Elevated CO and nitrogen addition have minimal influence on the rhizospheric effects of Bothriochloa ischaemum.

The influence of elevated CO and nitrogen (N) addition on soil microbial communities and the rhizospheric effects of Bothriochloa ischaemum were investigated. A pot-cultivation experiment was conducted in climate-controlled chambers under two levels of CO (400 and 800 μmol mol) and three levels of N addition (0, 2.5, and 5 g N m y). Soil samples (rhizospheric and bulk soil) were collected for the assessment of soil organic carbon (SOC), total N (TN), total phosphorus (TP), basal respiration (BR), and phospholipid fatty acids (PLFAs) 106 days after treatments were conducted. Elevated CO significantly increased total and fungal PLFAs in the rhizosphere when combined with N addition, and N addition significantly increased BR in the rhizosphere and total, bacterial, fungal, Gram-positive (G), and Gram-negative (G) PLFAs in both rhizospheric and bulk soil. BR and total, bacterial, G, and G/G PLFAs were significantly higher in rhizospheric than bulk soil, but neither elevated CO nor N addition affected the positive rhizospheric effects on bacterial, G, or G/G PLFAs. N addition had a greater effect on soil microbial communities than elevated CO, and elevated CO and N addition had minor contributions to the changes in the magnitude of the rhizospheric effects in B. ischaemum.