Two laboratory and greenhouse experiments were conducted to study the
efficiency of six Rhizobium meutot; isolates (2. 4. 11. 12 and 15) and strain ARC·1
isolated from witd alfalfa plants of salt affected soil to symbiotic performance with 5
varieties alfalfa (Medicago sativa) plants (Ismailia 1. Ismailia 2, Nitrogen fixers, Diablo
and EI.Wady EI-gedid): in two soli types. The results showed that, all isolates withstand high concentration of NaCI
more than strain ARC-1. Isolate No.15 was the most resistant one to 7.5% NaCI and
different antibiotics concentration. The data of symbiotic parameters showed that. the highest values of
nodules number, nodules dry weight and N2-ase activity on plant roots were found
with plants inoculated with slrein ARC-1 in two soil types. Also isolate No. 12
recorded the highest shoots dry weight and N-conlent in two soils. The superior
interactions were found between ARC·1 and Ismailia 1 for nodulation status and
isolate No. 12 and Nitrogen fixers variety for shoot dry weight and N-content.