Growth rates of Rhizobium trifolii and Rhizobium lupini in sterilized soils

Abstract

The growth characteristics of Rhizobium trifolii and R. lupini in a sterilized infertile sandy soil were studied at different temperatures. R. trifolii grew at a faster rate than R. lupini at all temperatures up to 30°C. The optimum temperature for growth for both species was found to be approximately 30°. Temperatures higher than 35° were found to be lethal for both species, the cells of R. trifolii being the more sensitive. In a fertile sandy loam the growth rates of both species were improved, the effect being more pronounced with R. lupini. The presence of the appropriate host plants in the sterilized infertile sand resulted in faster growth rates in both species, particularly R. lupini.