Studies Of Trampling Resistance On Eight Wild Kentucky Bluegrass In Gansu Province

Kentucky bluegrass(Poa.pratensis L.)has been widely used for turf establishment especially in soccer field,golf course,tennis court,recreation site and some fields which are overused in the region of North,Middle and South(part of the cold regions)China because it has the characteristics of well-developed rhizome,long-green period,long life cycle,strong-cold resistance,strong resistance to trampling and strong adaptability to environment.Currently,it is one of the major cold season turf grass varieties in the establishment of turf.However,very few cultivated varieties were resistant to strong trampling.The stress resistance germplasm resources of Kentucky bluegrass in Gansu Province are very rich and have much promise to be exploited in the future.In present study,eight wild Kentucky bluegrass which were collected from Gansu were taken as materials,meanwhile the commercial variety Midnight Poa pratensis was used as the control.Four treatments,no trampling(contrast)light trampling(trampled once a day),moderate trampling(trampled twice a day)and heavy trampling(trampled three times a day),were applied to artificially imitate the trampled stress.The effects of trampling intensity on the turf-used characteristic,physiological characteristics of Kentucky bluegrass,along with the physical and chemical properties,microbial quantity and enzyme activity of soil were studied to synthetically evaluate the trampling resistance and select the germplasm with strong trampling resistance.The study will provide theoretical basis for screening new breeding of Kentucky bluegrass varieties and for establishment and management of sports turf.The main results were as follows:1.With the increase of trampling intensity,the density,coverage,consistency,color,height,underground and aboveground biomass and the growth rate decreased gradually,the texture optimized,and the root system became shallow.The trampling resistance orders of all the materials were as follows: Poa pratensis(Qingzhou)>Poa pratensis(Qingshui)>Poa pratensis(Kangle)>Poa pratensis(Yuzhong)>Midnight Poa pratensis>Poa pratensis(Xihe)>Poa pratensis(Sunan)>Poa pratensis(Weiyuan)>Poa pratensis(Anding).2.The content of soluble sugar(SS),soluble protein(SP),chlorophyll(Chl)and the activities of catalase(CAT),peroxidase(POD)and superoxide dismutase(SOD)in Kentucky bluegrass' s leaves decreased gradually with the increase of trampling intensity and were all significantly lower than that of control under moderate trampling stress(P<0.05).The relative membrance permeability(RMP),content of free proline(Pro),malondialdehyde(MDA),hydrogen peroxide(H2O2),hydroxyl radical(·OH)and the production rate of superoxide ion(O2-)in Kentucky bluegrass' s leaves increased with the raise of trampling intensity.All the indexes were significantly higher than that of the control under moderate trampling treatment(P<0.05)except for the content of hydrogen peroxide(H2O2).The RMP,the content of MDA,the production rate of superoxide ion(O2-)of the Kentucky bluegrass were extremely significantly negatively correlated with the trampling resistance(P<0.01).There were significant negative correlation between the content of pro and the trampling resistance(P<0.05).The CAT activities,the POD activities,along with the SS and Chl content were highly significantly positively correlated with the trampling resistance(P<0.01).A significant positive correlation presented between the content of SP and the activities of SOD and the trampling resistance(P<0.05).And the order of the relevance was as follows:POD>CAT> MDA>Chl>RMP>SS>O2->SOD>Pro>SP.3.The moisture content,organic content,porosity of soil and field water capacity decreased gradually with the increase of trampling intensity and moisture content was significantly lower than that of control under moderate trampling(P<0.05).The field water capacity was decreased gradually and the capacity of 0 to 5 centimeter was higher than that of 5 to 10 centimeter.The soil bulk density showed an increased trend and became significantly higher than that of control under moderate trampling(P< 0.05).The soil compaction increased gradually and fell firstly and then increased with the increase of soil depth.The soil compaction and the soil bulk density were very significantly negatively correlated with the trampling resistance(P<0.01).The moisture content,organic content of soil were significantly positively correlated with the trampling resistance(P<0.05).And the order of the relevance was as follows: soil compaction>soil bulk density>soil moisture content>soil organic content.4.The quantity of fungi,bacteria and actinomycetes in soil were decreased gradually with the increase of trampling intensity;The quantity of fungi was significantly lower than that of control(P<0.05)under light trampling while that of bacteria and actinomycetes were lower than that of control under moderate trampling(P<0.05).The urease activity,alkaline phosphatase activity,invertase activity and catalase activity in soil were decreased with the increase of the trampling intensity,they were significantly lower than that of controlunder moderate trampling(P<0.05).The quantity of bacteria and the activities of urease were very significantly positively correlated with the trampling resistance(P<0.01).The quantity of fungi and actinomycetes and the activities of catalase were significantly positively correlated with the trampling resistance(P<0.05).And the order of the relevance was as follows:bacteria population>invertase activities>actinomycetes activities>fungi population> catalase activities.