Effects Of Sulfur And Selenium On Physiological Characteristics And Cadmium Accumulation In Broccoli Seedlings Under Cadmium Stress

Using broccoli(Brassica oleracea L.var italica)as the research material of this experiment.The seedlings were grown in nutrient solution with different concentrations of sulfur,selenium,cadmium.The growth,photosynthesis,osmotic adjustment substances,antioxidant regulatory substances,selenium and cadmium contents of broccoli were analyzed and the effects of physiological and biochemical,selenium and cadmium accumulation in broccoli seedlings under different hydroponic conditions were discussed.The aim was to provide some theoretical parameters for the selenium-enriched cultivation of vegetables and the cadmium stress resistance of plants affected by selenium and sulfur.The main results were as follows:1.The plant height,root length,stem diameter and fresh weight of broccoli seedlings were significantly inhibited by cadmium treatment.The root length,stem diameter,fresh weight and root activity increased when the sulfur concentration was increased,which promoted the growth of broccoli seedlings.Under the treatment of sulfur deficiency(0m M)and selenium,the inhibition of seedling growth by cadmium was enhanced;plant height,stem diameter and fresh weight growth under cadmium stress were promoted under 1 m M sulfur and selenium treatment;4 m M sulfur and selenium together promote growth but the effect is weakened.2.The photosynthetic pigments,Pn,Gs,Tr,Fv/Fo,Fv/Fm,and Y(Ⅱ)and q P values of broccoli seedlings decreased significantly under cadmium treatment,and photosynthesis was inhibited.The accumulation of photosynthetic pigments was improved under the treatment of 1 m M sulfur.The stomatal opening and photosynthetic rate were affected by different sulfur and selenium application.The advantages of sulfur and selenium combinations vary depending on the concentration of cadmium treated.3.The content of soluble sugar,Pro and MDA in broccoli seedlings was significantly increased under cadmium stress.The content of soluble protein and Pro in the leaves of broccoli seedlings increased significantly,and the content of MDA decreased when 4 m M sulfur was added under cadmium stress.The content of soluble sugar,soluble protein and MDA was significantly increased due to the combination of sulfur-free(0 m M)and selenium,under cadmium treatment.The content of Pro and soluble sugar was significantly increased,and the content of MDA was decreased but not significantly applied by 1 m M sulfur-selenium treatment under cadmium treatment.The content of Pro in the leaves treated under 100μM cadmium increased,and the soluble sugar and soluble protein content under 10μM cadmium treatment decreased significantly when treated with4 m M sulfur selenium.4.The activities of SOD and POD in broccoli seedlings increased significantly,and the content of As A increased under cadmium stress.The activities of SOD,CAT and POD were significantly improved,and the content of As A in leaves and stems was significantly improved when the trace sulfur and selenium are treated,under cadmium treated.The activity of SOD,CAT and POD and the content of As A in stems and leaves were significantly reduced when treated with 4 m M sulfur selenium under cadmium treated,which was close to the results of S1Se0Cd0 treatment,but the As A content in roots increased significantly.5.With the addition of sulfur-free and selenium,the accumulation of selenium in the stems and leaves of broccoli decreased with the increase of cadmium concentration and increased significantly in the roots simultaneously.The accumulation of selenium in the leaves was significantly promoted when the 1 m M sulfur-selenium was applied under cadmium treatment,which was higher than that of the sulfur-free treatment.The cadmium content in various parts of broccoli increased with the increase of cadmium treatment concentration.The content of selenium and cadmium in broccoli decreased when the sulfur content increased,the absorption and accumulation of selenium in broccoli seedlings were significantly inhibited when treated with 4 m M sulfur under cadmium stress.There was no significant effect in the cadmium content in the roots of broccoli seedlings under the application of sulfur and selenium,but the treatment of 1 m M,4 m M sulfur and selenium increased the cadmium content in leaves.6.The content of acid-soluble SH,GSH and PCs in broccoli seedlings was significantly increased under cadmium treatment.Under cadmium stress(100μM),the application of sulfur increased the content of SH and GSH in roots and leaves and the content of PCs in stems and leaves.The application of sulfur-free and selenium increased the content of SH and PCs in leaves and decreased when 4 m M sulfur and selenium treated.The content of SH in the stem and the GSH content in the leaves increased when 1 or 4m M sulfur with selenium were treated,the result of 1 m M S treatment was more significant.The contents of SH and GSH in broccoli seedlings were mainly in roots under different treatments,and PCs were the most in leaves.