Effects Of Exogenous Salicy Acid On Growth And Physiology Of Zoysia Japonica Under Drought Stress

With the rapid development of modern economy, city Greenbelt has become akey of city construction. The water shortage has also become one of the importantenvironmental issue,facing the water tension for life,the problem of city Greenlandirrigation wanter becomes an important factor restricting the development of urbangreen space. Zoysia the trampling resistance, high temperature, drought and othercharacteristics, is ideal for the construction of a modern city lawn grass and Zoysiahas been widely used in a variety of turf establishment, particularly in arid andsemi-arid regions. Studies have shown that drought stress can restrict plant growth oreven damage to the physiological function; Zoysia under water stress, biomass, plantheight and leaf length will be limited to protect the activity decreased, while theaccumulation ofa large number of osmotic adjustment substances, water stress willalso the Zoysia limit photosynthesis and reduce biomassStudies have shown that drought stress can make plant growth be restrictedoreven damaged.Under the certain water stress,the biomass,plant height and leaf lengthof Zoysia were restricted,protection enzyme activity decreased,while a large numberof osmothic adjustment substances accumulated;water stress can also restrict thephotosynthesis of Zoysia japonica.When the plants are in severe shortage of waterenvironment,plant growth can be obviously restricted,even can lead to plant death.Innowadays, researches on using adversity of exogenous had a lot;Salicylic acid as asmall molecule phenolic compounds has been widely used in the study of plantdisease resistance and stress resistance in the last century,and has obvious effect ofrelieving to plant.In this experiment, Zoysia japonica is taken as experimental materials, studiedthe effects of different concentrations of salicylic acid on Zoysia growth underdrought stress indicators.The experiments were divided into four groups, contrast andtreated with salicylic acid, the concentration of salicylic acid is set up threeconcentration gradient:0.1mmol/L,0.5mmol/L and1.0mmol/L, exogenous substances are taken leaf spraying method, the contrast spray isometric distilledwater.By weighing weight controls water ratio of experimental material.Bycomparing changes of the different treatment of Zoysia growth index,enzymeactivity,photosynthetic indexes as well as chlorophyll fluorescence parameters,studying influence of exogenous salicylic acid pretreatment on zoysia grasses underdrought stress.Through research and analysis, exogenous salicylic acid has positive influenceon drought stress Zoysia.Under drought stress,exogenous salicylic acid treatment cansignificantly improve the Zoysia grass superoxide dismutase （SOD）, peroxidase（POD）, catalase （CAT） activities,decrese membrane peroxidation productmalondialdehyde （MDA） content and the osmotic adjustment of proline （Pro） content,through improving the endogenous protection system, alleviates the effect of droughtstress on harm zoysia.0.5mmol/L salicylic acid treatment has more obviouseffects.Studied on effect of exogenous salicylic acid on photosynthetic parameter ofdrought Zoysia. Results show that,0.1mmol/L salicylic acid treatment cansignificantly increase leaf NET photosynthetic rate of zoysia （Pn）, water useefficiency （WUE） and transpiration rate （Tr）, and efficaciously relieve intercellularconcentration of CO₂reduction （Ci）, stomatal conductance （Cond） declined. Salicylicacid treatment can effectively mitigate photosynthetic pigment contents of droughtstress zoysia leaves reduced, reduces zoysia initial fluorescence （Fo）, the coefficientof non-photochemical quenching （qN） increased, meanwhile, the Ray grass ofmaximum fluorescence （Fm）, variable fluorescence （Fv）, original light transformationefficiency （Fv/Fm）, light reaction Center PSII of potential activity （Fv/Fo）, lightreaction Center PSII actual of light chemical quantum efficiency （φ PSII）, tablesightseeing electronic passed efficiency （ETR） and light chemical quenching fightcoefficient （qP） has clear of mitigation role.To sum up, exogenous salicylic acid has certain impact on the growth andphysiological of Zoysia under drought stress.In the growth and enzyme activity ofZoysia, Salicylic acid treatment is significantly higher than the control treatment, but0.5mmol/L salicylic acid treatment is significantly higher than0.1mmol/L and1.0mmol/L treatment, and shows the best mitigation effect;while the impact on the the Zoysia photosynthetic pigment content, photosynthetic indicators and chlorophyllfluorescence parameters, processing performance of the low concentration is moreobvious than others,0.1mmol/L salicylic acid treatment are more sensitive tophotosynthetic fluorescence indicators of drought Zoysia,and demonstrated asignificant mitigation effection.