Morphology And Anatomy Of Invasive Biological Characteristics And Sexual Reproduction Control Of An Invasive Plant, Solidago Canadensis

Solidago canadensis L.is a perennial invasive alien plant belonging to Solidago L., Composite.It,originated from North.america,was initially introduced as an ornamental pant to Shanghai in 1935.Then it escaped into the wild and it has been spreading rapidly in China which has become one of the detrimental weeds,especially in east China.Strong invasiveness and harmfulness of Goldernrod.was related with its strong adaptation to different environment and the mode of its reproduction.Especially,its strong infestation was associated closely with the strong sexual reproduction capacity.Hence,to study on adaptive mechanism of the strong invasiveness of Goldernrod and prevent its sexual reproduction are significant to predict the potential invasive region and restrict the diffusion speed.In this paper,we compared the leaf epidermis and stem structures of the populations of Goldernrod in different environment and study the processes of the sexual reproduction of Goldernrod.and its relationship with climatic factors in order to elucidate ecological adaptation mechanism from both phenotypic plasticity and sexual reproduction.In addition, based on a critical period of its sexual reproduction,the use of flower buds NJW001 inhibitors inhibit its flower bud differentiation and stopfruit development in order to explore the new way to prevent its diffusion.The results are as follows.1.Morphologic characters of stems and leaves about 45 populations of Solidago canadensis L.The leaf epidermis and stems structures of 45 populations of Goldernrod in east China have been examined under LM.The results showed that,there were epidermal hairs distributed on the upper epidermis and the lower epidermis.Among all the populations the density of lower epidermal hair was bigger than the density of lower epidermal hair,and there was positive correlation between them.The upper epidermal cells of all the populations are polygonal,the lower epidermal cells were usually irregular or approximately polygonal.The patterns of anticlinal walls of the lower epidermal cells were slightly straight,arched and sinuolate.The stomatal apparatuses of all the populations of Goldernrod were anomocytic type.The differences of density of upper and lower epidermal hair,stomal density,the ratio of vascular bundle number and stems and the medulla proportion in the stem area were significant among the populations.The phenotypic plasticity of stomal density,was the biggest.Furthermore,correlation analysis showed that there was positive correlation between the stomal density and soil humidity.The differences among different populations and the phenotypic plasticity may contribute to the invasiveness of the weed.2.A glimpse of invasiveness of Sotidago canadensis L.through observation of its sexual reproductive biology processCompared with the original populations in Canada,the sexual reproductive process of invaded Goldernrod populations in east China delayed two months,which allowed them to vegetative-grow longer and up higher in height of individual so as to enhance their competitiveness.We have thoroughly studied the process of sexual reproduction of Goldernrod including floral bud differentiation,megasporogenesis,microsporogenesis, development of female and male gametophyte and embryo and comparatively analyzed the relationship between the differential process and climatic factors of both China and Canada. The purposes of this paper are to clarify interpretation of the reason of the delay of its florescence and elucidate the mechanism of its stronger invasiveness.The results showed that there was a close relationship between the length of capitulum and the process of the development.Floral bud differentiated when the length of capitulum was 0-1.73±0.08mm. Meiosis of megaspore mother cells(MMCs) and pollen mother cells(PMCs) occurred at 3.50±0.10-3.50±0.10 mm of the length of capitulum.The mature pollen grains and megaspore produced at 5.15±0.14 mm.Development of the anther wall was dicotyledonous type,and the mature pollen grains 3-celled.The tapetum was amoeboid type.The ovule was single integument,thin nucellus and anatropous.The development of the embryo sac was polygonum type with multiple antipodals,and the antipodals cells arrayed in tandem. The development of embryo belonged to chenopodiad type.Plant morphology of different developmental stages was recorded.Temperature rather than the length of daylight may mainly induce floral bud differentiation process.Obviously,the process from floral bud differentiation to seed formation inherently adapting to temperature and asynchronization of flowering phenology may contribute to its invasiveness.3.Studies on the inhibition of flowerbud inhibitors to reproductive development of Solidago canadensis L.The flowerbud inhibitor NJW001 was sprayed onto Goldernrod plants in final growth stage,initial stage of flower bud differentiation,initial stage of megasporogenesis, microsporogenesis,final stage of megasporogenesis,microsporogenesis and full-bloom stage respectively.The results showed that,at the end of August,when the top leaves become narrow,the axillary buds were branching,but spherical flower bud had not formed, the flower bud inhibitor was applied at 0.10%and could reduce the fruit setting amount and seed germination rate effectively.From early September to mid September,when flower bud differentiation occurred and the top leaves grew like rosette,green spherical flower buds were compactly found in leaf axil,0.06%of the flower bud inhibitor could inhibit the fruit setting and reduce seed germination rate effectively,In mid September,when the microspore and megaspore began to develop the capitulum became olive shape,and the green panicle inflorescence developed,the effective inhibitor concentration was at about 0.10%.At the microspore and megaspore complete development stage at end of September, when the capitulum was cylindrical and longer,and the particle inflorescence became yellowish green,0.16%of the inhibitor was quite effective in this stage.Full-bloom stage was in mid October,when the panicle inflorescence was golden,the capitulum and the corolla of tubular flower were blossoming,only higher than 0.20%of the inhibitor was effective enough to inhibt fruit development.Comprehensively considered the factors of efficacy and cost,the optimum application period for the flowerbud inhibitor was at the initial stage of flower bud differentiation.