Variability in individual nodule activity of single strains of Rhizobium etli and R. tropici in symbiosis with Phaseolus vulgaris

Abstract

A green-house experiment in Leonard jars was conducted to study the variability of nitrogenase activity (acetylene reduction) of individual nodules of Phaseolus beans inoculated separately with 19 strains of Rhizobium tropici and 6 strains of R. etli. Both species showed a wide range of activities with a C.V.=80% for R. tropici and C.V.=70% for R. etli. These data indicate that Rhizobium species with reiterated nif genes may present similar variability of single nodule activity as Rhizobium species containing a single copy of nif gene and that the use of either R. tropici or R. etli may be used for inoculant production with precaution for loss of effectiveness.