Abstract: We investigated the adaptive characteristics and physiological mechanisms of Pennisetum americanum × P. purpureum and Festuca arundinacea under cadmium (Cd) and nickel (Ni) stresses. Seedling biomass and resistance physiological characteristics of those two species were measured under different concentrations of Cd and Ni. The results showed that the concentrations ranging from 0 to 50 mg·L^-1 of Cd promoted the fresh weight of P. americanum × P. purpureum shoot. At a concentration of 200 mg·L^-1, the seedling biomass of both species decreased significantly. The activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) initially increased and then declined with the increases of Cd concentration. Under Ni stress, the malondialdehyde (MDA) content and superoxide anion content of both species peaked at the concentration of 300 mg·L^-1. The soluble protein content of P. americanum × P. purpureum reached its maximum at the Ni concentration of 300 mg·L^-1, while Festuca arundinacea exhibited the highest soluble protein content at the concentration of 200 mg·L^-1. Principal component analysis and membership function evaluation were employed to analyze the morphological and physiological indices of those two species. The results indicated that P. americanum × P. purpureum exhibited the highest stress resistance under Cd stress, while Festuca arundinacea performed best under Ni stress. Overall, our results provide valuable insights into the potential use of those two species in the phytoremediation of Cd and Ni polluted soils.

Key words: heavy metal stress, herbaceous plant, physiological characteristics, growth inhibition