Physiological Responses To Cadmium And High-temperature Stress Of Hygroryza Aristata

Hygroryza aristata was studied to expore its physiological responses to cadmium(Cd)and high-temperature stress in this paper,which provides a theoretical basis for the further protection and utilization.Using hydroponic test at room temporature(25?),2,4 and 6 mg·L-1(T1,T2 and T3)3 concentrations of Cd stress treatment was set,without adding Cd as control(CK),when treated for 0,4,8 and 12 days,leaf morphology was observed,and plant height,roots,relative water content,chlorophyll content,photosynthetic parameters,hydrogen peroxide(H2O2)content,malondialdehyde(MDA)content,proline(Pro)content,antioxidant enzyme[superoxide dismutase(SOD),peroxidase(POD),catalase(CAT)and ascorbate peroxidase(APX)]activities and antioxidant[glutathione(GSH)and ascorbic acid(ASA)]contents were determined respectively.After 12 days of Cd stress,treated under high-temperature(38?)stress for 1 day,and the corresponding physiological and biochemical indicators were determined.Below were preliminary results:(1)Under Cd stress,the growth and development of Hygroryza aristata were inhibited.Morphologically,the leaves of Hygroryza aristata were wilting,dry,chlorotic and yellow,and necrotic spots appeared in severe cases.The plant height gradually decreased with the increase of Cd stress concentration.The total length of roots and the total number of root tips decreased significantly.Physiologically,The chlorophyll content of the leaves was significantly reduced;The photosynthesis was inhibited and the net photosynthetic rate(Pn)was significantly reduced.(2)Cd had serious toxic effects on the leaves of Hygroryza aristata.the contents of H2O2 and MDA in the leaves of Hygroryza aristata increased gradually with the increase of Cd stress concentration.After 4 or 8 days of Cd stress,the content of Pro gradually increased with the increase of Cd stress concentration.After 12 days of Cd stress,Pro content of T1 was significantly higher than those in control,and there's no obvious difference between T2 and control,while Pro content of T3 was significantly lower than those in control.(3)Under Cd stress,antioxidant enzyme activities in the leaves of Hygroryza aristata.The activities of SOD,POD and CAT in the leaves of Hygroryza aristata gradually increased with the increase of Cd stress concentration,and the activity of APX increased significantly as well.The content of GSH increased first and then decreased with the prolongation of treatment time,while the content of ASA decreased significantly.(4)Hygroryza aristata has strong resistance to high temperature.Under high-temperature stress,the content of MDA in the leaves of Hygroryza aristata didn't change significantly,while the content of Pro increased significantly.The activities of SOD,CAT and APX increased significantly,while the activity of POD didn't change significantly.The contents of GSH and ASA decreased significantly.(5)Compared to single Cd stress,the combined stress of Cd and high temperature is more toxic to Hygroryza aristata,and the ability to resist stress is reduced.Compared to single Cd stress,under the combined stress of Cd and high temperature,the contents of MDA and Pro in the the leaves of Hygroryza aristata increased significantly.The activities of SOD and CAT decreased significantly,the activity of POD didn't change significantly,and the activity of APX increased significantly.The content of GSH didn't change significantly and the content of ASA decreased significantly.