Abstract: In order to study the influence of exogenous nitrogen on the production of arginine generated by arbuscular mycorrhizal（AM） fungi in leguminous plants， a pot culture experiment was carried out. Phaseolus radiatus L. was used as the host plant with inoculation of AM fungi and/or rhizobium. Exogenous nitrogen including 4 mmol·L-1 NH4Cl， 4 mmol·L-1 NH4NO3， 4 mmol·L-1 urea and 4 mmol·L-1 Arg were adopted in this pot experiment. It was shown that the arginine concentration in the mycorrhizal roots was highest， when Arg was supplied with AM fungi or double inoculation， which was 247 and 320 mg·g-1， respectively， and the latter was significantly higher than the former. But， arginine production was not influenced with rhizobium inoculation. With double inoculation， the mycorrhizal infection rate， chlorophyll content， nodule number and weight and the total uptake of nitrogen were significantly increased compared with AM fungi inoculation. And， the effects of NH4NO3 were the best among all kinds of tested exogenous nitrogen. It was concluded that the double inoculation was more beneficial for the absorption of nitrogen and growth of plants.

Key words: arbuscular mycorrhizal fungus, Rhizobium leguminosarum, Phaseolus radiates L., arginine, nitrogen