A Comparative Study Of Kentucky Bluegrass And Tall Fescue Seedling Growth And Heavy Metal Accumulation Characteristics Under Cd And Pb Stress

Cd,Pb was the main heavy metal pollutants in the soil, but not the necessary elements for plant growth and development. Cd,Pb accumulation to a certain amount in plants would affect the normal metabolism of material and energy,resulting in plant growth and development was blocked.Kentucky bluegrass(Poa pratensis L.) and tall fescue(Festuca arundinacea L.) were two kinds of widely planted perennial cool-season grasses,trampling resistance,good reproducibility, wide adaptability,strong resistance,available in urban greening,sports grounds and golf course lawn planting.In this study,kentucky bluegrass and tall fescue for the materials,a potted method was used to study the effect of soil Cd,Pb stress on kentucky bluegrass and tall fescue seedling growth characteristics,physiological and biochemical characteristics and heavy metal accumulation characteristics.Explored Cd,Pb toxicological effects on turfgrass and the removing effect of turfgrass to soil cadmium and plumbum.In order to provide a theoretical reference for Cd, Pb contaminated soil restoration and resistance to Cd,Pb stress turfgrass cultivar selection. The results were as follows:(1) Under Cd,Pb single stress,lower concentrations of Cd(Cd20,Cd50) and Pb (Pb200,Pb500) treatments promoted kentucky bluegrass and tall fescue seedling plant height,leaf length,leaf width,root length,seedling fresh weight,kentucky bluegrass seedling leaf proline content,the chlorophyll content of high fescue and that of post-processinglO d,30 d of Kentucky bluegrass,Kentucky bluegrass leaf antioxidant enzyme activity, SOD and POD in leaves of tall fescue and CAT activity after 10 d,20 d treatment.The indicators of turfgrass were inhibited by higher concentration Cd (≧100 mg/kg),Pb (≧1000 mg/kg) treatments.Under Cd,Pb single stress,with Cd,Pb concentration increasing,the leaf and root cell membrane permeability,MDA content of turfgrass seedlings and tall fescue leaf proline content showed an upward trend, membrane permeability and MDA content of turfgrass seedlings were significant increased under higher concentrations of Cd (Cd150, Cd200),Pb (Pb1500,Pb2000).(2) Under Cd,Pb combined stress,low concentrations of Cd,Pb (Pb600Cd40) combined treatment made tall fescue seedling leaf length,leaf width,root length and the growth indexes of kentucky bluegrass increase,high concentrations of Cd,Pb(Pb1000Cd60, Pb1000Cd80)processing made lawn grass seedling growth indicators declined.Lower concentrations of Cd,Pb Combined stress displayed a certain synergy on the growth of kentucky bluegrass and tall fescue seedlings while higher concentrations of Cd,Pb stress showed antagonism.Under Cd、Pb combined stress, leaf and root cell membrane permeability of turf grass seedlings,MDA and proline content of tall fescue showed an increasing trend,the chlorophyll content and antioxidant enzyme activity in the leaves of grass and leaf proline content of bluegrass first increased and then decreased Low concentrations of Cd,Pb (Pb600 Cd40) combined treatment showed antagonism on MDA content in leaves of bluegrass,while high concentrations of Cd,Pb (Pb1000 Cd80)showed a synergistic effect.Lower concentrations of Pb-Cd (Pb600 Cd40) composite stress had a synergistic effect on SOD,POD activity of turfgrass seedlingsin lawn leaves and post-processing 20 d,30 d CAT activity and proline content of bluegrass,high concentrations of Pb-Cd (Pb1000 Cd80) combined stress showed antagonism.(3) With the extension of Cd,Pb single and combined stress time,turfgrass seedlings height, leaf length,leaf width,root length,seedling fresh weight,cell membrane permeability,MDA and proline content showed an increasing trend,namely the highest 30 d,20 d followed,10 d minimum; SOD,POD and CAT activity of turfgrass seedlings and chlorophyll content in leaves of tall fescue first increased and then decreased,20 d is the highest,10 d followed,30 d lowest.Overall, the plant height,leaf length,fresh shoot weight,SOD,POD and CAT activity of tall fescue seedlings were higher than kentucky bluegrass.(4) Under Cd,Pb single and combined stress,Cd,Pb content in leaves and roots of kentucky bluegrass and tall fescue seedlings were higher than the corresponding control,Pb content in the turfgrass body was higher than Cd conten,Cd and Pb content in grass roots was higher than leaves.Under Cd,Pb combined stress,Pb promoted the absorption of Cd,Cd inhibited the absorption of Pb in turfgrass,Cd and Pb levels showed synergistic effect on Cd content of tall fescue seedling roots,while displayed antagonism on Pb content in kentucky bluegrass seedlings leaves and tall fescue seedling roots.