In order to expand the cultivation of white lupin and improve its nodulation and growth in Tunisian soils, twenty native strains affiliated to the Rhizobium and Agrobacterium genera were used in this study. Phenotypic characterization identified a strain, LAb8, that was highly tolerant of different types of abiotic stress under in vitro conditions, including pH variation (4-11), drought (15-30% PEG600) and salinity (600-1500 mM NaCl). With cultivation in sterilized carrier sand, the nodulation test highlighted the efficiency of this strain in increasing shoot dry weight (+208%) and nitrogen accumulation (+116%) compared to unfertilized control plants. Subsequently, a pot experiment was conducted to elucidate the potential of these selected strains applied as liquid and solid inoculants to promote nodulation and growth, as well as the nitrogen content of white lupin plants grown in non-sterilized soils. The results showed that inoculation with LAb8 significantly increased nodulation in terms of number (+95-118%) and dry weight (213-296%), whether as a solid or liquid inoculant. Significant increases were recorded in inoculated plants for leaf chlorophyll content (+9-11%), plant height (+16-18%), shoot and root dry weight (+38-44% and +51-61% respectively) compared to unfertilized control plants. Interestingly, compared to unfertilized control plants, application of the selected strain induced higher shoot nitrogen accumulation varying from 71% to 79% for liquid and solid inoculants, respectively. Furthermore, the solid inoculant was more efficient than its equivalent, the liquid inoculants gave the best dry nodular biomass and nitrogen content, respectively + (26%) and (+ 5%) respectively than the liquid form.