AimsThe interaction between nitrogen (N) availability in the soil, rhizobia nodule formation and leaf physiological traits of Robinia pseudoacacia L. was explored at initial nodule development.MethodsWe selected two Robinia provenances, one from Northwest (GS) and one from Northeast China (DB), and cultivated seedlings in the greenhouse with and without rhizobia inoculation at normal and high N supply in the soil. After ca. 2.5 months growth, nodule formation, plant biomass, CO2 and H2O gas exchange of the leaves, and foliar N contents and partitioning were analyzed.ResultsRhizobia inoculation strongly promoted the formation of root nodules independent of N availability in the soil, but this effect was more pronounced in the DB than for GS provenance. It reduced biomass accumulation of the GS provenance, but not for DB provenance at both, normal and high soil N availability. High N supply did not affect biomass accumulation independent of rhizobia inoculation. Leaf photosynthesis of both Robinia origins was enhanced by high N supply, but this effect was counteracted by rhizobia inoculation only in leaves of DB plants. In GS but not in DB plants, high N supply reduced not only nodule formation, but also stomatal conductance, but still enhanced transpiration without modifying the foliar water content. In addition, high N supply plus inoculation enhanced the organic N content in GS plants rather than DB plants.ConclusionThese results indicate that excess N availability in the soil interacts with the performance of Robinia provenances, as previously reported for drought and phosphorus (P) depletion.