Research On The Screening Of Turfgrass For Green Roofs

Roof greening construction can increase the amount of urban green,alleviate the heat island effect,reduce noise and dust at the same time for building insulation and heat preservation,the substrate layer and vegetation layer can also catch rainwater.Roof greening construction methods are different under different regional climate conditions,which are directly affected by load,planting substrate,plant species and other factors.In order to explore the optimal type of roof greening in the semi-humid area of warm temperate zone,the first single grass species analysis experiment selected 6 common turfgrass(Zoysia japonica Steud,Cynodondactylon,Agrostis matsumurae,Poa pratensis,Lolium perenne,Festucaelata Kengex)as materials,and planted them on the roof with garden soil as the substrate through design experiment.By measuring the contents of CHL,MDA,SOD,CAT and POD of six common turfgrass,the stress resistance strength of turfgrass was analyzed.It was found that Festucaelata Kengex E,Cynodondactylon and Lolium perenne L was better.Four formula substrates(A peat:perlite:vermiculite:wheat straw=4:3:1:2,B peat:perlite:vermiculite=1:1:1,C garden soil:vermiculite:perlite:humus=2.5:0.5:2:5,D garden soil)and four ratios of turfgrass(A Cynodondactylon:Zoysia japonica Steud:Lolium perenne=7:2:1,B Poa pratensis L:Agrostis matsumurae Hack:Lolium perenne=5:4:1,C Poa pratensis L:Festucaelata Kengex:Lolium perenne=5:3:2,D Zoysia japonica Steud:Cynodondactylon=2:1)were interplanted,and the substrate height was set at three levels:10cm,15cm and 20cm.The MDA,POD,SOD,CAT and CHL of turfgrass were analyzed,and the membership function values were used to sort.The results show that:1.In the experiment of single species of turfgrass,it was found that the three kinds of turfgrass,such as Cynodondactylon,Lolium perenne and Festucaelata Kengex,grew well in the roof environment,with strong adaptability and high resistance to adversity.2.It was found that the combination of turfgrass,substrate ratio and substrate thickness had significant effects on the contents of MDA,POD,CAT,SOD and CHL of turfgrass in the mixed planting of turfgrass and three thickness substrates.(1)The best dust retention effect of Agrostis matsumurae Hack was 2.6g/m~2,and the worst dust retention effect of Lolium perenne was 0.5g/m~2.(2)There was a positive correlation between substrate thickness and grass biomass in a certain range.In the environment of 15-20cm thick substrate,the amount of lawn green tended to be stable.A Cynodondactylon:Zoysia japonica Steud:Lolium perenne(7:2:1)in the matrix A peat:perlite:vermiculite:straw plant ash(4:3:1:2),BPeat:Perlite:Vermiculite(1:1:1)and C garden soil:vermiculite:perlite:humus(2.5:0.5:2:5)remained stable and high,and the maximum biomass reached 7.5g/m~2.(3)Turfgrass coverage increased with substrate thickness,and finally stabilized gradually.The maximum coverage was 93.8%in the 20cm thick matrix A peat:perlite:vermiculite:wheat straw(4:3:1:2)and Cynodondactylon:Zoysia japonica Steud:Lolium perenne(7:2:1).(4)20cm-thick matrix B peat:perlite:vermiculite(1:1:1)can reduce the building roof temperature by 8℃in summer.(5)Matrix C containing perlite and vermiculite(garden soil:vermiculite:perlite:humus=2.5:0.5:2:5)has a minimum bulk density of 0.08g/cm~3.(6)Mixed matrix A(peat:perlite:vermiculite:wheat straw=4:3:1:2)with A thickness of20cm had the best effect of intercepting rainwater,which could reach 107mm.(7)Poa pratensis L:Festucaelata Kengex:Lolium perenne(5:3:2)reached A maximum of291 days in the environment of peat:perlite:vermiculite:wheat straw(4:3:1:2).In the climate environment of Shandong Province,group D(Zoysia japonica Steud:Cynodondactylon=2:1)in the environment of 20cm matrix B peat:perlite:vermiculite(1:1:1)had the best growth state,and the cooling effect of group D was the best.In the 15cm matrix C garden soil:vermiculite:perlite:humus(2.5:0.5:2:5)environment,group C(Poa pratensis:Festucaelata Kengex:Lolium perenne=5:3:2)can also adapt to the roof environment,and carry out normal physiological and biochemical activities.Moreover,the plant density of this combination is the minimum,and the load requirements are lower.Roof greening is an important content in the process of sponge city construction,and the choice of grass seed and planting substrate are the key factors for the smooth implementation of roof greening technology.According to the specific situation and demand,turf grass and substrate should be selected to achieve the best expected effect.It is expected that this study can promote the construction of roof greening and provide impetus and basis for the construction of eco-city.