Abstract
Faba bean is a one of the most important legumes grown in world. This study uses several phenotypic markers to classify rhizobia strains isolated from root nodules of Vicia faba in different regions of Tunisia. Characterization resulted in identifying novel symbiotic traits which assimilate 20 biochemical substrates. The new Rhizobium strains had a high capacity of tolerance to salinity constraint and pH variation. Our results show that all the isolates were able to fix atmospheric nitrogen and demonstrated a high potential of phosphorus solubilization. Results also showed that rhizobia isolated from faba bean nodules in Tunisian areas were phenotypically different. Physiological traits indicated a wide diversity amongst the rhizobia studied. Numerical analysis of the phenotypic characteristics categorized the 50 strains into three distinct groups. The adopted approach of identification and selection of local rhizobium strains tolerant to abiotic stress, for their efficiency to fix atmospheric nitrogen and to solubilize inorganic phosphorus can improve the production and use of biofertilizers as inoculant for subsumable agriculture.