| Swida wilsoniana Wanger is a deciduous broad leaf tree with grey-green mottled trunks as the key ornamental features. It can adapt to barren hills, wasteland, and soil erosion area. Most importantly, it is a candidate plant for biodiesel because of 33%-36% high oil content in its fruit. Extensive attentions have been paid to Swida wilsoniana, especially on the collection, identification, and utilization.In this research,7 clones Swida wilsoniana were selected and analyzed on their diversity of agronomic traits by variance, principal component, cluster and correlation analysis methods,and then established parent selection model for hybridization. Meanwhile, pollen morphology and viability, germination characteristics, embryo sac and embryo development characteristics and physio-biochemical changes were observed, by means of paraffin section, florescent microscopy, scanning electron microscope and physio-biochemistry index. The research results would be the basis for Swida wilsoniana parent selection of hybridization and scientific guidance to improve seed setting rate and to rescue hybrid embryo. The main results were as followings:1. Variance analysis showed that the variation coefficients of 28 agronomic characters of the 7 clones ranged from 8.04% to 94.30%, and the biggest variation (45.27%-94.30%) was leafy morphological traits, such as leaf shape, leaf color and leaf margin. Phenotypic differentiation coefficients ranged from 45.27% to 96.40%, and which showed that the inheritances of various characters were relatively stable. The main inheritances were presented by four principal components, which were inflorescence, fruit, oil content and fruit number per cluster.2. According to the factor scores that resulted from principal component analysis, the 7 clones were clustered into 4 groups. The potential hybrid of high-yield with high-oil content would be obtained by crossing group II (Clone 713 was high-yield species with ellipse and flat leaves, more fruit per cluster, big fruits and inflorescences) with group Ⅲ (Clone B03 is high-oil species with lanceolate longer leaves, high oil content but low moisture content, and big clusters but small inflorescences).3. The results showed that Swida wilsoniana pollen was prolate spheroidal and tricolporate with roughened sculpturing. The size of pollen grains among different cultivars were similar, while the sculpturing and furrow spacing varied significantly. The pollen had the highest viability, when 75% of the inflorescence bloomed. The viability of pollen stored at the temperature of 4℃ was much than that stored in -20℃ and -80 ℃, all stored for one month and three months respectively. While at the same temperature, pollen stored for three months had less viability than that stored for 1 month. At 4℃, the viability of pollen from stored whole flower was higher than that from stored stamen. Pollen could regular germinate on stigma, then entered into the ovary after 72 hours of pollination.4. The development of embryo sac of Swida wilsoniana was polygonum-type. Its development process would be divided into six stages:megasporocyte period, metaphase, mononuclear embryo sac period, two-nuclear embryo sac period, four-nuclear embryo sac period and eight-nuclear embryo sac period. The development of embryo would be divided as follow:globular embryo period, heart-shaped embryo period, hill-shaped embryo period, torpedo embryo period, cotyledon embryo period and mature embryo period, hereinto, and early embryonic development could subdivided into spherical proembryo period, spindle embryonic period and triangle embryonic period.30 days after pollination, at globular embryo period, ovary began to enlarge.5. During latest phase of embryo development, high saccharide and starch level was exhibited. The change of protein during the whole period was stable. The level of peroxidase during embryo sac development stage was low, but it rose and maintained a high level during the stage of embryo development. |
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