Effects of peanut rhizobia on the growth and symbiotic performance ofArachis hypogaea under abiotic stress

The effects of saline and osmotic stress on four peanut rhizobia, plant growth and symbiotic N2-fixation inArachis hypogaea were studied. Abiotic stress was applied by adding either 100 mM NaCl or 20 mM PEG6000. At the rhizobial level,Bradyrhizobium ATCC10317 and TAL1000 showed stronger tolerance to stress than TAL1371 and SEMIA6144. The effect of salinity on the bacterium-plant association was studied by using the variety Blanco Manfredi M68. In the absence of stresses, all the strains induced a significantly higher number of nodules on the roots, although TAL1371 and SEMIA6144 were more effective. Both stresses affected the interaction process, while TALl371 was the best partner.