Survival of several Rhizobium/Bradyrhizobium strains on different inoculant formulations and inoculated seeds

• Published in: International microbiology 2002-06, Vol.5 (2), p.81-86
• Main Authors: Temprano, F J, Albareda, M, Camacho, M, Daza, A, Santamaría, C, Rodríguez-Navarro, D Nombre
• Format: Article
• Language: English
• Subjects: Biotechnology - methods; Bradyrhizobium - growth & development; Bradyrhizobium - physiology; Insecticides; Rhizobium - growth & development; Rhizobium - physiology; Seeds - microbiology; Soil Microbiology; Temperature
• ISSN: 1139-6709
• DOI: 10.1007/s10123-002-0067-y

The effect of a variety factors on the survival of several rhizobia strains on inoculants and inoculated seeds has been evaluated. Since the rhizobia strains showed different cell-density-evolution patterns on peat-based inoculants and on inoculated seeds, several inoculant formulations with highly effective Rhizobium/Bradyrhizobium strains (for Lupinus, Hedysarum, Phaseolus and Glycine max.) were monitored under the following storage conditions: (a) the inoculants were kept refrigerated (at 4 degrees C), or (b) at room temperature (25 degrees C). The effect of water content (30-50%, w/w) in the inoculants as well as that of several seed-coating adhesives were also investigated. Alternative carriers including perlite and vermiculite were tested. For all of the strains, survival on sterile peat-based inoculants was higher than on the corresponding unsterile peat formulation; for the latter, refrigerated storage conditions are recommended to ensure high bacterial densities. The water content of the inoculants had a differential effect on strain survival depending on the sterility of the peat, such that a high water content was more detrimental when unsterilized peat was employed. The best adherent for rhizobia survival was a gum arabic/water solution. Perlite was as effective as peat in maintaining a high population of rhizobia, at least for 6 months of storage.