The Effect Of Amendments On Absorption Of Cd And Uptake And Growth Of Tobacco

In this study,the effects of the Cd on the seed germination and seedling growth were studied.The effects on the passivation of Cd and the effect on tobacco plants during the whole growth and development by different biochar and soybean was found by pot experiment.Aim to provide the theoretical basis for the control of Cd in tobacco in our province.The main findings are as follows:(1)Cd pollution has a toxic effect on tobacco seeds.The results showed that with the increase of Cd concentration,the germination potential,germination rate,germination index,vitality index of seeds and the height of tobacco seedling were inhibited.The bud poisoning mortality rate of more than 50%when Cd 10 mg/L.(2)Under Cd stress,the growth of tobacco seedling was inhibited,and the degree of inhibition was increasing with the increasing concentration of Cd stress.Chlorophyll content was significantly reduced,seedling growth is getting worse,root shoot ratio gradually become smaller,inhibit the healthy growth of tobacco seedlings.(3)Under Cd stress,the antioxidant enzymes in the seedlings were destroyed,enzyme activity was uncoordinated,and the physiological processes were disturbed,leading to tobacco seedling damage.CAT activity,SOD activity and soluble sugar content were increased first and then decreased,POD activity,MDA content,free proline content and Cd content in tobacco leaves increased with the increase of Cd concentration.(4)Under Cd stress,the growth and development of tobacco plants were inhibited.Under different amendments,the plant height,leaf number,maximum leaf length,maximum leaf width,stem circumference,dry matter accumulation,root shoot ratio have different degrees of increase of tobacco plants grown in different concentrations of Cd soil,can reduce the Cd stress on the inhibition of tobacco plants,and promote the growth and development of tobacco plants.(5)Different amendments can relieve the damage of antioxidant enzymes in tobacco plants by Cd stress.Chlorophyll content and CAT activity were increased.POD activity,Pro content and MDA content were decreased.SOD activity was decreased when Cd<5 mg/L and increased when Cd 10 mg/L.When Cd≤2 mg/L,the content of soluble sugar decreased and when Cd≥5 mg/L,soluble sugar content increased.(6)The Cd content in tobacco leaves increased with the increase of Cd concentration.During the whole growth and development period,the change trend of Cd content decreased first and then increased.When the amendments was applied in the soil,the Cd content in the tobacco leaves can be reduced,which indicates that the amendments can reduce the Cd in the tobacco.(7)Under Cd stress,the chemical composition of tobacco leaves tends to be uncoordinated and is not conducive to the formation of high quality tobacco leaves.When the amendments were applied in the soil,the content of total nitrogen,protein content,total sugar content,reducing sugar content were decreased.Nicotine content,starch content were increased,making shmuck value,sugar nicotine ratio,nitrogen base ratio decreased,K/Cl increased.(8)The distribution of Cd in tobacco plants was root<stem<upper leaves<middle leaves<lower leaves.When the amendments were applied in the soil,the Cd content was decreased and the absorption of Cd was reduced in the tobacco leaves.(9)Two kinds of amendments and different proportions have different effects on the absorption of heavy metals from tobacco leaves.The comprehensive performance of 0.5%biochar is better than 0.1%biochar,and 0.5%soybean is better than 0.1%soybean.