The Study On Different Tolerance And Mechanism Of Cd In Tobacco

This study was conducted on cadmium tolerance differences of 8 varieties of tobacco by combining hydroponic experiment and pot experiment method; through pot experiment on tobacco varieties K326, were studied at different growth stages on the response mechanism of cadmium stress; and the influence on tobacco quality study effect of cadmium on tobacco. The results show that:(1) showed that cadmium stress of different varieties of tobacco seedlings to cadmium absorption and growth of eight varieties of tobacco, absorption of cadmium content increased with increasing cadmium concentration, the cadmium content of yellow neck is the highest, Yunyan 87 Cd was the lowest. The Cd concentration was 5mg/L, root length and plant height increased, the tobacco K326 root length and plant height growth trend is relatively large, when the Cd concentration is 10mg/L, the heavy metal Cd on tobacco seedling root and stem have toxic effects on the growth of root and shoot was inhibited. Compared with the control, root,stem and eight varieties of tobacco seedling dry weight were decreased, which reduce the magnitude of the minimum K326.(2) showed that the effect of different varieties of tobacco topping stage of growth and physiological and biochemical indexes of cadmium stress, different concentrations of cadmium stress in different organs of different tobacco varieties on the uptake and accumulation of cadmium stress:in the low concentration of cadmium (= 2mg/kg), leaf> stem> root; stress in high concentration of Cd (= 20mg/kg), leaf> root> stem. The cadmium content in different organs of all tobacco varieties increased with increasing cadmium concentration, positive correlation. K326 has good resistance to cadmium, cadmium content in leaves of K3263 concentrations of cadmium and other 7 varieties compared to the lowest. Different concentrations of cadmium stress on photosynthetic performance have a greater impact, the differences between different tobacco varieties were. In high concentration under Cadmium Stress, the leaf photosynthetic rate becomes negative,photosynthesis declined sharply, all tobacco varieties have different enzyme activity in leaf decreased, and MDA content increased significantly. Without the addition of cadmium or low concentration, the transpiration rate is higher Yunyan 87;K326 in the cadmium concentration of 20mg/kg was higher in leaftranspiration rate; NC82 concentration of cadmium is 80mg/kg higher when the transpiration rate is high, the better resistance to cadmium.(3) Through the study of cadmium tolerance differences of K326 in different growth stages show, differences of cadmium tolerance of tobacco is different in different growth period of performance. K326, the rosette stage, vigorous seedling growth long-term with cadmium concentration increased first increased and then decreased, while the topping stage showed increased and then decreased at first and then decreased.In the Cd, SOD, CAT, POD play an important role in the antioxidant system of K326, is an important physiological mechanism of K326 resistance to cadmium. Each time the K326 CAT activity was first increased and then decreased. With the increase of cadmium concentration, the activity of SOD also decreased in seedling stage and topping stage, seedling POD activity decreased; while the rosette and vigorous growing stage SOD and POD activity were increased first and then decreased.Under the cadmium stress, the content of MDA K326 in four tobacco breeding period is increased. Also the soluble protein content of K326 in tobacco seedling increased with the increase of cadmium concentration increased, and then decreased at first and then decreased, the rosette stage is at first increased and then decreased, and flourishing and topping stage decreased.(4) Studies show that the difference of tobacco quality of different varieties of cadmium, in low concentration (2mg/Kg) of cadmium stress, although some tobacco varieties of certain individual quality indexes (reducing sugar, nicotine, potassium content) has a good trend, but for other chemical components in tobacco and tobacco quality index index of coordination it is reduced, the formation of adverse effects, and therefore did not improve the quality of tobacco leaves. With the increase of Cd concentration and adverse effects on the chemical composition is also gradually increased, which is not conducive to the formation of tobacco leaf aroma jealous, resulting in reduced tobacco quality and economic benefit.