Responses of Angelica acutiloba Kitagawa Transplants to Elevated Ambient CO2 Concentration

Long-term exposure to an elevated ambient carbon dioxide (eCO2) concentration could weaken or diminish the enhancement of plant photosynthesis and growth. To monitor this response and offer references for growth management, the whole-plant photosynthetic rate (Pn,w) and dark respiration rate (Rd,w) of Angelica acutiloba Kitagawa transplants were monitored with a growth chamber. The results showed that eCO2 increased both the Pn,w and Rd,w by (79 ± 42) % and (126 ± 51) %. The dry weight of transplants under eCO2 was 33.6% greater than that under aCO2. However, the photosynthetic acclimation to eCO2 occurred. The increase in the Pn,w was maintained until the end of the experiment due to increased leaf area. Moreover, the increase in plant dry weight mainly occurred in the first 15 days of treatment. Furthermore, the dry weight estimated based on the Pn,w and Rd,w agreed well with the measured dry weight. The relative growth rate (RGR) calculated with the estimated dry weight demonstrated the response of transplant growth to eCO2. These results indicated that the proposed method can be used to monitor the response of plant growth to eCO2.