Effects of different carbon dioxide and LED lighting levels on the anti-oxidative capabilities of Gynura bicolor DC

Gynura bicolor DC is not only an edible plant but also a kind of traditional Chinese herbal medicine. G. bicolor DC grown in controlled environmental chambers under 3 CO2 concentrations [450 (ambient), 1500 (elevated), 8000 (super-elevated) μmol mol−1] and 3 LED lighting conditions [white (WL), 85% red + 15% blue (RB15), 70% red + 30% blue (RB30) ] were investigated to reveal plausible antioxidant anabolic responses to CO2 enrichment and LED light quality. Under ambient and elevated CO2 levels, blue light increasing from 15% to 30% was conducive to the accumulation of anthocyanins and total flavonoids, and the antioxidant activity of extract was also increased, but plant biomass was decreased. These results demonstrated that the reinforcement of blue light could induce more antioxidant of secondary metabolites, but depress the effective growth of G. bicolor DC under ambient and elevated CO2 levels. In addition, compared with the ambient and elevated CO2 levels, the increased anthocyanins, total flavonoids contents and antioxidant enzyme activities of G. bicolor DC under super-elevated CO2 level could serve as important components of antioxidative defense mechanism against CO2 stress. Hence, G. bicolor DC might have higher tolerance to CO2 stress.