The Regulation Of Exogenous Salicylic Acid On Physiological Of Alternanthera Philoxeroides Under Perchlorate Stress

In order to explore the regulatory effects of salicylic acid(SA) on the response of aquatic plant under perchlorate stress(ClO4-), a water culture experiment was conducted with the experimental materials of Alternanthera philoxeroides to study the effects of different concentrations of exogenous salicylic acid(0.05,0.1,0.2,0.4mmol/L)on growth and physiological characteristics and ultra-structure under the condition of perchlorate stress. The results showed as follows:(1) The SA treated groups could alleviate the growth inhibition effects of Alternanthera philoxeroides under ClO4- stress. Compared with the ClO4- stress group, the relative growth yield, relative stem length, relative root length, leaf fresh weight, stem fresh weight and root fresh weight of the SA treated groups were increased in different degrees,the observation of appearance shape also showed the regulatory effects of SA. It was considered that the optimal concentration of SA in alleviating perchlorate stress was 0.2mmol/L.(2) Compared with the ClO4- stress group, the SA treated groups alleviated the damage degree of the cell structure of Alternanthera philoxeroides leaves, increased the protective enzyme activities(SOD,POD,CAT), soluble protein content(Pr), proline content(Pro) and chlorophyll relative content, decreased malondialdehyde content(MDA) to some extent. The treatment of 0.2mmol/L of SA was the optimal concentration.(3) Through analyzing the chlorophyll fluorescence parameters of different periods, the chlorophyll fluorescence induction kinetics, ETR-PAR curve and the dark relaxations of non-photochemical quenching, the results showed that SA treatments reduced the change range of chlorophyll fluorescence parameters of Alternanthera philoxeroides, improved the ability of Alternanthera philoxeroides to use of light energy and adapt to high light. The treatment of 0.2 mmol/L of SA was the optimal concentration.(4) Compared with the ClO4- stress group, the SA treated groups alleviated the damage degree of the cell structure of Alternanthera philoxeroides roots, increased the root activity, the protective enzyme activities(SOD,POD,CAT) and the Pr content, decreased the MDA content to some extent, inhibited the ClO4- absorption in root.The treatment of 0.2 mmol/L of SA was the optimal concentration.