Regulatory Effects Of Combined Application Of SA,Proline And GABA On The Antioxidant System Of Rice Under Salt Stress

Salt stress is one of the major abiotic factors limiting plant growth and crop yield.Salicylic acid(SA),proline(Pro)and γ-aminobutyric acid(GABA)play an important role in plant growth and development and response to stress,especially in the quenching of reactive oxygen species.In order to explore whether their combinations had synergistic effect on the antioxidant system of rice under salt stress,the effects of foliar application of single and combination of exogenous SA,Pro and GABA at tillering or booting stage on the antioxidant enzyme system,ASA-GSH cycle in functional leaves and yield of rice under salt stress were studied in this experiment using two contrasting rice cultivar(salt tolerance cultivar Longdao 5 and salt sensitive cultivar Mudanjiang 30).The concentration of SA,Pro and GABA obtained from preliminary trials.The aim of this study was to clarify the effects of exogenous SA,Pro and GABA on the antioxidant system of rice under salt stress,to explore the interaction of three exogenous substances,to enrich the physiological mechanism of salt tolerance in rice,and to provide a theoretical basis for the development of salt-tolerant cultivation measures.The main results of this study are as follows:(1)The activities of SOD,POD,CAT,APX,MDHAR,DHAR,GR in the functional leaves of rice were significantly increased under salt stress,and the contents of ASA,GSH,MDA and H2O2 were significantly increased.Compared with Mudanjiang 30,Longdao5 maintained high activity of SOD,POD,CAT,APX,MDHAR,DHAR,GR and high levels of ASA and GSH content,significantly reduced the content of MDA and H2O2.Single and combination of exogenous SA,Pro and GABA decreased the content of MDA and H2O2 and alleviated the oxidative damage induced by salt stress,and improved the yield of rice under salt stress by increasing the antioxidant system of Longdao5 and Mudanjiang30.(2)The effect of exogenous SA,Pro and GABA on the yield of Mudanjiang was higher than that of Longdao 5 under salt stress,and foliar spraying at tillering stage was better than that of booting stage.The activities of SOD,POD,CAT,APX,MDHAR,DHAR,GR and contents of ASA and GSH improved by exogenous SA,Pro and GABA in Mudanjiang30 were significantly higher than those in Longdao 5 under salt stress.In addition,the effect of spraying exogenous substances at the booting stage on the MDHAR activity of Mudanjiang30 was better than that of Longdao 5.The effect of foliar spraying exogenous SA,Pro and GABA at tillering stage on the activity of POD,MDHAR,GR and contents of ASA and GSH in Longdao5 was higher than that of booting stage.The effect of SA and Pro on the activity of CAT,and the effect of Pro on the activity of SOD in Longdao5 was higher than that of booting stage.The effect of foliar spraying exogenous SA,Pro and GABA at tillering stage on on the activity of SOD,POD,DHAR,GR activity and contents of ASA and GSH in Mudanjiang30 at tillering stage was better than that of booting stage.In addition,the regulation of DHAR activity at the tillering stage of Pro was greater than that at booting stage.(3)The combination effect of exogenous SA,Pro and GABA on the yield of Mudanjiang was higher than that of Longdao 5 under salt stress,and foliar spraying at tillering stage was better than that of booting stage.The activities of SOD,POD,CAT,APX,MDHAR,DHAR,GR and contents of ASA and GSH improved by combination of SA,Pro and GABA in Mudanjiang30 were significantly higher than those in Longdao 5 under salt stress.The effect of foliar spraying combinations of SA,Pro and GABA at tillering stage on the activity of SOD,MDHAR,GR and contents of ASA in Longdao5 was higher than that of booting stage.The effect of foliar spraying combinations of SA,Pro and GABA at tillering stage on on the activity of SOD,GR activity and contents of ASA and GSH in Mudanjiang30 at tillering stage was better than that of booting stage.The effect of SA+Pro and Pro+GABA on the activity of POD,and the effect of SA+GABA,Pro+GABA and SA+Pro+GABA on the activity of DHAR in Mudanjiang30 was higher than that of booting stage.(4)Compared with single-agent treatments of SA,Pro and GABA,combination of SA and Pro /GABA showed synergistic effect on salt yield and antioxidant system under salt stress.Joint application of Pro and GABA synergistically enhanced the yield of rice under salt stress,increased the activity of SOD,MDHAR,DHAR and GR,as well as the contents of ASA and GSH,decreased MDA and H2O2 contents,but did not show cumulative effect on the activities of POD,CAT and APX.Combination of SA,Pro and GABA showed synergistic effect on the rice yield and antioxidant system under salt stress.From the effect of exogenous substances on rice yield control under salt stress,SA+Pro+GABA>SA+GABA>SA+Pro >Pro+GABA...