Analysis Of Effect And Mechanism Of Inhibiting Cd Accumulation In Soybean Sprouts By Utilizing Siliceous Foliar Barrier Agent

A hydroponic experiment of soybean sprouts under Cd stress was conducted to optimize the formulation and preparation conditions of siliceous foliar barrier agent,so as to prepare a siliceous foliar barrier agent which can efficiently inhibit the Cd absorption of soybean sprouts and provide a new idea for solving the increasingly serious problem of heavy metal pollution of crops.On this basis,through the determination of the root length,plant height,chlorophyll content,Cd content in different parts,chemical forms of Cd and the analysis of FTIR,the inhibitory effect and mechanism of siliceous foliar barrier agent on Cd accumulation of soybean sprouts were explored.In practical application,the Box-Behnken experimental design was used to optimize the spraying mode of the siliceous foliar barrier agent.Following main conclusions were obtained:(1)The best formulation of siliceous barrier agent is 30%sodium silicate,20%humic acid and 10%tannic acid.The best preparation method is agitation at 50 ℃,stirring time for 10 minutes,spraying after 50 times dilution,which can effectively inhibit the absorption of Cd of soybean sprouts.(2)The best spraying length of time is 15 s.The best spraying interval is one day.The best spraying frequency is 3 times every day.(3)Through the analysis of root length and plant height of soybean sprouts,compared with the control group,the root length increase,and the plant height increase significantly by spraying siliceous foliar barrier agent,indicating that siliceous foliar barrier agent can promote the growth of soybean sprouts.(4)Through the analysis of the chlorophyll content of soybean sprouts,compared with the control group,the chlorophyll a/b ratio increase by spraying siliceous foliar barrier agent,which indicated that the photosynthetic activity of soybean sprouts is enhanced by spraying siliceous foliar barrier agent.(5)Through the analysis of the Cd content of soybean sprouts,the siliceous foliar barrier agent can reduce the Cd content in root,stem,cotyledon and leaf evidently,inhibit absorption to Cd in inoculum,especially to accumulation in roots and stems.The transfer coefficient of Cd reduced by spraying siliceous foliar barrier agent,indicating that the transfer ability of Cd from root to stem and leaves is weakened,thus the toxic action to soybean sprouts is alleviated.(6)Through the analysis of the Cd distribution of chemical forms of soybean sprouts,compared with the control group,total Cd content in stems and leaves decrease,and the sum of the proportion of "active state" Cd decrease,while"inert state" Cd increase by spraying siliceous foliar barrier agent,which can reduce the toxic effects of Cd on soybean sprouts.(7)From the analysis of FTIR,it is found that compared with the control group,the siliceous foliar barrier agent can improve the contents of carbohydrate and protein in soybean sprouts,and make the transformation of some ester substances into other substances to improve Cd resistance of soybean sprouts.