Allelopathy Of Sagittaria Graminea On Plankton

As a new type of aquatic plant,Sagittaria graminea has a wide application prospect in landscape planning in northern China.In this study,phytoplankton sensitive to S.graminea was screened through transplantation and sample plot investigation.The sensitive species Chlorella vulgaris and Tetrahymena cells were used as experimental materials.The cell growth density,chlorophyll a content and antioxidant capacity of S.graminea roots were determined by single cell counting,enzyme-linked immunosorbent assay and the method such as thiobarbituric acid,and explore the effect of secretion on sensitive species in aquatic environment.The main conclusions of this study are as follows:1.The survival rate of S.graminea after transplantation was high was the same as that in the field,but its biological characteristics have changed to some extent.The growth status of plants grown in the field is significantly better than that of transplanted plants,and the indexes of plants cultured in medium are better than those cultured in pure water.The highest germination rate was 65.33% when seeds were soaked in 20% KOH for 8 hours,and the survival rate of young buds was the highest and the seedlings grew well under this condition.The germination and growth indexes in indoor(SN)group were higher than that in outdoor(SW)group.The survival rates of buds in SN and SW groups were 93.3% and 91.7%,respectively.The number of corms was 6.2 and 4.8,and the number of buds was 5.8 and 3.0,respectively.2.The Shannon-Wiener index of the single-dominant community of S.graminea was 0.26 higher than that of the control plot,and there was a significant difference between them.The most sensitive species to S.graminea were identified as C.vulgaris and Tetrahymena.3.High concentration of root exudates of S.graminea reduced the number of C.vulgaris,while medium and low concentration of root exudates of S.graminea had no significant effect on the density of C.vulgaris.With the change of time,all treatments could reduce the content of chlorophyll a of C.vulgaris.High concentration of root exudates of S.graminea had an effect on the content of chlorophyll a of C.vulgaris and the maximum change rate was 21.86%.The SOD activity of C.vulgaris in each concentration treatment was higher than the initial value,while the POD and CAT activity of C.vulgaris in high concentration treatment decreased significantly,but there was no significant difference between low concentration and medium concentration.High concentration of root exudates had the greatest effect on POD and CAT of C.vulgaris,which decreased by 19.79% and 27.27%,while low concentration of root exudates had the greatest effect on SOD of C.vulgaris,which increased by 8.51%.MDA content increased with the increase of root exudates concentration.4.The effect of root exudates of S.graminea on the quantity of Tetrahymena was promoted by low and medium concentrations and was inhibited by high concentrations.High concentration of root exudates of S.graminea had the greatest effect on POD of Tetrahymena,which decreased by 30.60%.High concentration of root exudates of S.graminea had the greatest effect on CAT of Tetrahymena,which increased by 24.07%.High concentration of root exudates of S.graminea had the greatest effect on SOD of Tetrahymena,which increased by 14.46%.The content of MDA in Tetrahymena in the high concentration treatment group was significantly higher than that in the control group.