Study On Cold Hardiness Of Several Magnolia Evergreen Young Seedlings And Their Photosynthetic Characters In Winter And Spring

With the development of social economy and pepole's lives, the gardening of cities had prospered lushly, which provided expansive arena for the use of gardening species. Because of the limination in geology and climate, the northern cities were most composed by hardwood which leaded the stagnancy of winter scenery and the lack of good ecological environment. By the warming of temperature in the world, the diversities of small climate in city also provided the good location for evergreen species. That was to say, we should attach much importance to the appliance of evergreen species in the northern cities.Other wise, because of the total environmental genes's limination, there were many factors influence the safy of species, the key factors were low temperature in winter and high temperature in summer. For the moment, there were few researches about the chilling physiologic and photosynthetic characteristics of evergreen species in winter and spring in the northern-tropical area. This article studied the photo-ecological and chlorofluorescence characteristics in winter and spring of several evergreen species. The results showed:1 The performance and the physiological variation of evergreen species in winter(1) The magnolia species that distributed naturally in northern-subtropical areas had much lower TL50 than that distributed naturally in sourthern-subtropical areas. The chilling resistance abilities of six magnolia species were : Parakmeria lotungensis> Michelia Platypetala > Michelia foveolata > Manglietia insignis > Michelia macclurei > Tsoongiodendron odorurn. (2)All species' contents of MDA ascended during the course of winter and descended at the end of winter. All species' activities of SOD ascended during the course of winter thus to protect the cell, while the activities of POD descended all the time which manifested that it suffered strong breakage in winter.(3) All species' contents of Chl a descended during the course of winter while Chl b varied complicated, three magnolia species that distributed naturally in northern-subtropical areas had much more Car than the other three species during the course of winter, that was probably a good way to protect the cell from cold menace in winter.2 The photo-ecological characteristics of evergreen species in winter and spring(1) The five species' diurnal variation tapes of Pn and WUE in winter were different...