| Syringa pinnatifoliais a member of Genus Syringa,Family Oleaceae,which is an unique endangered species at protection categories 3 in China,the only pinnately compound plant of Syringa.It is a beautiful plant because of the luxuriant foliage and various flowers whose color is diversiform and fragrance is intoxicated,which proves that it has high ornamental value.It also has high medicinal value because its shoots and roots can be commonly used as rare medicinal materials in Mongolian medicine.But S.pinnatifolia is still living in the wild at present,the distribution range of its population is gradually shrinking.Therefore,the study of the mechanism of seed dormancy and germination characteristics can reveal the cause of the weak sex under natural conditions,provide theoretical basis for breeding technology research of S.pinnatifolia,and provide technical support for the application of the gardens and virescence.The research on the population structure and the dynamic trend of the future are also studied,in order to investigate their endangered reasons and provide certain scientific basis for its conservation technology research.The seeds of S.pinnatifolia from adult plant were chosen to explore the seed dormancy mechanism through morphologic observation,water-absorption regulation determination and the effect of seed soaking liquid on the germination percentage of Chinese cabbage seed.The effect of different seed soaking temperatures and different concentrations of GA3 on seed germination characteristics was studied by indoor germination experiment.The different temperature and light conditions was simulated to explore the best germination conditions.In this paper,the population survey of S.pinnatifoliainGangou in Helan Mountain and Xiangshan in Zhongwei city was conducted for the first time.Population structure characteristics were described by building static life table and drawing population survival curve.Its future development trend was researched quantificationally using the method of population dynamic prediction and time series analysis.The results wereshowed as follows:(1)S.pinnatifolia seed has good water absorption performance which indicates it has no physical dormancycharacteristic;There were water-soluble germination inhibitors inside the seed,which has chemical dormancy characteristics that can be relieved by controlling the soaking time;The best soaking temperature is 30°C.The soaked seeds had the optimal germination data and the shortest germination starting time at constant temperature of 15°C and 25°C in dark.Light was the most significant factor of influencing seed germinaton.(2)Two populations were lack of seedlings in different degrees.The population development was primarily maintained by middle and older individuals.The population survival curve tended to Deevey-Ⅱ.Survival analysis also showed that Xiangshan population went into decline phase earlier,and affected by the environment moreobviously.Combined with the habitat conditions,Helan Mountaion region was more suitable for the survival of S.pinnatifolia;Two populations of S.pinnatifolia was sensitive to the pressure of environmental conditions and had the dynamic characteristics of early stage declining,middle stage stability and late stage recession.(3)The endangered self-reasons were that the populations were lack of independent update seedlings and seed had chemical dormancycharacter.The external reasons were the natural disasters and human interference.Protection strategieswere put forward: Using seed propagation method to breeda large number of seedlingsto apply in the landscaping;The measures of stumping and artificial planting management were used to protect Gangou population;Xiangshan population can be protected by the way of plant transplanting. |
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