Salicylic acid-mediated alleviation of cadmium toxicity in hemp plants in relation to cadmium uptake, photosynthesis, and antioxidant enzymes

To assess the role of salicylic acid (SA) in alleviating cadmium (Cd) toxicity in hemp (Cannabis sativa L.) plants, the growth parameters, Cd accumulation, photosynthetic performance and activities of major antioxidant enzymes were investigated in hemp seedlings treated with 500 mu M SA, under 0, 25, 50, and 100 mg Cd kg(-1) sands (DW) conditions, respectively. Cd exposure resulted in a small reduction in biomass (12.0-26.9% for root, and 8.7-29.4% for shoot, respectively), indicating hemp plants have innate capacity to tolerant Cd stress. This was illustrated by little inhibition in photosynthetic performance, unchanged malondialdehyde content, and enhancement of superoxide dismutase (SOD) and peroxidases (POD) activities in hemp plants. Cd content in root is 25.0-29.5 times' higher than that in shoot, suggesting the plant can be classified as a Cd excluder. It is concluded that SA pretreatment counteracted the Cd-induced inhibition in plant growth. The beneficial effects of SA in alleviating Cd toxicity can be attributed to the SA-induced reduction of Cd uptake, improvement of photosynthetic capacity, and enhancement of SOD and POD activities.