Effects of cadmium stress on growth and physiological and biochemical characteristics of creeping bentgrass

The physiological and biochemical response of creeping bentgrass to cadmium stress were studied in the present study. The results showed that cadmium stress exhibited inhibitory effects on creeping bentgrass initial growth and the inhibition effects increased with the cadmium ion concentration increased. When cadmium ion concentration was 50 mgL-1, seed germination rate, shoot length, root length and seedling fresh weight were 47%, 87%, 54% and 83% of that of control, respectively. Seed germination was completely inhibited by 400 mgL-1 cadmium. Cadmium ion had significant effects on contents of chlorophyll, malonaldehyde(MDA) and activities of superoxide dismutase(SOD), peroxidase(POD). With cadmium ion concentration increased, chlorophyll content decreased whereas MDA content increased gradually. When cadmium ion was 200 mgL-1, chlorophyll content and MDA content were 37% and 864% of that of control, respectively. SOD activity reached maximum of 1 314 Uh-1g-1 with lower cadmium ion concentration of 50 mgL-1. SOD activity decreased with higher cadmium ion concentration although it was still higher than the control. POD activity had similar variations with SOD activity and reached maximum of 225 Us-1g-1 with lower cadmium ion concentration of 100 mgL-1. The response of the 90 day old plants germinated from seeds treated with cadmium (2~100 mgL-1) was similar with seedlings. With cadmium ion concentration increased or cadmium stress period extended, chlorophyll content decreased whereas MDA content increased gradually and both SOD and POD activities increased first and then decreased.