Abstract: In order to study the effects of cadmium (Cd) stress on antioxidant capacity of Dendrobium officinale, experiments of response relationship between Cd stress and superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) in D. officinale leaves were done, and dynamics equation of SOD, CAT, POD activities based on logistic function were established. The results showed that there was a positive correlation between the SOD, CAT, POD activities and Cd concentration, and the antioxidant capacity was increased when treated by certain Cd concentration. The model parameter calculation displayed that the fitting degree of 12 model under different stress level were fine (R²>0.9, P<0.05). The model parameter calculation indicated that Cd concentration was positively correlation with the intrinsic rates, while negatively correlated with the environmental capacity and inflection points. Comprehensive D. officinale growth period and all inflection points showed that the limit Cd concentration was 2 mg·L^-1 which could improve antioxidant accumulation. Thus, low concentration of Cd stress not only had low toxicity to D. officinale, but also could increase the antioxidant accumulation to a certain extent. Dynamic model based on logistic function with Cd concentration could be a potential tool for predicting the dynamic process of D. officinale growth under Cd stress.

Key words: Dendrobium officinale, cadmium stress, antioxidant enzyme, dynamics model