The effects of high temperatures on certain root-nodule bacteria

Abstract

Rhizobia present in soils from western New South Wales and from the New England Tableland were subjected to a series of high temperature survival tests. Rhizobia present in air-dry soils survived temperatures higher than would be experienced under natural conditions. In moist soils the tolerance of medic rhizobia to high temperatures was much lower.

Strains of Acacia, Lotus and Psoralea rhizobia from western New South Wales survived higher temperatures than strains from the New England Tableland, but the tolerance to high temperatures of medic rhizobia did not vary with source. This suggests an ecological adaptation of the three native strains not found in the introduced Medicago rhizobium.