Physiological Effects Of Exogenous GABA On Festuca Arundinacea Under High Temperature And Drought Stress

Because of the extreme climate of the world,there are high temperature and drought disasters,seriously affecting the production and development of plants in China.Tall fescue(Festuca arundinacea Schreb)is one of the most popular cold season turfgrass in China.It is often subjected to high temperature and drought stress during the process of growth and development,leading to low yield of tall fescue and even large area death.In order to study the high temperature and drought stress on the physiological influence of tall fescue plants,and find the way to effectively enhance the ability of tall fescue plants to resist high temperature and drought.In this experiment,the tall fescue was used as materials and applied ?-aminobutyric acid(?-aminobutyric acid,GABA)at a concentration of 5 mmol / L,sampled on the 7th day,14 th day and 21 st day respectively,exploring the effect of high temperature and drought stress on tall fescue relative conductivity,MDA(Malondialdehyde,MDA)of tall fescue plants content,chlorophyll content,superoxide dismutase(Superoxide dismutase,SOD)activity,catalase(Catalase,CAT)activity,peroxidase(Peroxidase,POD)activity,turf quality(Turf quality,TQ)and the net photosynthetic rate.The main result as below.1.High temperature and drought stress caused the MDA content,the relative conductivity of tall fescue plants increased,and with high temperature and drought stress time increasing,the relative conductivity and MDA content increased.When using exogenous 5mmol/L concentration of GABA high temperature and drought stress of tall fescue plants,with high temperature and drought stress time increasing,tall fescue plants relative conductivity and MDA content decreased significantly compared with the control group.Under the high temperature stress,the relative conductivity and MDA content decreased significantly on the 14 th day compared with the control,respectively decreased by 34.85% and 29.76%.Under drought stress,the relative conductivity decreased significantly on the 21 st day compared with the control group,decreased 16.87%.The content of MDA significantly decreased by 19.6% on the 14 th day,compared with the control group,showed that when the tall fescue plants were under high temperature and drought stress,the cell membrane permeability and membrane lipid peroxidation were increased,and the use of exogenous GABA could effectively alleviate the increase of cell membrane permeability and membrane lipid peroxidation in tall fescure due to the high temperature and drought stress.2.With the increase of high temperature and drought stress,the activity of SOD and POD in tall fescue plants increased first and then decreased.Under high temperature stress,CAT activity in tall fescue plants decreased continuously,downward trend slow down after.Under the drought stress,the activity of CAT in tall fescue plants increased first and then decreased.When using exogenous 5mmol/L concentration of GABA high temperature and drought stress of tall fescue plants,the activities of SOD,POD and CAT in the plants were significantly increased,on the 7th day,SOD activity reached the maximum,respectively 144.56% and 129.12% compared the original.On the 14 th day,POD activity reached the maximum,respectively 123.18% and 130.07% compared the original.Under the high temperature stress,the activity of SOD was the largest on the 14 th day,which was 69.08% higher than that of the control.The difference for the POD activity between test group and the control was the highest on the 14 th day,which was 30.08% higher than that of the control.On the 21 st day,the activity of CAT was the highest compared with the control,which was 66.85% higher.While under drought stress,the activity of CAT and SOD on the 7th day reached the maximum value,131.20% and 129.12% compared the original.On the 14 th day,the activity gap of SOD and CAT was the highest compared with the control,which was 15.39% and 52.27% higher.On the 21 st day,the POD activity was the largest,which was 57.28% higher than the control.The results showed that exogenous GABA could improve the activities of SOD,POD and CAT in tall fescue plants and enhance the ability to remove the reactive oxygen species under high temperature and drought stress.3.With the increase of high temperature and drought stress,the chlorophyll content,turf quality and net photosynthetic rate of tall fescue were decreased.Under high temperature stress,the chlorophyll content decreased rapidly after the first slow,turf quality and net photosynthetic rate was slow after the first downward trend.Under drought stress.turf quality decreased soon after the first slow,chlorophyll content and net photosynthetic rate was soon after the first slow downward trend.When using exogenous 5mmol/L concentration of GABA high temperature and drought stress of tall fescue plants,chlorophyll content,turf quality,net photosynthetic rate decreased significantly compared with the control group.Under the high temperature stress,the net photosynthetic rate was the largest on the 14 th day,which was 38.53% higher than that of the control.On the 21 st day,the chlorophyll content and turf quality were the highest,which was 22.99% and 33.33% higher.The gap between the lawn and the control was the highest on the 14 th day,which was 66.67% higher than that of the control.On the 21 st day,the difference of chlorophyll content and net photosynthetic rate was the highest,which was 17.88% higher and 48.16% respectively.The results showed that chlorophyll content,turfgrass quality and net photosynthetic rate were decreased under high temperature and drought stress,while the use of exogenous GABA could effectively alleviate the reduction in chlorophyll content,turf quality and net photosynthetic rate of tall fescue plants caused by high temperature and drought stress.