Production of Rhizobium Inoculants for Lupinus nootkatensis on Nutrient-Supplemented Pumice

• Published in: Applied and Environmental Microbiology
• Main Authors: Einarsson, Sigurbjorn, Gudmundsson, Jon, Sverrisson, Halldor, Kristjansson, Jakob K., Runolfsson, Sveinn
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Society for Microbiology 1993
• Subjects: Iceland
• Online Access: http://dx.doi.org/10.1128/aem.59.11.3666-3668.1993; https://journals.asm.org/doi/pdf/10.1128/aem.59.11.3666-3668.1993

The use of the legume Lupinus nootkatensis as a pioneer plant to fight soil erosion and to reclaim eroded soils in Iceland has been under development for a few years. Production of a robust, low-cost bacterial inoculant was therefore a prerequisite for the extended use of this plant. Volcanic pumice is a naturally expanded mineral which is available in vast amounts in Iceland. It was tested as a carrier for solid fermentation of Rhizobium lupini. Nutrient-supplemented pumice containing a small percentage of peat and diatomaceous earth and kept in sterile plastic bags promoted good growth of the bacteria. Viable-colony counts remained stable at 10 8 to 10 9 /g for at least 35 weeks when the carrier was stored at 22°C. The pumice-based inoculant had good storage and handling properties and could be mixed directly with the seeds during the sowing process. When seeds of L. nootkatensis were sown manually into nutrient-poor eroded sandy soils, about 56% of the first-year plants were successfully nodulated.