Effects of Carrier and Temperature on Survival of Rhizobium spp. in Legume Inocula: Development of an Improved Type of Inoculant.

The effects of inoculant carrier, temperature, and storage period on the survival of Rhizobium strains were determined by plate count and most-probable-number analyses. Preliminary experiments showed that survival of rhizobia was affected by each of these factors and their interactions. Results of further studies indicated that six strains of rhizobia survived better at high temperatures when lyophilized and suspended in an oil carrier as compared to finely ground peat. The oil base inocula contained ca. 10 viable rhizobia per g after 56 days of incubation at 60 degrees C, whereas peat base inocula contained </=10 rhizobia per g. These results suggest that an oil carrier will protect rhizobia from rapid death at usually lethal high temperatures.