Effects Of Cadmium Pollution On The Physiological Characteristics Of Flue-Cured Tobacco

Heavy metal pollution is one of the most serious envionmental problems in recent years. Heavy metal pollution in soil degenerates soil fertility, decreases crop yield and product quality,deteriorates water environmentn and endangers human health through food chain. Study on heavy metal pollution became one of the hottest academic areas. The flue-cured tobacco seeding were used to study how the cadmium contamination impacts on antioxidant enzymes,malondialdehyde, photosynthesis system,endochemical hytihomones.The effects of cadmium pollution on antioxidant enzymes in flue-cured tobacco roots and leaves. The effects of cadmium stress on active superoxidedismutase,peroxidase,catalase,ascorbate peroxidase and glutathione reductase in flue-cured tobacco roots and leaves were studied. The results showed that the activities of superoxidedismutase,scorbate,peroxidase and catalase reach maxima in flue-cured tobacco roots when the concentration of the cadmium was at 5mg/l; Antioxidant enzymes activity considerably increased at first,then declined; The activities of peroxidase glutathione reductase reach maxima when the concentration of the cadmium was at 25mg/l,then declined. Malondialdehyde graduately enhanced with the concentrations of the cadmium increasing in flue-cured tobacco roots and leaves; Ascorbateperoxidase,catalase,glutathionereductase reach maxima in flue-cured tobacco leaves when the concentration of the cadmium was at 5mg/l,superoxide dismutase,peroxidasereach maxima when the concentration of the cadmium was at 25mg/l,then declined.The effects of cadmium pollution on photosynthetic apparatus of flue-cured tobacco. The results showed that the content of photosynthetic pigment was declined when the concentration of the cadmium increasing. The study showed that cadmium played an important role of Pn,Gs,Ci,Tr. At the same of,the experiment showed that the lower Fv/Fo,Fv/Fm,ФPSⅡand qP were reduced in flue-cured tobacco leaves under cadmium stress. Above all,cadmium promoted the degradation of chlorophyll and played a certain role in the destruction on the photosynthetic apparatus. The results reduced the potential and efficiency of photosynthesis of flue-cured tobacco leaf under cadmium stress.Cadmium inhibited the synthesis of indoleacetic in flue-cured tobacco roots and leaves and this inhibition increase with increasing in treatment cadmium concentration. Cadmium stimulation the synthesis of GA3 and IAA at lower concentaation,but inhibited the synthesis of GA3 and IAA at higher concentrations. IAA and GA3 reach maxima when the concentration of the cadmium was at 5mg/l. Different cadmium concentrations stimulation the synthesis of ABA in flue-cured tobacco roots and leaves and this stimulation increased with increasing in treatment cadmium concentrations.