Study Of Cultivation And Adaptability Of Several Introduced Ground Covers

The research was done in nursery of Beijing Forestry University Ltd. and greenhouse of school of Landscape of Beijing Forestry University.The research mainly includes introduction,cultivation and adaptability on ground covers - cultivars of Hemerocallis and Sedum.The research had been carried through for nearly three years.The results were as follows:(1) The three cultivars of Hemerocallis, H1,H2 and H3 sprouted during the last ten days of Mar.in Beijing area. Florescence appeared during the first ten days of Jun.to the middle ten days of Jul..Their started to wilt during the last ten days of Oct.. The height of cultivars in Hemerocallis was 50⁶0cm,and the beautiful flowers were fresh and big.The plants are graceful and plumpy and covering speed is fast.The S1 sprouted during the middle ten days of Mar., and florescence appeared in the first ten days of sep. to the first ten days of Oct.,then stared to wilt during the last ten days of Oct.. The height of S1 was 25³0cm, Florescence was late,and the anthotaxy was white and dense.The whole plant was fleshy and covering speed was fast.(2) The adaptability of tested cultivars to different irradiance and soil fertility levels indicated that Hemerocallis could normally grow and bloom in full sun,50% full sun and 25% full sun.All parameters of growth and ornamental feature didn't show distinct difference in three irradiance and soil fertility levels.S1 could grow and bloom in three irradiance levels,but there was distinct difference between full sun and other irradiance levels on diameter of the plant.shading resulted in falling of plants during of the late.There was not distinct difference in three soil fertility levels.Ivy could normally grow with three irradiance levels,but length of stems was distinctly different between full sun and other irradiance levels.The length of stems of control was shorter than that of fertilization.Based on the results above,manage technique rules on Hemerocallis and sedum were established.(3) The results of physiological and biochemical changes of cultivars of Hemerocallis and Sedum after water stress showed that plants could minish hurt to cells by accelerating senescence of old leaves,keeping high water content in leaves and enhancing activity ofprotected enzymes,etc.In condition of water stress ,three cultivars of Hemerocallis behaved similarly but not the same.The drought resistance of H2 was higher than HI and H3,behaving in slower senescence, higher activity of protected enzymes etc.The drought resistance of H3 was lowest.In condition of water stress in SI,cell membrane leakage gradually increased,activity of protected enzymes and content of metabolizmg substance didn't change distinctly,which indicated the different mechanism of drought resistance from Hemerocallis.(4) The result of WUE of Hemerocallis was H3>H2>H1,indicating that consuming the same amount of water,H3 could fix more CO₂ ,namely higher WUE. The Durnal changes of photosynthesis indicated obvious two-peaks curve.The peak of the sunny day appeared at 10:00 a.m.and 14:00 p.m..(5) Heat tolerance of Hemerocallis, Sedum cultivars and Matteuccia struthiopteris (M)was measured by electrolyte leakage.Sigmoidal response curve existed between the relative injury value occurring in leaf tissue discs and treatment temperature,which accorded with Logistic equation/The LT₅0 was HI 62. 41℃, H2 62. 30℃, H3 61.74℃, M 60.98℃, S1 53. 72℃, respectively according to formula.(6) Synthetizing all characters in ground covers,a quantitive estimating standard was established .The indexes choosed included natural height of plant, production cycle,view value,adapability,etc..Acorrding this creterion,the H1,H2,H3, M and SI got scores of 60,60,60,61,52 respectively,which means all the tested cultivas and spcies were qualitied to be applied to the urban greening..