In order to evaluate nitrogen fixation ability and nutrients uptake in three cultivars of common bean (Phaseolus vulgaris L.) inoculating with some types of inoculants containing different strains of Rhizobium leguminosarum; bv. phaseoli an experimental design was conducted in Khoramdarah region in 2006 and 2007. In this investigation three types of biological fertilizers including Rb117, Rb123, Rb136 and a commercial inoculants (Rhizobean super plus) with two treatment N100 (use of 100 Kg nitrogen/ha) and control (without seeds inoculated and fertilizer) and three common bean cultivars including COS16, Derakhshan and Akhtar (red skin) were used. The experiment was factorial in a randomized complete block design. The strains were provided by Soil and Water Research Institute Laboratory. Rb117 strain showed 58 percent increase in seed yield compared to non inoculants treatment. Among inoculants, the effect of Rb123 strain was 32% compared to others. The highest rate of nitrate reductase enzyme activity was at fertilizer treatment (100 Kg net N per ha) as 1099.18 n mol/g FW/h and the lowest enzyme activity was observed at control (720.3 n mol /g FW/h). Influence of inoculants on potassium and phosphorus absorption by plant, was significant. The highest means were obtained in inoculants treatments. The strain of Rb117 was more effective on common bean compared to other strains. In three cultivars, the COS16 was successful compared to other cultivars. High seed yield and many evaluated traits achieved by COS16 (spotted bean), second year of experiment and Rb117 strain.

Key words: Common bean varieties, Inoculants, RB117 and COS 16, Seed yield