Abstract:A pot experiment in growth chamber with two CO2 concentrations (400 μL?L-1 and 800 μL?L-1) were conducted in this study by using seedlings of superior clone of Cunninghamia lanceolata“Yang 061” to investigate the effects of CO2 enrichment on seedlings growth, roots morphology, photosynthetic physiology, and nutrient concentration of C. lanceolata seedlings, and to explore the response characteristics of superior clone of C. lanceolata to elevated CO2 concentration, and ultimately providing theoretical basis for high-quality and efficient cultivation of C. Lanceolata seedlings. The results showed that: 1) CO2 enrichment significantly promoted the biomass accumulation and the height growth of C. Lanceolata seedlings, and significantly promoted the roots growth as well, the roots length, roots surface area, roots volume and roots diameter under CO2 enrichment treatment were 14.60%, 28.26%, 41.98% and 14.70% higher than that in control. 2) CO2 enrichment significantly increased the carotenoid content in leaves of C. Lanceolata seedlings, and this was also true for net photosynthetic rate (Pn), intercellular CO2 concentration (Ci) and water use efficiency (WUE), which were 51.03%, 14.13%, and 151.20% higher in CO2 enrichment treatment as compared with control, respectively, while stomatal conductance (Gs) and transpiration rate (Tr) were decreased by 58.72% and 44.00%, respectively, when compared with control. 3) CO2 enrichment significantly increased the maximal fluorescence (Fm), variable fluorescence (Fv), PSⅡpotential efficiency (Fv/Fo), PSⅡ actual photochemical efficiency (ΦPSⅡ) and photochemical quenching coefficient (qP), which were 11.48%, 11.25%, 6.33%, 20.38% and 30.34% higher than that in control, respectively, while non-photochemical quenching coefficient (NPQ) were significantly decreased by 21.90%, and no significant difference was observed in initial fluorescence (Fo) and PSⅡ maximal photochemical efficiency (Fv/Fm) between treatments. 4) CO2 enrichment significantly increased plant calcium concentration, while significantly decreased plant phosphorus concentration. Taken all these results together, our results showed that short-term CO2 enrichment can promote the growth of C. Lanceolata seedlings by increasing photosynthetic pigments content and net photosynthetic rate and light use efficiency in leaves, which resulted in a higher photosynthetic capacity, and by promoting the growth of roots, which in-turn enhanced plant nutrient uptake capacity.