Temperature tolerance and effectiveness of Rhizobium strains infecting pigeonpea (Cajanus cajan L.) host

Abstract

Nineteen Rhizobium and Bradyrhizobium strains isolated from pigeonpea and screened for their ability to grow at high temperature in liquid medium showed that the optimum temperature of growth for 7 strains was 30°C and for 5 strains 37°C. Other strains like PP 1008, PH 8866, PH9038 and PP309 were able to grow under a wide range of temperatures up to 42°C. A thermotolerant variant of strain PP2015-1 was able grow up to 44°C, although the optimum temperature remained the same as that of the parent strain. No correlation could be observed between thermotolerance of a strain and its efficiency with the pigeonpea host grown in the range of 35 to 42°C