Screening Of Cadmium Physiological Barrier Agent For Lettuce (Var.ramosa Hort.) And Preparation Of Its Compound Regulators

Cadmium(Cd)is a kind of toxic heavy metal that seriously endangers human health.it can enter the plant through the soil and then enrich it in the human body through the food chain.As a large grain country,it is urgent for China to reduce the content of Cd in soil and alleviate the pollution of Cd in crops.This experiment mainly aims at the screening of lettuce Cd physiological barrier agent and the development of the barrier agent.Through greenhouse pot experiment and field experiment,the barrier agent with the best effect and the best concentration combination are screened out.And try to find the best spraying method which is suitable for the actual production practice.The results are as follows:1.Through greenhouse pot experiment,three concentrations of brassinolactone(EBR)were sprayed on lettuce leaves with 10-11,10-9,10-7mol/L.The experimental results showed that different concentrations of EBR could increase the biomass of lettuce under the stress of Cd.Finally,it was found that spraying 10-11 mol/L EBR had the best effect of reducing Cd,and the content of Cd in lettuce overground was reduced by 32.3%.2.Two combinations of GA3+HA,GA3+Ca(NO3)2 reagents were sprayed on lettuce leaves in greenhouse pot experiment.Design Orthogonal test,The optimum concentration ratios of GA3(3μmol/L)+HA(0.5g/L)and GA3(1μmol/L)-Ca(NO3)2(5g/L)were selected by the determination of biomass,chlorophyll content and Cd element content in lettuce plants.3.Through field experiment,it was verified that the optimum concentration ratio of GA3+HA,GA3+Ca(NO3)2 was screened out in greenhouse,which had the same effect in actual field production.According to the determination of Cd element content in lettuce plants,the Cd content was reduced by 23.3%and 19.2%.4.Five spraying schemes of GA3(3μmol/L)+HA(0.5g/L)and GA3(1μmol/L)+Ca(NO3)2(5g/L)were designed by field experiment.Finally,according to the determination of chlorophy ll content and Cd elements in lettuce plants,we found the best spraying technology which matched with them and was suitable for field production in the century.That is,when lettuce grows to trilobal,the treatment of GA3+HA combination is that GA3(3μmol/L)can be sprayed on the first day(3μmol/L),and HA(HA:3g/L)on the second day.The combination of GA3+Ca(NO3)2 was sprayed with GA3(1μmol/L),on the first day and Ca(NO3)2(15g/L)on the second day,and then treated again in the second week and the first week.the content of Cd could be reduced by 29.2%by the two combination reagents combined with the best spraying technique,respectively.25.6%.In conclusion,EBR was selected as Cd physiological barrier agent,and the optimum concentration of 10-11mol/L was selected.At the same time,the previous work of the laboratory was optimized,and the optimum concentration ratio of GA3+HA,GA3+Ca(NO3)2 was found.Through the field experiment,the spraying technology,which matches the two kinds of combination reagents and can be applied to the actual production practice,is found out.