Effects Of Exogenous Selenium On Root Morphology And Nutrient Absorption Of Maize And Its Role In Salt Stress

In this thesis,maize(Zhengdan 958,Zea mays L.cv.ZD958)was used as the research material,the effects of two different forms of selenium?Se(?)?Se(?)?on root morphology and nutrient uptake of maize seedlings were studied by nutrient solution culture and soil culture methods,which provided scientific basis for rational selenium supplementation of selenium-deficient soils and remediation of soil selenium pollution in maize planting areas.On this basis,the effects of selenium on biomass accumulation,root morphology,osmotic regulation and antioxidant activity of maize under NaCl stress were studied with sodium selenite?Se(?)?as exogenous selenium,which provided theoretical basis for improving salt resistance of maize.1.Under soil culture conditions,the biomass,total root length,root surface area,nitrogen,phosphorus and potassium accumulation of maize treated with Se(VI)and Se(IV)(10 mg/kg<selenium content<40 mg/kg)decreased with the increase of selenium content,while the average root diameter,selenium content and selenium accumulation increased with the increase of selenium content.At the same selenium content,when the selenium content was less than 5 mg/kg,the biomass of maize treated with Se(VI)was higher than that treated with Se(IV),when the selenium content was more than 5 mg/kg,the biomass of maize treated with Se(IV)was significantly higher than that treated with Se(VI).The accumulation of nitrogen,phosphorus and potassium in maize treated with Se(VI)was significantly higher than that treated with Se(IV)(P<0.05)when the content of Se was less than 10 mg/kg,and the accumulation of nitrogen,phosphorus and potassium in maize treated with Se(IV)was significantly higher than that in Se(VI)treatment(P<0.05).The results showed that exogenous Se(VI)and Se(IV)had inhibitory effects on maize growth.The toxicity of Se(VI)with low content(less than 5 mg/kg of Se)was lower than that of Se(IV),while that of Se(VI)with high content(10 mg/kg<40 mg/kg of Se)was higher than that of Se(IV).2.In the nutrient solution culture,the dry weight of the aboveground part of Se(VI)treated maize was significantly higher than that of Se(IV)treatment;the low concentration of selenium treated(Se(VI)?12.5?M,Se(IV)?25?M)selenium in maize seedlings The content increases with the increase of selenium concentration.The same selenium concentration,when the concentration of selenium was<12.5?M,the accumulation of Se(VI)in the aboveground part of corn was lower than that of Se(IV),when the concentration of selenium was?12.5?M,the accumulation of Se(VI)in the aboveground part of corn is significantly higher than that of Se(IV).Under the same selenium concentration,the accumulation of nitrogen,phosphorus and potassium in Se(VI)-treated maize seedlings was significantly higher than that in Se(IV)treatment.Low concentration of selenium(Se(IV)?6.25?M,Se(VI)?12.5?M)can promote the growth and nutrient uptake of maize,which is characterized by root length elongation,root thickening and the accumulation of nitrogen,phosphorus and potassium.High concentrations of selenium treatment(>12.5?M)resulted in inhibition of corn growth and reduced nitrogen,phosphorus and potassium uptake.3.Based on the experimental study of different selenium forms,the results of adding exogenous selenium and NaCl in the nutrient solution showed that the biomass and total root length,root surface area and root volume of NaCl treatment decreased significantly compared with CK,the three treatments were significantly increased compared to NaCl treatment.The proline content of maize leaves treated with NaCl was significantly higher than that of the control group;the proline content of corn leaves treated with 6.25?M was higher than that of NaCl treatment;the proline content of maize leaves treated with 12.5?M and 25?M was lower than that of NaCl treatment and significantly higher than CK.The contents of K~+and Na~+in corn leaves treated with NaCl increased significantly compared with CK(P<0.05);the content of K~+and Na~+in the aboveground part of corn treated with selenium was lower than that of NaCl treatment,and it decreased with the increase of selenium concentration,and was higher than CK.The superoxide anion content of corn leaves treated with NaCl was significantly higher than that of CK.Compared with NaCl treatment,the content of superoxide anion in corn leaves treated with selenium decreased significantly,and decreased with the increase of selenium concentration.Under salt stress,selenium application can alleviate the damage of salt stress on corn.This is manifested by a significant increase in maize biomass,root elongation and thickening,accumulation of soluble sugar content,and reduction in superoxide anion content.Therefore,it is indicated that selenium in a certain concentration range from 6.25?M to 25?M has better harm to corn seedlings and has a significant effect on improving salt tolerance.