Study On The Ecological Adaptability And Cold Resistance Of Tree Peony In Northeast China

Tree peony (Paeonia Sect. Moutan DC) is Chinese traditional flower, and it originates from China, as " The king of flowers ", and connotes the meanings of "prosperity and happiness" and other cultural meanings. After more than 1,000 years of development, the application of natural cultivated area of Chinese tree peony is constantly expanding and also shows good prospect in the Northeast China. However, because of cold weather conditions in Northeast China, it still lacks of the research on introduction, cultivation and breeding of tree peony, so that the development of the regional tree peony can not break through a technical bottleneck. For this purpose, this research is based on the natural ecological conditions in Northeast China, carrying out a systematic investigation to the existing tree peony cultivars resources in Northeast region, studying the physiological and ecological characteristics of tree peony, putting forward the cold resistance evaluation index about tree peony, and conducting a comparative analysis on different cultivar groups about the ecological adaptability and cold resistance, providing an important reference for the introduction, cultivation and development of the tree peony. The main contents include:1. From September 2007 to March 2011, thus study took the combination of field survey and historical textural, and conducted a survey and research on the introduction and the ecological adaptability of the tree peony in the Northeast China region. Then, this study found that:1) The introduction of Northeast China tree peony is distributed below latitude 47 degrees north, a total of about 200 cultivars and types,27,000 plants; 2) Increasing with the latitude, growth and development of Northeast China tree peony phenology period progressively delay (the phenology of growth and development of tree peony would progressively delaied), and foliage senescence, dormancy gradually advanced. The higher the latitude is, the shorter the time of physiological activity is, the number of flowers gradually reduces, floral type degradation/degenerates, mainly with simple flower and few petals of flower. Lignified branches are gradually shorten, the number of buds reduces. Little has changed on leaf morphological index; 3) Significant differences between the cultivar groups, and the flare mudan have relatively good adaptability. The existed introducing can naturally expose overwintering and flower in northernmost region (Daqing); traditional cultivars of tree peony need artificial protection to overwinter to the north of Changchun, most cultivars often suffer from seriously frozen injury.2. Test point is located in Changchun Mudan Garden. This study chooses 13 cultivars to determine the leaf morphological index and photosynthetic features. The results show that:the leaf mass, among the tree peony cultivars, varieties of inter-group difference is significant, the traditional varieties of peony leaves are large and thick, higher specific leaf weight; flare mudan leaves are thin, lower specific leaf weight, but high chlorophyll content. Net photosynthetic rate (Pn) varieties are different, but the variety of inter-group difference is not significant; diurnal variation shows a small number of varieties of photosynthesis "midday depression", the majority of species as a single peak curve; stomatal conductance (Gs), intercellular carbon dioxide concentration (Ci), and transpiration rate (Tr) on the result of changes are consistent with changes in photosynthesis; water use efficiency between species groups (WUE) are significantly different. Flare mudan has higher utilization efficiency of water. It show good adaptability of drought resistance.3. In the winter period, test points is located in Changchun Mudan Garden. The author selects 12 cultivars of tree peony for the test materials, carries out tree peony natural winter observation, measurement under low temperature stress branches and semi-lethal temperature conductivity (LT50) calculation. The polysaccharide content of proline is measured to determine the branch transpiration and growth recovery observed test. The results show that:In the natural winter conditions, the branches of traditional cultivars of tree peony on the ground are all dead, and only a few of cultivars grow from the ground under the branches and flowers, and flare peony survival rate of most cultivars is 60% or more branches, and can flower 3 or above normal. Relative conductivity under low temperature stresses on fitting Logistic equation, goodness of fit R2 above 0.90. LT50 changes with the outside temperature. During the winter LT50 of the cultivars of flare mudan has been lower than traditional cultivars, and the difference is significant. Tissue damage estimates range equation parameters, and shows that there is great potential for cold resistance of tree peony. Freezing peony recovers the growth and it consistents with the estimated LT50. For the first time i have got the dynamic changes of water content of tree peony branches in winter, knowing the changes of water of tree peony branches loss rate in winter. Preliminary interpretation of " Shoot drying" phenomenon is caused by the low-temperature branch tissue damage, leading to water loss, which is resulted into dead branches, not the branches themselves during winter transpiration caused by the " air-dried ". During the winter determined proline content and soluble polysaccharide content in shoots, leaf growth stage determines the membrane permeability, and can be used as reference for the evaluation tree peony cold resistance. It is a complex system that cold resistance capacity of the tree peony is expressed by their genetic characteristics and the combined effects of environmental factors. During the coldest month of winter, branches semi-lethal temperature for the determination of indicators determine the cold resistance of peony more reliable. Selected branches of the lethal temperature measured as an index to evaluate the cold resistance of tree peony is more reliable.In summary, this study shows that extreme low temperature is the dominant factor on ecological adaptation of tree peony introduction to Northeast China. As latitude increases, effective temperature in need decreases, branches lignification become lower, flowering quality and quantity decline. Protection measures should be assisted by artificial cultivation. The photosynthetic characteristics of light energy utilization efficiency can reflect the accumulation of photosynthetic products and the impact on the tree peony growth and development; during the overwinter period, the author uses branches to measure the conductivity and fits the Logistic equation, then estimates LT50, and this method is reliable and feasible to evaluate cold resistance. There are the differences of the ecological adaptability and cold resistance in tree peony cultivars (group); flare mudan should be the main cultivars popularized and applied in Northeast China.