Investigation On Reproductive Characteristics Of Leucanthemum Maximum And Tanacetum Parthenium

Chrysanthemum(Chrysanthemum morifolium)in China has a thousand years of cultural history,and it is one of the ten traditional flowers and one of the four cut flowers.Both in cultural and economic fields,chrysanthemum has a pivotal position.Currently crossbreeding breeding methods on chrysanthemum is still the most widely utilized and the maximum efficiency breeding methods,Daisy and related genera of plants tend to have better resistance than cultivated chrysanthemum,these features are cultivated chrysanthemum need.These excellent resistance and tolerance can be transferred to the cultivation of chrysanthemum crossbreeding by modern technology.So that these become chrysanthemum plant germplasm and improved varieties of important parent.But the breeding process often appear low seed,embryo abortion and other issues.How to guide the breeding farm better and raise the percentage of seed?This requires us to be familiar with the reproductive process of the development of wild chrysanthemum and knowing their abortion laws and strong reasons for the low rate,and in order to find a solution.Ultimately improve its rate of hybrid seed of cultivation chrysanthemum plants and provide a strong theoretical foundation for how to better hybrids and cultivated chrysanthemum plants.What's more,through investigation on microsporogenesis,megasporogenesis and embryogenesis in Dendranthema and related plants.It can understand reproductive characteristics of them.and enrich the information of them.And for the subsequent conduct compositae taxonomy to provide relevant information theory.we also study Megasporogenesis,microsporogenesis,development of gametophyte and embryogenesis in Leucanthemum maximum and embryogenesis in Tanacetum parthenium We also use in vitro culture techniques to measure pollen viability on Leucanthemum maximum and Tanacetum parthenium.The results show that:1.Leucanthemum maximum tubular floret contains five anthers,each have two pairs of anthers mature sporangia,each anthers mature sporangia has a big one and a small one.It is typical type for dicotyledonous plant.The anther wall is consisting of(from the outer to the inner side)the epidermis,the endothecium,the middle layer and the tapetum.The middle layer disappears in the middle period of tetrasporophyte,.The tetrahedral is tetrad.Tapetum is glandular type.The tapetum develops the top in a period of meiosis,then slowly disappeared.Degradation is completed in three nuclear pollen period.The meiosis type of small mother microspores is simultaneous.Mature pollen has three cores,two of them are sperms and the rest one is vegetative nucleu.Pollen germination wall has three holes,The vitro germination rate of Leucanthemum maximum was 11.67%.The pistil has an ovary that contains one anatropous ovule,dual-integument,tenuinucellatae,the development of embryo follows the oenothera type.The archesporial cell below nucellus epiderm functions directly as the megaspore mother cell,and the megasporocyte undergoes two successive divisions to form a linear tetrad with four haploid megaspores.2.Tanacetum parthenium embryonic development is basically abortion.Apart from a few is due to the female gamete development stage had stopped Basically stopped in the original embryo developmental stage.It may be related to the change of its environment.The pollen viability is relatively low,only 5.79%.This may also lead to a resoult of embryos abortion.