Research On Absorption,Accumulation And Reduction Of Heavy Metal Cadmium In Tobacco

Using Yuyan 12 as tested variety,the combination of pot experiment with field application was designed in Wangyu test station of Zhangzi County in Shanxi province from 2013 to 2015 to study the rules of absorption and accumulation of tobacco to cadmium and the reducing effects of biochar to cadmium in tobacco.The growth and physiological indexes of tobacco plants,the content of Cd in tobacco plants and soil were determined aimed at providing a reasonable cadmium remediation method for Cd contaminated soil,and achieve the goal of reducing the cadmium content in tobacco leaves and improving the safety of tobacco leaf.The main results as follows:(1)The absorption of tobacco to cadmium was related to the concentration of cadmium in the soil.With the increase of the content of cadmium content in soil,the content of Cd in tobacco roots,stems and leaves increased.The content of Cd in tobacco leaves was the highest,and the roots was the lowest.The content of Cd in different parts of tobacco leaves as follows: upper leaves > middle leaves > lower leaves.When the concentration of Cd in soil was 30mg/kg,the increase degree of the content of cadmium in each part of the tobacco plant was the largest.The enrichment coefficient of cadmium in tobacco ranged from 0.52 to 1.70,and the transfer coefficient of cadmium ranged from 2.20 to 14.45.Under the stress of cadmium,the plant height,leaves number,and the other agronomic indexes of tobacco plant decreased,the biomass of each part of tobacco plant decreased,and the biomass of tobacco leaf decline the most.(2)With the increase of concentration of Cd in soil,the content of P,Ca,Mg,Cu,Mn and Zn in tobacco leaves decreased gradually;the content of K and B increased first and then decreased.With the promotion of the growing period,the content of K in tobacco leaves decreased gradually,the content of Ca,Mg,Mn,Fe and Zn first decreased and then tended to stable,the content of B performed the trend of decrease-increase.During the growth period,some mineral elements were affected by Cd stress,but the effect was not significant.Compared with the control,the correlation between mineral elements in tobacco leaves gradually decreased with the increase of the concentration of Cd in soil.(3)Compared with the treatment without biochar,after the addition of biochar to the two kinds of fertilization method,the root activity of tobacco plants increased by 3.4% and 5.2% respectively;the content of membrane lipid peroxidation product MDA decreased by 29.13% and 16.29% respectively;the activity of antioxidant defense enzymes SOD,POD and CAT increased in tobacco leaves;the biomass of tobacco leaves significantly increased by 67.6% and 24.4.(4)After the addition of biochar to the two kinds of fertilization method,the content of Cd in each part of tobacco plants significantly decreased,the content of Cd in stems and leaves declined the most;the decreasing amplitude of the content of cadmium in different parts of tobacco leaves as follows: upper leaves < middle leaves < lower leaves.The content of Cd in soil and tobacco leaves declined significantly with the combination of biochar with the application of organic fertilizer and compound fertilizer.In addition,the soil p H value and the content of available cadmium in soil performed significantly negative correlation,the content of Cd in tobacco leaves and the available cadmium in soil performed significantly positive correlation.After the Application of biochar to field,the content of heavy metal in tobacco leaves decreased;the physical properties of tobacco leaves performed good;the chemical compositions of tobacco leaves tended to be harmonious;the neutral aroma components of tobacco leaves improved.The quality of tobacco leaf was improved in a certain extent by adding biochar.