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

Abstract

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.

Diversity of native rhizobia isolated in south Brazil and their growth promotion effect on white clover (Trifolium repens) and rice (Oryza sativa) plants

“…Antoun et al (1998) reported that non-leguminous plants react to the presence of bradyrhizobia and rhizobia on their rhizospheres; however, the growth-promoting effect depended on the bacterial strains isolated and their endogenous PGP abilities (Galleguillos et al 2000;Vessey 2003). In our study, the environment proved to be a very important component for plant growth promotion using rhizobia inoculation because several rhizobia isolates promoted the plant growth in sterile conditions, but they were unable to reproduce the same effect in non sterile, rich nutrient conditions (Table 6; Temprano et al 2002;Bennett et al 2003). This observation can be attributed to bacterial persistence and competition in the soil and to the amount of nutrients present in very rich soil conditions (Hagen et al 1997;Krasova-Wade et al 2006;Al-Khaliel 2010;Costa et al 2013).…”

Advances in plant growth-promoting bacterial inoculant technology: formulations and practical perspectives (1998–2013)

“…The procedure is laborious because of large volume; there is high energy cost; it is time consuming, and most importantly, some organic materials change their chemical properties and may produce toxic substance to some bacteria during autoclaving. Still, autoclaving is favorable for several rhizobia strains that survive in sterile peat inoculant far better than under non-sterile conditions (Temprano et al 2002).…”

Aplicações da biodiversidade bacteriana do solo para a sustentabilidade da agricultura

“…Biopolímeros (polivinil álcool -PVA, polivinil pirrolidona -PVP, polietileno glicol -PEG, bem como o alginato, a goma xantana e o amido); são adicionados para neutralizar compostos tóxicos, como os compostos fenólicos liberados na rizosfera (TITTABUTR et al, 2007). Também possuem uma boa ligação com a água e atuam como agente hidratante; além de melhorar a adesão das células microbianas à semente (TEMPRANO et al, 2002). 3.…”