Effect of Cd Concentration on Cd Content and Growth and Physiological Indices of Tobacco Seedlings

In order to explore the damage mechanism of cadmium(Cd) on tobacco,effects of cadmium with different concentrations on the growth and the physiological and biochemical activities of tobacco were studied by solution culture.The results showed that the growth of tobacco plant was restrained under the cadmium stress.Acetic acid-extractable Cd was the main chemical form of Cd in root system.In leaves,Cd mainly existed in the forms of binding to Acetic Acid and deionized water.With the increase of Cd concentration,Cd tended to transform from low activity to high activity.The Cd content in different parts of tobacco seedlings under different Cd treatment was:stem root leaf.The chlorophyll content,nitrate reductase activity,root activity and MDA content changed under different cadmium treatment to tobacco seedlings.With the increase of cadmium concentration,the dry matter accumulation increased firstly and then decreased,chlorophyll content and root activity showed a gradual decreasing trend,nitrate reductase activity increased firstly and then decreased,and MDA content decreased first and then increased.This study suggest that low concentrations of Cd can stimulate tobacco biological activity,but high concentrations of Cd can significantly inhibite the growth of tobacco seedlings,reduce the physiological activity,and ultimately affect their normal growth.