Effects of CO2 Concentration and Temperature on Growth Characteristics, Physiological Activities, and Antioxidant Activities of Angelica gigas Nakai

Angelica gigas Nakai is an important medicinal plant. Several environmental factors such as altitude, physiognomy, and atmospheric temperature can affect the cultivation of A. gigas. Therefore, climate change is likely to influence the growth of A. gigas and the synthesis of its active ingredients. This study aimed to investigate the effects of different carbon dioxide concentrations and temperatures according to Shared Socioeconomic Pathways (SSP) scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5) on the growth, physiological activities, and antioxidant activities of A. gigas. The photosynthesis rate of A. gigas under SSP1-2.6 and SSP5-8.5 conditions showed a steady reduction. Chlorophyll a, total chlorophyll, and carotenoid content decreased with the prolongation of the growing season under climate change conditions. Chlorophyll a fluorescence showed significantly higher RC/CSo, RC/ABS, PI_abs, SFI_abs in higher CO₂ concentration and temperature conditions. Only the total dry weight of A. gigas for each climate change scenario was significantly different, while the other growth characteristics were not significantly different because of high inter-individual variation. The antioxidant activities of A. gigas (DPPH, ABTS, and NO scavenging activities) under each of the different conditions showed no significant differences. The reducing power was significantly increased in SSP5-8.5 compared to SSP1-2.6. The differences in phenolic contents of both aerial parts and root parts were not statistically significant, while the flavonoid content of aerial parts increased depending on the temperature and CO₂ concentration. These results indicated that climate change can affect the growth, physiological activities, and antioxidant activities of A. gigas Nakai. Our findings underline the need to develop strategies to overcome the adverse aspects of climate change.