Abstract: The study showed that under Pinus sylvestriformis seedlings,the amount of rhizosphere soil bacteria,but not fungi and actinomyces,increased significantly (P≤0.001) with CO₂ enrichment (700 and 500 μmol·mol^-1),and the same (P≤ 0.001) was under Pinus koraiensis seedlings,with the exceptions of 700 μmol CO₂·mol^-1 in August and 500 μmol CO₂·mol^-1 in July,compared to the ambient chamber and the ambient in each month.No significant effect of elevated CO₂ was found on the amount of rhizosphere soil fungi except in September (P≤0.01),and the response of actinomyces to elevated CO₂ was also insignificant.

Key words: Zea mays L., Sulfate supply, Nitrogen, Metabolism, N-S interaction, Roots vigor