Symbiotic behaviour of phage-resistant mutants of pigeonpea [Cajanus cajan (L.) cv. BaharJ rhizobial strain IHP-195 with the main and alternate hosts

Abstract

The phage-resistant (vr) mutants of an effective rhizobial strain do not retain the symbiotic property as their parent and become either ineffective [1 and2] or partially effective [3] with their original legume host. However, no study has been conducted till date to know the symbiotic behaviour of such mutants with the alternate legume hosts. The rhizobia nodulating pigeonpea belong to the "cowpea miscellany" group, which have a wide host range. In such a situation, curiosity therefore arose regarding the ecological significance of vr mutants. This study was undertaken to investigate the nodulation efficiency and symbiotic effectiveness of vr mutants of pigeonpea rhizobial strain IHP195 with one cultivar each of the original (main) host and five alternate hosts to determine the change in host range nodulation capacity, if any, of a rhizobial strain due to its mutation for phage resistance.