Physiological responses of peanut seedlings to exposure to low or high cadmium concentration and the alleviating effect of exogenous nitric oxide to high cadmium concentration stress

摘要

The physiological responses of peanut seedlings exposed to low (5 mu M) or high (200 mu M) cadmium (Cd) concentration and the ability of sodium nitroprusside (SNP, a donor of NO) to reverse the harmful effects of Cd on peanut (Arachis hypogaea L.) were studied. Changes in plant growth parameters, chlorophyll content, antioxidant system, nutrient contents and Cd accumulation were investigated. The results showed that SNP and 5 mu M Cd improved plant growth and chlorophyll content. Furthermore, antioxidative system was up-regulated, and as a result, the production rate of superoxide radical (O-2(center dot-)) was reduced. Moreover, the absorption of nutrient elements was not impacted, and Cd toxicity was not observed. However, 200 mu M Cd had negative effects on the above measured parameters and dramatically increased the accumulation of Cd in all the plant organs. In the 200 mu M Cd treatment, addition of 250 mu M SNP stimulated plant growth and increased chlorophyll content. It also enhanced the regulation of antioxidative system and reduced the production rate of O-2(center dot-) and malondialdehyde (MDA) content. Besides, SNP supply enhanced the absorption of nutrient elements and restrained the absorption and transport of Cd.