmers are often pelleted using an EB-(TM)-based mis. During the pelleting process, the seeds are dried immediately after application of the mix. In this work, the effects of inoculum preparation and formulation on survival and biocontrol efficacy of Pseudomonas fluorescens F113Rif were investigated using a 1:1 EB(TM)/vermiculite mix and sugarbeet seeds pelleted with this material. Growing F113Rif Cor 3 d (28 degrees C) within the EB(TM)/vermiculite mis amended with nutrients (sucrose asparagine broth), instead of adding the cells to the unamended mix immediately before drying the mis or the pelleted sugarbeet seeds, resulted in improved survival of the strain in the mis or on the seeds, respectively, during subsequent storage. A slower drying (20 h instead of 3 h) of the F113Rif-inoculated EB(TM)/vermiculite mix to 11% w/w water content enhanced strain survival in the mis during storage, bur the drying conditions studied had no effect on inoculant survival on the seed during storage when pelleted seeds were dried to 10% w/w water content. Biological control of damping-off disease of sugarbeet (caused by Pythium spp.) in soil microcosms was achieved when F113Rif was inoculated in the unamended mis 3 d before pelleting the seeds, but not when nutrient-amended mix was used. Inoculum preparation and drying of the formulation are keg factors to consider when optimizing the use of a commercial EB(TM)/vermiculite seed formulation for delivery of a biocontrol Pseudomonas inoculant.