Effects Of Manganese Stress On Antioxidant System And Nitrogen Of The Seedlings Of Different Varieties Maize

Taking five kinds of maize genotypes by regulating manganese concentration and manganese salt type as research object,analyzed effects of manganese stress on different varieties of maize seedlings growth condition,manganese stress and nitrogen content.The results showed that the resistance of five maize varieties,the absorption and toxicity of maize to two kinds of manganese were studied.In this experiment,five maize genotypes were Kenji 1(K),Shuangyu 201(S),Dongqing 1(D),Ji Nongda 516(J)and Xianyu 335(X).Set five manganese concentration gradient respectively:(Mn1),0.005 mmol/L(CK),5 mmol/L(Mn2),10 mmol/L(Mn3),20 mmol/L(Mn4).Two kinds of form: MnCl2.4H2 O and EDTA-Mn.The main results are as follows:Compared with the CK,both forms of manganese stress inhibited the plant height,root length and biomass of the five maize species.Compared with 0.005mmol/L(CK),height of maize treated with EDTA-Mn decreased by 3.7%-53% and treated with MnCl2·4H2O decreased by 5.2%-36.5%.The root length of maize treated with EDTA-Mn decreased by 3.5%-52% and treated with MnCl2·4H2O decreased by 0.2%-34.0%.The shoot biomass was more inhibited by manganese stress than root biomass.With the increase of manganese stress,the root shoot ratio increased gradually,J and D were changed small.S was more affected by stress and had a greater degree of change.Manganese stress increased the activity of SOD,POD and CAT and the content of MDA of five maize seedlings.But SOD,POD and CAT activities have a certain threshold,exceed the tolerance then declined.The SOD,POD and CAT activity of D continued to increase with the increase of manganese concentration,while other varieties decreased.The MDA content of D increased little with the increase of manganese concentration,and the content was the lowest among varieties.S was the largest increase in manganese concentration.The mazes of D have strong resistance,S is weak.The activity of SOD and POD treated with MnCl2·4H2O was higher than that of EDTA-Mn,while the activity of CAT fractions were lower than EDTA-Mn treatment,and the content of MDA in membrane lipid peroxidation was higher than that of EDTA-Mn.Manganese stress inhibited nitrate uptake.With the increasing of manganese concentration,the content of nitrate nitrogen in root decreased,except for J,but the difference was not significant.D decreased the smallest.The content of ammonium nitrogen in K and S increased first and then decreased with the increasing of manganese concentration.The contents of ammonium nitrogen in J and D decreased with the increasing of Mn stress.MnCl2·4H2O treatment of maize seedling root ammonium accumulation was greater than EDTA-Mn treatment.Manganese stress significantly inhibited the synthesis of soluble protein.With the increasing of manganese concentration,the content of solubleprotein in roots decreased gradually.Mn Cl2·4H2O treatment of root soluble protein decreased more than EDTA-Mn treatment.The soluble protein content of root in J was the highest among the five cultivars.Manganese stress affects the efficient distribution of nitrogen nutrients in the roots,hindering the transport of phloem and the accumulation of some nitrogen roots.The degree of inhibition of MnCl2·4H2O treatment was greater than EDTA-Mn treatment.Different concentrations of manganese applied maize significantly increased the manganese content in the shoots and roots of maize seedlings.The uptake of MnCl2·4H2O in the shoot and root of five maize genotypes were higher than that of EDTA-Mn.And the manganese content in the roots were higher than that in the shoot.J and D had lower manganese content.