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Reproductive Biology And Flora Morphogenesis Of Rosa Persica

Posted on:2006-11-08Degree:DoctorType:Dissertation
Country:ChinaCandidate:H Y HeFull Text:PDF
GTID:1100360152992368Subject:Ornamental horticulture
Abstract/Summary:PDF Full Text Request
Rosa persica, a rare species of Rosa.L., was investigated on its flower morphogenesis, reproductive biology and distribution in Xin-jiang, China. The results showed that1. The species, Rosa persica is distrituted in only Xin-jiang in China. The distributing region is between 43°53' 94"~46°43' 15" N in latitude, 83°07' 53"~87°33' 37"E in longitude and 430~748m in altitude. It was found to be endemic to a small area, to occupy a very narrow habitat, to need a strict niche and to appear highly dispersed small populations. Edaphic and community microclimatic factors played a vital role in natural distribution. Rosa persica is a species endemic to Xin-jiang China. Owing to its wild populations are rare, so it is urgent to be protected. The phenophase of Rosa persica was divided into six main stages : sprout stage, vegetative branch stretching stage, blooming stage, fruit development stage, leaf falling stage and resting stage. The appearance characteristic of the each period proceeding was described in details, the biologic characteristics and ecologic adaptability of this kind of special species in the desert and semi-desert was analyzed.2. The flower bud differentiation process lasted for about 30days from bract primordium differentiation in late March to carpel primordium formation in late April. The process could be divided into 6 phases: before differentiation, bract differentiation phase, sepal differentiation phase, petal differentiation phase, stamen differentiation phase and pistil differentiation phase. Of them one time was occurred in differentiation of sepal primordium, and it might be the reason of forming the simple layer of sepal. An larges of each floral primordium originated in peripheral zone cells of floral meristem . The increase of cell number and diameter of apical point was higher in both extension phase and carpel differentiation phase.3. The gynoecium have composed of about 20-free carpels, the ovary is 1-loculed and 1-anatropous ovule. The carpel initiation belongs to the ascidiate type. Styles and stigmas are differentiated as the incipient carpels extend upward, while the inferior ovary is formed by incipient carpels inserting into receptacle, long style and plumate stigma. The degeneration of pistil was observed , and the abortion rate of carpel was about 74.3%. This was considered as a factor responsible for the low seed set in Rosa persica.4. The anther was four-sporangiate, accidentally seen six or seven-sporangiate. The development of anther walls conforms to the basic type, and its wall was composed of four layers: epidermis, fibrous endothelium, middle layer and tapetum respectively, and the tapetum is secretory type. The development of the tapetum with 2-nucleate cells is of the glandular type. Cytokinesis of microspore mother cell in meiosis was successive type and the microspore tetrads were tetrahedral or isobilateral. Tetrad cells and microspores are irregularly shaped during the microsporogensis. The mature pollen grains were 2-celled. During the development process male gametophytes were differently abnormal in stame.5. The gynaecium were polygynous, and the ovule were anatropous, unitegmic and crassinucellate. The megaspore mother cells undergo meiotic divisions and develop into a linear tetradas of megaspores. The chalazal megaspore are functional one, which develops into a polygonum type of embryo sac. The two polar nuclei fused into a secondary nucleus before fertilization. On the blossom day, female gametophyteswere mainly 7-celled with 8-nucleus or 4-celled with antipodal cells degenerated. Three antipodal cells was degenerated. Flowers was protandrous , and porogany . During the development process of female gametophytes were many differently abnormal in embryo sac.6. The embryo development was of the solanaceous type. In two days after pollination zygote begins dividing. And the first division of the zygote took place after the cellularization of endosperm free nuclei. After the club-shaped and the globular embryo period, the heart-shaped embryo develop...
Keywords/Search Tags:Rosa persica, Reproductive biology
PDF Full Text Request
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