Abstract: The effects of different levels of Cu²⁺ were studied individually on the growth of two Rhizobium strains and host plant growth,nodulation(%) and nitrogen fixation activity in A.auriculaeformis under solution culture conditions so as to explore a probability of utilization of the genus Acacia in revegetation of Cu²⁺-contaminated land.The results shows that Rhizobium sp.(Acacia auriculaeformis)had more stronger tolerance to Cu²⁺ iron than Rhizobium sp(Lespedeza formosa).The values of EC₅₀ respectively achieved 0.129mmol for Rhizobium sp.and 0.151mmol for the N₂-fixation activity.When the concentration of Cu²⁺ was over 0.50 mmol,N₂-fixation activity had been inhabited thoroughly.Although the formation of nodules of Acacia auriculaeformis could continued,the growth of host plant had been inhibited with the appearance such as stunting,chlorosis. Between the noinodulating but adding nitrogen treat group and the inodulating without any nitrogen resource treat group, when Cu²⁺<0.125mmol, the latter group showed better growth for A. auriculaeformis. There were higher contents of Cu in the underground tissues than in aboveground tissues.

Key words: Cu, Rhizobium sp, Acacia auriculaeformis, Growth, Formation of nodules, N₂-fixation activity, seedling emergence, morphological plasticity, shade, Chinese fir, biomass allocation, natural regeneration